US20040191536A1 - Electroless process for treating metallic surfaces and products formed thereby - Google Patents

Electroless process for treating metallic surfaces and products formed thereby Download PDF

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US20040191536A1
US20040191536A1 US10/820,692 US82069204A US2004191536A1 US 20040191536 A1 US20040191536 A1 US 20040191536A1 US 82069204 A US82069204 A US 82069204A US 2004191536 A1 US2004191536 A1 US 2004191536A1
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medium
silicate
water
zinc
samples
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Robert Heimann
Brank Popov
Bruce Flint
Dragan Slavkov
Craig Bishop
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    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09DCOATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D1/00Coating compositions, e.g. paints, varnishes or lacquers, based on inorganic substances
    • C09D1/02Coating compositions, e.g. paints, varnishes or lacquers, based on inorganic substances alkali metal silicates
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B28/00Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C04B28/24Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing alkyl, ammonium or metal silicates; containing silica sols
    • C04B28/26Silicates of the alkali metals
    • CCHEMISTRY; METALLURGY
    • C23COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23CCOATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/60Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using alkaline aqueous solutions with pH greater than 8
    • CCHEMISTRY; METALLURGY
    • C23COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23CCOATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/60Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using alkaline aqueous solutions with pH greater than 8
    • C23C22/62Treatment of iron or alloys based thereon
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00474Uses not provided for elsewhere in C04B2111/00
    • C04B2111/00482Coating or impregnation materials
    • C04B2111/00525Coating or impregnation materials for metallic surfaces
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/10Compositions or ingredients thereof characterised by the absence or the very low content of a specific material
    • C04B2111/1006Absence of well-defined organic compounds
    • C04B2111/1012Organic solvents
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/10Compositions or ingredients thereof characterised by the absence or the very low content of a specific material
    • C04B2111/1075Chromium-free or very low chromium-content materials
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/90Electrical properties
    • C04B2111/94Electrically conducting materials
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/12All metal or with adjacent metals
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/12All metal or with adjacent metals
    • Y10T428/12493Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12535Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.] with additional, spatially distinct nonmetal component
    • Y10T428/12611Oxide-containing component
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/12All metal or with adjacent metals
    • Y10T428/12493Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12771Transition metal-base component
    • Y10T428/12785Group IIB metal-base component
    • Y10T428/12792Zn-base component
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/12All metal or with adjacent metals
    • Y10T428/12493Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12771Transition metal-base component
    • Y10T428/12785Group IIB metal-base component
    • Y10T428/12792Zn-base component
    • Y10T428/12799Next to Fe-base component [e.g., galvanized]
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/29Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof

Definitions

  • the instant invention relates to a process for forming a deposit on the surface of a metallic or conductive surface.
  • the process employs a process to deposit, for example, a mineral containing coating or film upon a metallic, metal containing or an electrically conductive surface.
  • Silicates have been used in electrocleaning operations to clean steel, tin, among other surfaces. Electrocleaning is typically employed as a cleaning step prior to an electroplating operation. Usage of silicates as cleaners is described in “Silicates As Cleaners In The Production of Tinplate” is described by L. J. Brown in February 1966 edition of Plating; European Patent No. 00536832/EP B1 (Metallgesellschaft AG); U.S. Pat. Nos. 5,902,415, 5,352,296 and 4,492,616.
  • the instant invention solves problems associated with conventional practices by providing an electroless process for treating metallic surfaces.
  • electroless it is meant that no current is applied from an external source (a current may be generated in-situ due to an interaction between the metallic surface and the medium).
  • the process employs a silicate medium having a controlled and predetermined silicate concentration, temperature and pH.
  • the silicate medium that interacts with the metallic surface to form surface having one or more improved properties.
  • the inventive process controls the medium's characteristics and the surrounding environment in order to obtain a desired film or layer upon the metal surface, e.g, a film or layer having low surface porosity or high density.
  • the characteristics of the film or layer can be controlled or modified by varying the temperature, pH, lattice builders (i.e., medium dopants), rate of formation, heat, pressure, pre and post treatments and silicate concentration.
  • the inventive process can form a surface comprising a mineral layer comprising an amorphous matrix surrounding or incorporating metal silicate crystals upon the substrate.
  • a mineral layer comprising an amorphous matrix surrounding or incorporating metal silicate crystals upon the substrate.
  • a metallic surface that is treated (e.g., forming the mineral layer) by the inventive process can possess improved corrosion resistance, increased electrical resistance, heat resistance, flexibility, resistance to stress crack corrosion, adhesion to topcoats, among other properties.
  • the improved heat resistance broadens the range of processes that can be performed subsequent to forming the inventive layer, e.g., heat cured topcoatings, stamping/shaping, riveting, among other processes.
  • the treated surface also imparts greater corrosion resistance (e.g., ASTM B-117), among other beneficial properties, than conventional tri-valent or hexa-valent chromate systems.
  • the inventive process can provide a zinc-plate article having an ASTM B-117 resistance to white rust of at least about 96 hours (and normally greater than about 150 hours), and resistance to red rust of at least about 250 (and normally greater than about 400 hours).
  • the corrosion resistance can be improved by adding a dopant to the silicate medium, using a rinse and/or applying at least one sealer/topcoating.
  • inventive process is a marked improvement over conventional methods by obviating the need for solvents or solvent containing systems to form a corrosion resistant layer, e.g., a mineral layer.
  • inventive process can be substantially solvent free.
  • substantially solvent free it is meant that less than about 5 wt. %, and normally less than about 1 wt. % volatile organic compounds (V.O.C.s) are present in the electrolytic environment.
  • the inventive process is also a marked improvement over conventional methods by reducing, if not eliminating, chromate and/or phosphate containing compounds (and issues attendant with using these compounds such as waste disposal, worker exposure, among other undesirable environmental impacts). While the inventive process can be employed to enhance chromated or phosphated surfaces, the inventive process can replace these surfaces with a more environmentally desirable surface. The inventive process, therefore, can be “substantially chromate free” and “substantially phosphate free” and in turn produce articles that are also substantially chromate (hexavalent and trivalent) free and substantially phosphate free. The inventive process can also be substantially free of heavy metals such as chromium, lead, cadmium, barium, among others.
  • substantially chromate free, substantially phosphate free and substantially heavy metal free it is meant that less than 5 wt. % and normally about 0 wt. % chromates, phosphates and/or heavy metals are present in a process for producing an article or the resultant article.
  • Non-Provisional patent application Ser. No. 09/016,849 (Attorney Docket No. EL004RH-1), filed on Jan. 30, 1998 and entitled “Corrosion Protective Coatings”.
  • the subject matter of this invention is also related to Non-Provisional patent application Ser. No. 09/016,462 (Attorney Docket No. EL005NM-1), filed on Jan. 30, 1998 and entitled “Aqueous Gel Compositions and Use Thereof” (now U.S. Pat. No. 6,033,495).
  • Non-Provisional patent application Ser. No. 09/814,641 (Attorney Docket No. EL008RH-6), filed on Mar. 22, 2001, and entitled “An Energy Enhanced Process For Treating A Conductive Surface And Products Formed Thereby” (and corresponds to PCT Patent Application Serial No. PCT/US01/09293)
  • Non-Provisional patent application Ser. No. ______ (Attorney Docket No. EL023RH-1), filed on Aug. 03, 2002 and entitled “An Electrolytic And Electroless Process For Treating Metallic Surfaces And Products Formed Thereby”, and Ser. No. ______ (Attorney Docket No. EL022RH-1), filed on Aug. 03, 2002 and entitled “Process For Treating A Conductive Surface And Products Formed Thereby”.
  • FIG. 1 illustrates the open-circuit potential of galvanized steel panels immersed in the inventive medium having a pH 10.5.
  • FIG. 2 illustrates the open-circuit potential of galvanized steel panels immersed in the inventive medium having a pH 11.
  • FIG. 3 illustrates the open-circuit potential of galvanized steel panels immersed in the inventive medium having a pH of 11.5.
  • FIG. 4 illustrates the open-circuit potential of galvanized steel panels immersed in the inventive medium having a pH 12.
  • FIG. 5 illustrates the corrosion potentials of galvanized steel panels immersed in the inventive medium having a temperature of 75 C and pHs of 10.5, 11, 11.5 and 12.
  • FIG. 6 illustrates the corrosion potentials of galvanized steel panesl immersed in the inventive medium having a temperature of 80 C and pHs of 10.5, 11, 11.5 and 12.
  • FIG. 7 illustrates the open circuit potential for galvanized steel panels exposed to pHs of 10.5, 11 and 12.
  • FIG. 8 illustrates a comparison of the SEM and EDAX analysis of samples exposed to the inventive medium and rinsed immediately and rinsed after 24 hours.
  • FIG. 9 illustrates a comparison of increasing amounts of sodium borohydride addition to the inventive medium.
  • FIG. 10 illustrates a comparison of corrosion resistance of samples treated with the inventive medium with sodium borohydride addition.
  • FIG. 11 illustrates a comparison of corrosion resistance of samples treated with the inventive medium with sodium borohydride addition and a thermal post-treatment.
  • FIG. 12 illustrates a voltagrams for samples treated in the inventive medium with sodium borohydride addition.
  • FIG. 13 illustrates inhibiting efficiencies based upon the voltagrams of FIG. 12.
  • FIG. 14 illustrates a voltagrams for samples treated in the inventive medium with sodium borohydride addition and a thermal post-treatment.
  • FIG. 15 illustrates inhibiting efficiencies based upon the voltagrams of FIG. 14.
  • FIG. 16 illustrates cyclic voltagrams for samples treated in the inventive medium with sodium borohydride addition.
  • FIG. 17 illustrates inhibiting efficiencies based upon the voltagrams of FIG. 16.
  • FIG. 18 illustrates the affect on inhibiting efficiencies on air dried samples after immersion in water for one week.
  • FIG. 19 illustrates the affect on inhibiting efficiencies on samples having a thermal post-treatment after immersion in water for one week.
  • FIG. 20 illustrates an SEM image of samples treated with the inventive medium with sodium borohydride addition before and after immersion in water.
  • FIG. 21 illustrates an EDAX of samples treated with the inventive medium with sodium borohydride addition.
  • FIG. 22 illustrates an EDAX of samples treated with the inventive medium with sodium borohydride addition and a thermal post treatment.
  • the instant invention relates to a process for depositing or forming a beneficial surface (e.g., a mineral containing coating or film) upon a metallic surface.
  • a beneficial surface e.g., a mineral containing coating or film
  • the process contacts at least a portion of a metal surface with a silicate medium, e.g., containing soluble mineral components or precursors thereof, having controlled and predetermined silicate concentration, temperature and pH.
  • silicate medium e.g., containing soluble mineral components or precursors thereof, having controlled and predetermined silicate concentration, temperature and pH.
  • silicate medium e.g., containing soluble mineral components or precursors thereof, having controlled and predetermined silicate concentration, temperature and pH.
  • mineral containing coating “mineralized film” or “mineral” it is meant to refer to a relatively thin coating or film which is formed upon a metal surface wherein at least a portion of the coating or film comprises at least one metal containing mineral, e.g., an amorphous phase or
  • metal containing By “metal containing”, “metal”, or “metallic”, it is meant to refer to sheets, shaped articles, fibers, rods, particles, continuous lengths such as coil and wire, metallized surfaces, among other configurations that are based upon at least one metal and alloys including a metal having a naturally occurring, or chemically, mechanically or thermally modified surface.
  • a naturally occurring surface upon a metal will comprise a thin film or layer comprising at least one oxide, hydroxides, carbonates, sulfates, chlorides, among others. The naturally occurring surface can be removed or modified by using the inventive process.
  • the metal surface refers to a metal article or body as well as a non-metallic member having an adhered metal or conductive layer. While any suitable surface can be treated by the inventive process, examples of suitable metal surfaces comprise at least one member selected from the group consisting of galvanized surfaces, sheradized surfaces, zinc, iron, steel, brass, copper, nickel, tin, aluminum, lead, cadmium, magnesium, alloys thereof such as zinc-nickel alloys, tin-zinc alloys, zinc-cobalt alloys, zinc-iron alloys, among others.
  • the mineral layer can be formed on a non-conductive substrate having at least one surface coated with a metal, e.g., a metallized polymeric article or sheet, ceramic materials coated or encapsulated within a metal, among others.
  • a metal e.g., a metallized polymeric article or sheet, ceramic materials coated or encapsulated within a metal, among others.
  • metallized polymer comprise at least one member selected from the group of polycarbonate, acrylonitrile butadiene styrene (ABS), rubber, silicone, phenolic, nylon, PVC, polyimide, melamine, polyethylene, polyproplyene, acrylic, fluorocarbon, polysulfone, polyphenyene, polyacetate, polystyrene, epoxy, among others.
  • Conductive surfaces can also include carbon or graphite as well as conductive polymers (polyaniline for example).
  • the metal surface can possess a wide range of sizes and configurations, e.g., fibers, coils, sheets including perforated acoustic panels, chopped wires, drawn wires or wire strand/rope, rods, couplers (e.g., hydraulic hose couplings), fibers, particles, fasteners (including industrial and residential hardware), brackets, nuts, bolts, rivets, washers, cooling fins, stamped articles, powdered metal articles, among others.
  • the limiting characteristic of the inventive process to treat a metal surface is dependent upon the ability of the surface to be contacted with the inventive silicate medium.
  • the inventive process can be operated on a batch or continuous basis.
  • the type of process will depend upon the configuration of the metal being treated.
  • the contact time within the silicate medium ranges from about 10 seconds to about 50 minutes and normally about 1 to about 15 minutes.
  • the inventive process can be practiced in any suitable apparatus. Examples of suitable apparatus comprise a batch process performed in polyproplyene tanks having means for circulating the silicate medium and maintaining a predetermined temperature.
  • the silicate containing medium can be a fluid bath, gel, spray, fluidized beds, among other methods for contacting the substrate with the silicate medium.
  • the silicate medium comprise a bath containing at least one silicate, a gel comprising at least one silicate and a thickener, among others.
  • the medium can comprise a bath comprising at least one of potassium silicate, calcium silicate, lithium silicate, sodium silicate, ammonium silicate, compounds releasing silicate moieties or species, among other silicates.
  • the bath can comprise any suitable polar or non-polar carrier such as water, alcohol, ethers, carboxillic acids, among others.
  • the bath comprises at least one water-soluble silicate such as sodium silicate and de-ionized water and optionally at least one dopant (e.g. chlorides among other monovalent species).
  • the at least one dopant is water soluble or dispersible within an aqueous medium.
  • the silicate containing medium typically has a basic pH. Normally, the pH will range from greater than about 9 to about 13 and typically, about 10 to about 12.
  • the pH of the medium can be monitored and maintained by using conventional detection and delivery methods. The selected detection method should be reliable at relatively high sodium concentrations and under ambient conditions.
  • the silicate medium is normally aqueous and can comprise at least one water soluble or dispersible silicate in an amount from greater than about 0 to about 40 wt. %, usually, about 1 to 15 wt. % and typically about 3 to 8 wt. %.
  • the amount of silicate in the medium should be adjusted to accommodate silicate sources having differing concentrations of silicate.
  • the silicate containing medium is also normally substantially free of heavy metals, chromates and/or phosphates.
  • the silicate medium can be modified by adding at least one stabilizing compound (e.g., stabilizing by complexing metals).
  • a suitable stabilizing compound comprises phosphines, sodium citrate, ammonium citrate, ammonium iron citrate, sodium salts of ethylene diamine tetraacetic acid (EDTA) and nitrilotriacetic acid (NTA), 8-hydroxylquinoline, 1,2-diaminocyclohexane-tetracetyic acid, diethylene-triamine pentacetic acid, ethylenediamine tetraacetic acid, ethylene glycol bisaminoethyl ether tetraacetic acid, ethyl ether diaminetetraacetic acid, N′-hydroxyethylethylenediamine triacetic acid, 1-methyl ethylene diamine tetraacetic acid, nitriloacetic acid, pentaethylene hexamine, tetraethylene pentamine, triethylene
  • the silicate medium has a basic pH and comprises at least one water soluble silicate, water and colloidal silica.
  • the silicate medium can also be modified by adding colloidal particles such as colloidal silica (commercially available as Ludox® AM-30, HS-40, among others).
  • the colloidal silica has a particle size ranging from about 10 nm to about 50 nm.
  • the size of particles in the medium ranges from about 10 nm to 1 micron and typically about 0.05 to about 0.2 micron.
  • the medium has a turbidity of about 10 to about 700, typically about 50 to about 300 Nephelometric Turbidity Units (NTU) (as determined in accordance with conventional procedures).
  • NTU Nephelometric Turbidity Units
  • the temperature of the silicate medium can be controlled to optimize the interaction between the medium and a metal surface. Normally, the temperature will range from about 50 to at least about 100 C and typically about 50 to 100 C (e.g., 55 C). This temperature can be maintained by using conventional heaters and related control systems. If desired, the metal surface can be heated prior to being introduced into the medium.
  • the chemical and/or physical properties of the silicate medium can be affected by exposing the medium to a source of electrical or magnetic energy.
  • the bath can be exposed to a source of energy such as the electrical current described in aforementioned U.S. Ser. No. 09/814,641; hereby incorporated by reference.
  • a source of energy such as the electrical current described in aforementioned U.S. Ser. No. 09/814,641; hereby incorporated by reference.
  • Such exposure can improve the interaction between the medium and the metal surface, partially polymerize the silicate medium, partially crystallize the silicate medium, among other affects.
  • the silicate medium can be modified by adding water/polar carrier dispersible or soluble polymers. If utilized, the amount of polymer or water dispersible materials normally ranges from about 0 wt. % to about 10 wt. %.
  • Examples of polymers or water dispersible materials that can be employed in the silicate medium comprise at least one member selected from the group of acrylic copolymers (supplied commercially as Carbopol®), zirconyl ammonium carbonate, hydroxyethyl cellulose, clays such as bentonite, fumed silica, solutions comprising sodium silicate (supplied commercially by MacDermid as JS2030S), among others.
  • a suitable composition can be obtained in an aqueous composition comprising about 3 wt % silicate (obtained from N-grade Sodium Silicate Solution (PQ Corp) that comprises 25% silicate), optionally about 0.5 wt % Carbopol EZ-2 (BF Goodrich), about 5 to about 10 wt. % fumed silica, mixtures thereof, among others.
  • silicate obtained from N-grade Sodium Silicate Solution (PQ Corp) that comprises 25% silicate
  • PQ Corp N-grade Sodium Silicate Solution
  • Carbopol EZ-2 BF Goodrich
  • fumed silica mixtures thereof, among others.
  • the silicate medium is modified to include at least one dopant material.
  • the dopants can be useful for building additional thickness of the deposited layer, hydroxides of iron, aluminum, manganise, and magnesium among others.
  • the amount of dopant can vary depending upon the properties of the dopant and desired results. Typically, the amount of dopant will range from about 0.001 wt. % to about 5 wt. % of the medium (or greater so long as the deposition rate is not adversely affected).
  • Suitable dopants comprise at least one member selected from the group of water dispersible or soluble salts, oxides and precursors of tungsten, molybdenum (e.g., molybdenum chloride), titanium (titatantes), zircon, vanadium, phosphorus, aluminum (e.g., aluminates, aluminum chloride, etc), iron (e.g., iron chloride), boron (borates), bismuth, cobalt (e.g., cobalt chloride, cobalt oxide, etc.), gallium, tellurium, germanium, antimony, niobium (also known as columbium), magnesium and manganese, nickel (e.g., nickel chloride, nickel oxide, etc.), sulfur, zirconium (zirconates) mixtures thereof, among others, and usually, salts and oxides of aluminum and iron, and hydroxides of iron, aluminum, manganese and magnesium, among others; and other water soluble or dispersible monovalent species.
  • the dopant can comprise at least one of molybdenic acid, fluorotitanic acid and salts thereof such as titanium hydrofluoride, ammonium fluorotitanate, ammonium fluorosilicate and sodium fluorotitanate; fluorozirconic acid and salts thereof such as H 2 ZrF 6 , (NH 4 ) 2 ZrF 6 and Na 2 ZrF 6 ; among others.
  • molybdenic acid such as titanium hydrofluoride, ammonium fluorotitanate, ammonium fluorosilicate and sodium fluorotitanate
  • fluorozirconic acid and salts thereof such as H 2 ZrF 6 , (NH 4 ) 2 ZrF 6 and Na 2 ZrF 6 ; among others.
  • dopants can comprise at least one substantially water insoluble material such as electropheritic transportable polymers, PTFE, boron nitride, silicon carbide, silicon nitride, aluminum nitride, titanium carbide, diamond, titanium diboride, tungsten carbide, silica (e.g., colloidal silica available commercially as Ludox® AM and HS) metal oxides such as cerium oxide, powdered metals and metallic precursors such as zinc, among others.
  • electropheritic transportable polymers PTFE, boron nitride, silicon carbide, silicon nitride, aluminum nitride, titanium carbide, diamond, titanium diboride, tungsten carbide, silica (e.g., colloidal silica available commercially as Ludox® AM and HS) metal oxides such as cerium oxide, powdered metals and metallic precursors such as zinc, among others.
  • PTFE electropheritic transportable polymers
  • the dopant can be dissolved or dispersed without another medium prior to introduction into the silicate medium.
  • at least one dopant can be combined with a basic compound, e.g., sodium hydroxide, and then added to the silicate medium.
  • a basic compound e.g., sodium hydroxide
  • dopants that can be combined with another medium comprise zirconia, cobalt oxide, nickel oxide, molybdenum oxide, titanium (IV) oxide, niobium (V) oxide, magnesia, zirconium silicate, alumina, antimony oxide, zinc oxide, zinc powder, aluminum powder, among others.
  • the aforementioned dopants that can be employed for enhancing mineral layer formation rate, modifying the chemistry and/or physical properties of the resultant layer, as a diluent for the silicate containing medium, among others.
  • dopants are iron salts (ferrous chloride, sulfate, nitrate), aluminum fluoride, fluorosilicates (e.g., K2SiF6), fluoroaluminates (e.g., potassium fluoroaluminate such as K2AlF5-H2O), mixtures thereof, among other sources of metals and halogens.
  • the dopant materials can be introduced to the metal surface in pretreatment steps, in post treatment steps (e.g., rinse), and/or by alternating exposing the metal surface to solutions of dopants and solutions of silicates if the silicates will not form a stable solution with the dopants, e.g., one or more water soluble dopants.
  • the presence of dopants in the silicate medium can be employed to form tailored surfaces upon the metal, e.g., an aqueous sodium silicate solution containing aluminate can be employed to form a layer comprising oxides of silicon and aluminum. That is, at least one dopant (e.g., zinc) can be co-deposited along with at least one siliceous species (e.g., a mineral) upon the substrate.
  • the silicate medium can also be modified by adding at least one diluent.
  • suitable diluent comprise at least one member selected from the group of sodium sulphate, surfactants, de-foamers, colorants/dyes, conductivity modifiers, among others.
  • the diluent e.g., sodium sulfate
  • the amount normally comprises less than about 5 wt. % of the medium, e.g., about 1 to about 2 wt. %.
  • the silicate medium further comprises at least one reducing agent.
  • a suitable reducing agent comprises sodium borohydride, phosphorus compounds such as hypophosphide compounds, phosphate compounds, among others.
  • the reducing agent may reduce water present in the silicate medium thereby modifying the surface pH of articles that contact the silicate medium (e.g., article may induce or catalyze activity of the reducing agent).
  • the concentration of sodium borohydride is typically 1 gram per liter of bath solution to about 20 grams per liter of bath solution more typically 5 grams per liter of bath solution to about 15 gram per liter of bath solution. In one illustrative and preferred embodiment, 10 grams of sodium borohydride per liter of bath solution is utilized.
  • the reducing agent can cause hydrogen evolution once the bath/medium has been sufficiently heated.
  • contact with the inventive silicate medium can be preceded by and/or followed with conventional pre-treatments and/or post-treatments known in this art such as cleaning or rinsing, e.g., immersion/spray within the treatment, sonic cleaning, double counter-current cascading flow; alkali or acid treatments, among other treatments.
  • cleaning or rinsing e.g., immersion/spray within the treatment, sonic cleaning, double counter-current cascading flow
  • alkali or acid treatments among other treatments.
  • the post-treated surface can be sealed, rinsed and/or topcoated, e.g., silane, epoxy, latex, fluoropolymer, acrylic, titanates, zirconates, carbonates, urethanes, among other coatings.
  • topcoated e.g., silane, epoxy, latex, fluoropolymer, acrylic, titanates, zirconates, carbonates, urethanes, among other coatings.
  • a pre-treatment comprises exposing the substrate to be treated to at least one of an acid, base (e.g., zincate solution), oxidizer, among other compounds.
  • the pre-treatment can be employed for cleaning oils, removing excess oxides or scale, equipotentialize the surface for subsequent mineralization treatments, convert the surface into a mineral precursor, functionalize the surface (e.g., a hydroxilized surface), among other benefits.
  • Conventional methods for acid cleaning metal surfaces are described in ASM, Vol. 5, Surface Engineering (1994), and U.S. Pat. No. 6,096,650; hereby incorporated by reference.
  • the metal surface is pre-treated or cleaned electrolytically by being exposed to an anodic environment. That is, the metal surface is exposed to the silicate medium wherein the metal surface is the anode and a current is introduced into the medium.
  • the process can generate oxygen gas.
  • the oxygen gas agitates the surface of the workpiece while oxidizing the substrate's surface.
  • the surface can also be agitated mechanically by using conventional vibrating equipment. If desired, the amount of oxygen or other gas present during formation of the mineral layer can be increased by physically introducing such gas, e.g., bubbling, pumping, among other means for adding gases.
  • the inventive method can include a thermal post-treatment.
  • the metal surface can be removed from the silicate medium, dried (e.g., at about 100 to 150 C for about 2.5 to 10 minutes), rinsed in deionized water and then dried in order to remove rinse water. This is in contrast to conventional metal treatments that rinse(s) and then dry.
  • the dried surface may be processed further as desired; e.g. contacted with a sealer, rinse or topcoat.
  • the rinse can comprise a reactive component such as a silane, carbonate, zirconate, colloidal silica, among other compounds that interact with the treated metallic surface.
  • the thermal post treatment comprises heating the surface.
  • the amount of heating is sufficient to consolidate or densify the inventive surface without adversely affecting the physical properties of the underlying metal substrate. Heating can occur under atmospheric conditions, within a nitrogen containing environment, among other gases. Alternatively, heating can occur in a vacuum.
  • the surface may be heated to any temperature within the stability limits of the surface coating and the surface material. Typically, surfaces are heated from about 75° C. to about 250° C., more typically from about 150° C. to about 200° C.
  • the heat treated component can be rinsed in water to remove any residual water soluble species and then dried again (e.g., at a temperature and time sufficient to remove water).
  • the inventive surface prior to heating can be contacted with a solution containing a material that reacts with the surface at elevated temperatures, e.g., a eutectic formed between silica and at least one of Al2O3, B2O3, Fe2O3, MgO, phosphates, among others.
  • a material that reacts with the surface at elevated temperatures, e.g., a eutectic formed between silica and at least one of Al2O3, B2O3, Fe2O3, MgO, phosphates, among others.
  • the heating will be sufficient to cause sintering or a desirable interaction without adversely affecting the underlying metal.
  • the metal surface can be exposed to an atmosphere having controlled pressure in order to tailor the treated surface.
  • a post treatment comprises exposing the substrate to a source of at least one carbonate or precursors thereof.
  • carbonate comprise at least one member from the group of gaseous carbon dioxide, lithium carbonate, lithium bicarbonate, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, rubidium carbonate, rubidium bicarbonate, rubidium acid carbonate, cesium carbonate, ammonium carbonate, ammonium bicarbonate, ammonium carbamate and ammonium zirconyl carbonate.
  • the carbonate source will be water soluble.
  • the precursor can be passed through a liquid (including the silicate containing medium) and the substrate immersed in the liquid.
  • a suitable postreatment is disclosed in U.S. Pat. No. 2,462,763; hereby incorporated by reference.
  • Another specific example of a post treatment comprises exposing a treated surface to a solution obtained by diluting ammonium zirconyl carbonate (1:4) in distilled water (e.g., Bacote® 20 supplied by Magnesium Elektron Corp). If desired, this post treated surface can be topcoated (e.g., aqueous or water borne topcoats).
  • the post treatment comprises exposing the substrate to a source comprising at least one acid source or precursors thereof.
  • suitable acid sources comprise at least one member chosen from the group of phosphoric acid, hydrochloric acid, molybdic acid, silicic acid, acetic acid, citric acid, nitric acid, hydroxyl substituted carboxylic acid, glycolic acid, lactic acid, malic acid, tartaric acid, ammonium hydrogen citrate, ammonium bifluoride, fluoboric acid, fluorosilicic acid, among other acid sources effective at improving at least one property of the treated metal surface.
  • the pH of the acid post treatment may be modified by employing at least one member selected from the group consisting of ammonium citrate dibasic (available commercially as Citrosol® #503 and Multiprep®), fluoride salts such as ammonium bifluoride, fluoboric acid, fluorosilicic acid, among others.
  • the acid post treatment can serve to activate the surface thereby improving the effectiveness of rinses, sealers and/or topcoatings (e.g., surface activation prior to contacting with a sealer can improve cohesion between the surface and the sealer thereby improving the corrosion resistance of the treated substrate).
  • the acid source will be water soluble and employed in amounts of up to about 15 wt. % and typically, about 1 to about 5 wt. % and have a pH of less than about 5.5.
  • the post treatment comprises contacting a surface treated by the inventive process with a rinse.
  • a rinse it is meant that an article or a treated surface is sprayed, dipped, immersed or other wise exposed to the rinse in order to affect the properties of the treated surface.
  • a surface treated by the inventive process is immersed in a bath comprising at least one rinse.
  • the rinse can interact or react with at least a portion of the treated surface. Further the rinsed surfaced can be modified by multiple rinses, heating, topcoating, adding dyes, lubricants and waxes, among other processes.
  • suitable compounds for use in rinses comprise at least one member selected from the group of titanates, titanium chloride, tin chloride, zirconates, zirconium acetate, zirconium oxychloride, fluorides such as calcium fluoride, tin fluoride, titanium fluoride, zirconium fluoride; coppurous compounds, ammonium fluorosilicate, metal treated silicas (e.g., Ludox®), combinations comprising colloidal silica, nitrates such as aluminum nitrate; sulphates such as magnesium sulphate, sodium sulphate, zinc sulphate, silanes, siloxyanes, siloxyenes, and copper sulphate; lithium compounds such as lithium acetate, lithium bicarbonate, lithium citrate, lithium metaborate, lithium vanadate, lithium tungstate, among others.
  • fluorides such as calcium fluoride, tin fluoride, titanium fluoride, zirconium fluoride
  • the rinse can further comprise at least one organic compound such as vinyl acrylics, fluorosurfactancts, polyethylene wax, TEOS, zirconyl ammonium carbonate, among others.
  • organic compound such as vinyl acrylics, fluorosurfactancts, polyethylene wax, TEOS, zirconyl ammonium carbonate, among others.
  • Examples of commercially available rinses, sealers and topcoats comprise at least one member selected from the group of Aqualac® (urethane containing aqueous solution), W86®, W87®, B37®, T01®, E10®, B17, B18 among others (a heat cured coating supplied by the Magni® Group), JS2030S (sodium silicate containing rinse supplied by MacDermid Incorporated), JS20401 (a molybdenum containing rinse also supplied by MacDermid Incorporated), EnSeal® C-23 (an acrylic based coating supplied by Enthone), EnSeal® C-26, Enthone®
  • One specific rinse comprises water, water dispersible urethane, and at least one silicate, e.g., refer to commonly assigned U.S. Pat. No. 5,871,668; hereby incorporated by reference. While the rinse can be employed neat, normally the rinse will be dissolved, diluted or dispersed within another medium such as water, organic solvents, among others. While the amount of rinse employed depends upon the desired results, normally the rinse comprises about 0.1 wt % to about 50 wt. % of the rinse medium.
  • the rinse can be employed as multiple applications and, if desired, heated.
  • the rinse can be employed after a thermal treatment, e.g., after removing from the silicate medium the part is dried and then rinsed.
  • the aforementioned rinses can be modified by incorporating at least one dopant, e.g. the aforementioned dopants.
  • the dopant can employed for interacting or reacting with the treated surface.
  • the dopant can be dispersed in a suitable medium such as water and employed as a rinse.
  • the inventive process can create a flexible surface that can survive secondary processes, e.g., metal deformation for riveting, sweging, crimping, among other processes, and continue to provide corrosion protection. Such is in contrast to typical corrosion inhibitors such as chromates that tend to crack when the underlying surface is shaped.
  • the surface formed by the inventive process can be topcoated (e.g, with a heat cured epoxy), prior to secondary processing. Articles treated in accordance with the inventive process, topcoated and exposed to a secondary process retain their desirable corrosion resistance, coating adhesion, component functionality, among properties.
  • the inventive process can provide a surface (e.g., mineral coating) that can enhance the surface characteristics of the metal or conductive surface such as resistance to corrosion, protect carbon (fibers for example) from oxidation, stress crack corrosion (e.g., stainless steel), hardness, thermal resistance, improve bonding strength in composite materials, provide dielectric layers, improve corrosion resistance of printed circuit/wiring boards and decorative metal finishes, and reduce the conductivity of conductive polymer surfaces including application in sandwich type materials.
  • a surface e.g., mineral coating
  • the mineral coating can also affect the electrical and magnetic properties of the surface. That is, the mineral coating can impart electrical resistance or insulative properties to the treated surface.
  • articles having the inventive layer can reduce, if not eliminate, electro-galvanic corrosion in fixtures wherein current flow is associated with corrosion, e.g., bridges, pipelines, among other articles.
  • the workpiece can be coated with a secondary coating or layer.
  • the treated workpiece can be rinsed (as described above) and then coated with a secondary coating or layer.
  • secondary coatings or layers comprise one or more members of acrylic coatings (e.g., IRILAC®), e-coats, silanes including those having amine, acrylic and aliphatic epoxy functional groups, latex, urethane, epoxies, silicones, alkyds, phenoxy resins (powdered and liquid forms), radiation curable coatings (e.g., UV curable coatings), lacquer, shellac, linseed oil, among others.
  • acrylic coatings e.g., IRILAC®
  • e-coats silanes including those having amine, acrylic and aliphatic epoxy functional groups, latex, urethane, epoxies, silicones, alkyds, phenoxy resins (powdered and liquid forms
  • radiation curable coatings e.
  • Secondary coatings can be solvent or water borne systems. Secondary coatings can also include corrosion inhibitors, torque tension modifiers, among other additives (e.g., a coating comprising urethanes, acrylics, corrosion inhibitor and sodium silicate).
  • the secondary coatings can be applied by using any suitable conventional method such as immersing, dip-spin, spraying, among other methods.
  • the secondary coatings can be cured by any suitable method such as UV exposure, heating, allowed to dry under ambient conditions, among other methods.
  • An example of UV curable coating is described in U.S. Pat. Nos. 6,174,932 and 6,057,382; hereby incorporated by reference.
  • the surface formed by the inventive process will be rinsed, e.g., with at least one of deionized water, silane or a carbonate, or subjected to a thermal treatment (e.g., removal from the silicate bath, dried and then rinsed to remove residual material), prior to applying a topcoat.
  • the secondary coatings can be employed for imparting a wide range of properties such as improved corrosion resistance to the underlying mineral layer, reduce torque tension, a temporary coating for shipping the treated workpiece, decorative finish, static dissipation, electronic shielding, hydrogen and/or atomic oxygen barrier, among other utilities.
  • the mineral coated metal, with or without the secondary coating can be used as a finished product or a component to fabricate another article.
  • the thickness of the rinse, sealer and/or topcoat can range from about 0.00001 inch to about 0.025 inch.
  • the selected thickness varies depending upon the end use of the coated article. In the case of articles having close dimensional tolerances, e.g., threaded fasteners, normally the thickness is less than about 0.00005 inch.
  • silica containing layer can be formed.
  • silica it is meant a framework of interconnecting molecular silica such as SiO4 tetrahedra (e.g., amorphous silica, cristabalite, triydmite, quartz, among other morphologies depending upon the degree of crystalinity), monomeric or polymeric species of silicon and oxide, monomeric or species of silicon and oxide embedding colloidal species, among others.
  • the crystalinity of the silica can be modified and controlled depending upon the conditions under which the silica is deposited, e.g., temperature and pressure.
  • the silica containing layer may comprise: 1) low porosity silica (e.g., about 60 angstroms to 0.5 microns in thickness), 2) collodial silica (e.g., about 50 angstroms to 0.5 microns in thickness), 3) a mixture comprising 1 and 2, 4) residual silicate such as sodium silicate and in some cases combined with 1 and 2; and 5) monomeric or polymeric species optionally embedding other colloidal silica species such as colloidal silica.
  • the formation of a silica containing layer can be enhanced by the addition of colloidal particles to the silicate medium.
  • colloidal particles comprise colloidal silica having a size of at least about 12 nanometers to about 0.1 micron (e.g., Ludox® HS 40, AM 30, and CL).
  • the colloidal silica can be stabilized by the presence of metals such as sodium, aluminum/alumina, among others.
  • the silica containing film or layer can be provided in as a secondary process. That is, a first film or layer comprising a disilicate can be formed upon the metallic surface and then a silica containing film or layer is formed upon the disilicate surface.
  • a first film or layer comprising a disilicate can be formed upon the metallic surface and then a silica containing film or layer is formed upon the disilicate surface.
  • An example of this process is described in U.S. Patent Application Serial No. 60/354,565, filed on Feb. 05, 2002 and entitled “Method for Treating Metallic Surfaces”; the disclosure of which is hereby incorporated by reference.
  • the silica containing layer can be chemically or physically modified and employed as an intermediate or tie-layer.
  • the tie-layer can be used to enhance bonding to paints, coatings, metals, glass, among other materials contacting the tie-layer. This can be accomplished by binding to the top silica containing layer one or more materials which contain alkyl, fluorine, vinyl, epoxy including two-part epoxy and powder paint systems, silane, hydroxy, amino, mixtures thereof, among other functionalities reactive to silica or silicon hydroxide.
  • the silica containing layer can be removed by using conventional cleaning methods, e.g, rinsing with de-ionized water, or one of the aforementioned post-treatments, e.g. acid rinsing.
  • the silica containing layer can be chemically and/or physically modified by employing the previously described post-treatments, e.g., exposure to at least one carbonate or acid source.
  • the post-treated surface can then be contacted with at least one of the aforementioned secondary coatings, e.g, a heat cured epoxy.
  • the mineral without or without the aforementioned silica may layer functions as an intermediate or tie-layer for one or more secondary coatings, e.g., silane containing secondary coatings.
  • secondary coatings e.g., silane containing secondary coatings.
  • Examples of such secondary coatings and methods that can be complimentary to the instant invention are described in U.S. Pat. Nos. 5,759,629; 5,750,197; 5,539,031; 5,498,481; 5,478,655; 5,455,080; and 5,433,976. The disclosure of each of these U.S. Patents is hereby incorporated by reference.
  • improved corrosion resistance of a metal substrate can be achieved by using a secondary coating comprising at least one suitable silane in combination with a mineralized surface.
  • Suitable silanes comprise at least one members selected from the group consisting of tetraethylorthosilicate (TEOS) and TMOS with styrene, and etc., bis-1,2-(triethoxysilyl) ethane (BSTE), vinyl silane or aminopropyl silane, epoxy silanes, alkoxysilanes, methacryloxypropyl trimethoxysilanes, glycidoxypropyl trimethoxysilane, vinyltriactoxysilane, among other organo functional silanes.
  • the silane can bond with the mineralized surface and then the silane can cure thereby providing a protective top coat, or a surface for receiving an outer coating or layer.
  • a steel substrate e.g., a fastener
  • a steel substrate can be treated by the inventive process to form a mineral layer, allowed to dry, rinsed in deionized water, coated with a 5% BSTE solution, coated again with a 5% vinyl silane solution, and powder coated with a thermoset epoxy paint (Corvel 10-1002 by Morton) at a thickness of 2 mils.
  • a thermoset epoxy paint Corvel 10-1002 by Morton
  • the inventive process forms a surface that has improved adhesion to outer coatings or layers, e.g., secondary coatings.
  • suitable outer coatings comprise at least one member selected from the group consisting of acrylics, epoxies, e-coats, latex, urethanes, silanes (e.g., TEOS, TMEOS, among others), fluoropolymers, alkyds, silicones, polyesters, oils, gels, grease, among others.
  • An example of a suitable epoxy comprises a coating supplied by The Magni® Group as B17 or B18 top coats, e.g, a galvanized article that has been treated in accordance with the inventive method and contacted with at least one silane and/or ammonium zirconium carbonate and top coated with a heat cured epoxy (Magni® B18) thereby providing a chromate free corrosion resistant article.
  • a corrosion resistant article can be obtained without chromating or phosphating.
  • Such a selection can also reduce usage of zinc to galvanize iron containing surfaces, e.g., a steel surface is mineralized, coated with a silane containing coating and with an outer coating comprising an epoxy.
  • the inventive process forms a surface that can release or provide water or related moieties. These moieties can participate in a hydrolysis or condensation reaction that can occur when an overlying rinse, seal or topcoating cures. Such participation improves the cohesive bond strength between the surface and overlying cured coating.
  • the surface formed by the inventive process can also be employed as an intermediate or tie-layer for glass coatings, glass to metal seals, hermetic sealing, among other applications wherein it is desirable to have a joint or bond between a metallic substrate and a glass layer or article.
  • the inventive surface can serve to receive molten glass (e.g., borosilicate, aluminosilicate, phosphate, among other glasses), while protecting the underlying metallic substrate and forming a seal.
  • the surface formed by the inventive process can also be employed as a heat resistant surface.
  • the surface can be employed to protect an underlying surface from exposure to molten metal (e.g., molten aluminum).
  • the inventive process can provide a surface that improves adhesion between a treated substrate and an adhesive.
  • adhesives comprise at least one member selected from the group consisting of hot melts such as at least one member selected from the group of polyamides, polyimides, butyls, acrylic modified compounds, maleic anhydride modified ethyl vinyl acetates, maleic anhydride modified polyethylenes, hydroxyl terminated ethyl vinyl acetates, carboxyl terminated ethyl vinyl acetates, acid terpolymer ethyl vinyl acetates, ethylene acrylates, single phase systems such as dicyanimide cure epoxies, polyamide cure systems, lewis acid cure systems, polysulfides, moisture cure urethanes, two phase systems such as epoxies, activated acrylates polysulfides, polyurethanes, among others.
  • Two metal substrates having surfaces treated in accordance with the inventive process can be joined together by using an adhesive.
  • one substrate having the inventive surface can be adhered to another material, e.g., joining treated metals to plastics, ceramics, glass, among other surfaces.
  • the substrate comprises an automotive hem joint wherein the adhesive is located within the hem.
  • the improved cohesive and adhesive characteristics between a surface formed by the inventive process and polymeric materials can permit forming acoustical and mechanical dampeners, e.g., constraint layer dampers such as described in U.S. Pat. No. 5,678,826 hereby incorporated by reference, motor mounts, bridge/building bearings, HVAC silencers, highway/airport sound barriers, among other articles.
  • the ability to improve the bond between vistoelastomeric materials sandwiched between metal panels in dampers reduces sound transmission, improves formability of such panels, reduces process variability, among other improvements.
  • the metal panels can comprise any suitable metal such as 304 steel, stainless steel, aluminum, cold rolled steel, zinc alloys, hot dipped zinc or electrogalvanized, among other materials.
  • Examples of polymers that can be bonded to the inventive surface and in turn to an underlying metal substrate comprise any suitable material such as neoprene, EPDM, SBR, EPDM, among others.
  • the inventive surface can also provide elastomer to metal bonds described in U.S. Pat. No. 5,942,333; hereby incorporated by reference.
  • the inventive process can employ dopants, rinses, sealers and/or topcoats for providing a surface having improved thermal and wear resistance.
  • Such surfaces can be employed in gears (e.g., transmission), powdered metal articles, exhaust systems including manifolds, metal flooring/grates, heating elements, among other applications wherein it is desirable to improve the resistance of metallic surfaces.
  • the inventive process can be used to produce a surface that reduces, if not eliminates, molten metal adhesion (e.g., by reducing. intermetallic formation).
  • inventive process provides an ablative and/or a reactive film or coating upon an article or a member that can interact or react with molten metal thereby reducing adhesion to the bulk article.
  • inventive process can provide an iron or a zinc silicate film or layer upon a substrate in order to shield or isolate the substrate from molten fluid contact (e.g., molten glass, aluminum, zinc or magnesium).
  • the effectiveness of the film or layer can be improved by applying an additional coating comprising silica (e.g., to function as an ablative when exposed to molten metal or glass).
  • silica e.g., to function as an ablative when exposed to molten metal or glass.
  • the ability to prevent molten metal adhesion is desirable when die casting aluminum or magnesium over zinc cores, die casting aluminum for electronic components, among other uses.
  • the molten metal adhesion can be reduced further by applying one of the aforementioned topcoatings, e.g. Magni® B18, acrylics, polyesters, among others.
  • the topcoatings can be modified (e.g., to be more heat resistant, or reactive to alumina or aluminum) by adding a heat resistant material such as colloidal silica (e.g., Ludox®).
  • inventive process can be combined with or replace conventional metal pre or post treatment and/or finishing practices.
  • Conventional post coating baking methods can be employed for modifying the physical characteristics of the mineral layer, remove water and/or hydrogen, among other modifications.
  • inventive mineral layer can be employed to protect a metal finish from corrosion thereby replacing conventional phosphating process, e.g., in the case of automotive metal finishing the inventive process could be utilized instead of phosphates and chromates and prior to coating application e.g., E-Coat.
  • the inventive process can be employed for imparting enhanced corrosion resistance to electronic components.
  • inventive process can also be employed in a virtually unlimited array of end-uses such as in conventional plating operations as well as being adaptable to field service.
  • inventive mineral containing coating can be employed to fabricate corrosion resistant metal products that conventionally utilize zinc as a protective coating, e.g., automotive bodies and components, grain silos, bridges, among many other end-uses.
  • the inventive process can produce microelectronic films, e.g., on metal or conductive surfaces in order to impart enhanced electrical/magnetic (e.g., EMI shielding, reduced electrical connector fretting, reduce corrosion caused by dissimilar metal contact, among others), and corrosion resistance, or to resist ultraviolet light and monotomic oxygen containing environments such as outer space.
  • enhanced electrical/magnetic e.g., EMI shielding, reduced electrical connector fretting, reduce corrosion caused by dissimilar metal contact, among others
  • corrosion resistance e.g., to resist ultraviolet light and monotomic oxygen containing environments such as outer space.
  • the base silicate medium solution comprised 800 mL of distilled water+100 mL of PQ N Sodium Silicate solution (hereinafter referred to as 1:8 sodium: silicon solution).
  • the PQ N Sodium Silicate solution is 8.9 wt % Na 2 O and 28.7 wt % SiO 2 .
  • the deposition was carried out in a plating cell made of glass on ACT zinc plated steel panels. Prior to deposition the panels were degreased with acetone and washed with demineralized water. Two different sets of parameters were varied in this experiment:
  • the electrode was left on open circuit till the potential is stabilized. After the potential stabilized, non-destructive evaluation of the surface was done using linear polarization and impedance analysis. During linear polarization, the potential was varied 10 mV above and below the open circuit potential of the mineralized sample at a scan rate of 0.1667 mV/s. The impedance data generally covered a frequency range of 5 mHz to 10 kHz. A sinusoidal ac voltage signal varying by ⁇ 10 mV was applied. The electrode was stable during the experiments and its open circuit potential changed less than 1 mV.
  • FIG. 1 presents the open-circuit potential of galvanized zinc panels immersed in the base solution of pH 10.5. As seen from the plot, the potential initially increases from an initial value of around ⁇ 0.49 V to more positive values. This indicates the formation of a passive film on the surface of zinc in presence of the base solution.
  • FIG. 5 and FIG. 6 summarizes the corrosion potentials determined on galvanized steel samples in base solution at 75° and 80° C., respectively.
  • the corrosion potentials are shown as a function of time estimated in solutions with pH 10.5, 11, 11.5 and 12.
  • the results indicated that at pH 10.5 at 75° C. and 80° C. passive film forms which is stable as a function of time. Note that increasing the temperature from 75 to 80° C, the potentials estimated at pH 10.5 and 11 shifts for approximately 200 mV in cathodic direction indicating a higher probability for a decrease of the coating barrier properties.
  • FIG. 7 shows the open circuit potential studies for Zn plated steel at different pHs (10.5, 11 and 12) in the absence of base solutions. As expected the relatively high corrosion potentials (higher than ⁇ 1.0 V v. Hg/HgSO 4 reference electrode) were observed in the absence of silica in the solution indicating a high probability for Zn dissolution at pH 10.5 and higher
  • Tables 1 and 2 summarize the polarization resistance data of samples treated in accordance with the inventive mineralization process and tested at different temperatures and pH's (10.5, 10.8, 11, 11.5 and 12). Subsequent to mineralization one set of panels was rinsed immediately. The second set of samples was rinsed after 24 hours before carrying out the measurements. The rinsed panels data are presented in Table 1, while the data obtained from panels rinsed after 24 hours are presented in Table 2. In general the samples rinsed after 24 hours showed higher resistances. Increase in temperature from 75° C. to 80° C. leads to an increase in resistance. In contrast increasing the pH from 10.5 to 12 leads to a decrease in average resistance. TABLE 1 No Current Data for temperatures 75, 80, and 85° C.
  • Rp ( ⁇ ) 963 892 1252 719 710 Rp ( ⁇ ) 540 1346 1526 830 778
  • Rp ( ⁇ ) 1319 2010 1301 624 905
  • Rp ( ⁇ ) 2203 1079 975 1050
  • Rp ( ⁇ ) 3342 1951 998 898 Average 1573 1369 1388 833 845 85° C.
  • Rp ( ⁇ ) 249 1115 1887 783 Rp ( ⁇ ) 519 1323 2080
  • 1268 Rp ( ⁇ ) 1078 1124 2133
  • 1486 Rp ( ⁇ ) 1429 926 1603 1225
  • Rp ( ⁇ ) 1855 Rp ( ⁇ ) 757
  • Rp ( ⁇ ) 586 Rp ( ⁇ ) 817 Average 819 1063 1926 1191
  • Rp ( ⁇ ) 638 1457 992 1041 Rp ( ⁇ ) 648 1577 7996 3769
  • a 1:8 (alkali to silica ratio) sodium silicate solution was prepared as described in Example 1.
  • the effect of deposition time, the pH of the silicate medium and the temperature of the silicate medium were studied. Prior to deposition the panels were degreased with acetone and washed with demineralized water. The experiments were performed in duplicate. One set of panels was rinsed immediately following deposition and a second set was rinsed 24 hours later. The corrosion characteristics of the panels were tested in 0.5 M Na 2 SO 4 solution at pH 4. A representative panel area of 1 cm 2 was tested. The rest of the panel was masked with an insulating tape. A three-electrode setup was used to study the corrosion behavior of the mineralized samples.
  • Titanium coated with palladium was used as the counter electrode and Hg/Hg 2 Cl 2 was used as the reference electrode. All potentials are with respect to the Saturated Calomel electrode. Corrosion studies were done using a Scribner Associates Corrware Software with EG&G Princeton Applied Research Model 273 potentiostat/galvanostat and a Solartron 1255 frequency analyzer in accordance with conventional procedures. The electrode was left on open circuit until the potential stabilized. Non-destructive evaluation of the surface was done using linear polarization and impedance analysis. During linear polarization, the potential was varied 10 mV above and below the open circuit potential of the mineralized sample at a scan rate of 0.1667 mV/s.
  • the impedance data generally covered a frequency range of 5 mHz to 10 kHz.
  • a sinusoidal AC voltage signal varying by ⁇ 10 mV was applied.
  • the electrode was stable during the experiments and its open circuit potential changed less than 1 mV.
  • samples were prepared for scanning electron microscopy (SEM) and EDAX analysis that were obtained by using a Hitachi S-2500 Delta SEM.
  • Table 3 presents corrosion resistance data for electroless plated prepared at different bath temperatures. In general, increasing the temperature from 25° C. to 75° C. leads to an increase in resistance. However, increasing the temperature further to 85° C. results in decrease in resistance. For these samples, 75° C. is a desirable bath temperature for electroless mineralization. TABLE 3 Comparison of corrosion resistance for samples mineralized at different bath temperatures. Resistance ( ⁇ -cm 2 ) in pH 4, 0.5 M Na 2 SO 4 75° C. 85° C. 25° C.
  • Table 4 presents corrosion resistance data for electroless plated samples prepared at pH 10.5 and 11. Increasing the pH from 10.5 to 11 leads to an increase in average resistance. Samples that are rinsed after 24 hours typically exhibit better corrosion resistance than samples rinsed immediately. The same trend is observed for the samples prepared at different temperatures.
  • FIG. 8 shows a comparison of the SEM and EDAX analysis of samples rinsed immediately and rinsed after 24 hours. Samples rinsed immediately have no detectable Si on the surface whereas samples rinsed after 24 hours show 12% Si on the surface. This corresponds to the increased resistance shown in Tables 3 and 4. TABLE 4 Comparison of corrosion resistance for samples mineralized at different pH in 1:8 sodium silicate at 75° C.
  • Table 5 presents compares the corrosion resistance of samples with different deposition times. In general, the resistance ranges from 1400-1700 W-cm2. TABLE 5 Corrosion resistance for samples mineralized in 1:8 sodium silicate at 75° C. at different deposition times. Resistance ( ⁇ -cm 2 ) in pH 4, 0.5 M Na 2 SO 4 Location 5 minutes 10 minutes 15 minutes 20 minutes 1 2500 1885 2412 759 2 754 684 867 2295 3 913 2286 1686 1959 Avg. 1389 1618.3 1655 1668 High 2500 2286 2412 2295 Low 754 684 867 759
  • the mineralization bath should be heated, typically to a temperature of about 70 to 80 C.
  • rinsing the samples 24 hours after mineralization results in increased resistance measurements and higher silicon content than samples immediately rinsed after treatment.
  • the corrosion resistance of the sample verse time is optimized after approximately 15 minutes of treatment in the mineralization bath. The temperature of the bath, silicate concentration and drying regime can be employed for optimizing the corrosion resistance of the treated metal surface.
  • Table 7 shows the corrosion resistance of samples mineralized as above and heated at different temperatures for one hour. Increasing the drying temperature typically increases the average resistance. TABLE 7 Comparison of resistance for samples mineralized in 1:8 sodium silicate and heated at different post-deposition temperatures. Resistance ( ⁇ -cm 2 ) in pH 4, 0.5 M Na 2 SO 4 . Location 100° C. 125° C. 150° C. 175° C. 200° C. 1 4.4 ⁇ 10 4 702.9 8.2 ⁇ 10 4 1.2 ⁇ 10 5 2.1 ⁇ 10 5 2 4.7 ⁇ 10 4 6.8 ⁇ 10 4 8.4 ⁇ 10 4 1600 780.7 3 725.2 4.0 ⁇ 10 4 1644.3 8.2 ⁇ 10 4 2.3 ⁇ 10 4 Avg.
  • Table 9 presents corrosion resistance data for samples mineralized in different concentrations of silicate solution.
  • a series of bath solutions having differing ratios of PQ solution to water were prepared. For example, a 1:1 solution was prepared by adding 1 part PQ solution to 1 part water. Following mineralization, the samples were heated at 100° C. for 1 hour. Data representative of the results achieved are given below.
  • the corrosion resistance generally increases with bath concentration. With the 1:8 and the 1:4 baths, the corrosion resistance appears to be variable across the surface. However, with the 1:3 ratio bath and higher ratio baths, resistances in the range of 10 5 ⁇ -cm 2 are measured across the surface.
  • the dried samples can be rinsed to remove any water soluble species.
  • the rinse solution can comprise at least one composition for further modifying the dried sample (e.g., silanes, colloidal silica, among other materials).
  • Hydrogen is evolved at the surface of the cathode during electroplating and the rate of hydrogen evolution can be controlled by varying the applied potential or current. Hydrogen production also releases hydroxyl groups into the solution thereby increasing pH. However, in the case of electroless deposition, this can be accomplished through the use of selected reducing agents.
  • FIG. 9 presents the Si concentration of samples mineralized in 1500 mL of 1:3 sodium silicate in the presence of increasing amounts of sodium borohydride. Comparison of the samples dried in air with the samples heated at 175 C is shown. With samples dried in air, the Si content increases with borohydride concentration. With the heated samples, the Si content initially decreases with borohydride concentration, but no decrease is observed at borohydride concentrations greater than 5 g.
  • the stability of the coatings prepared without post-deposition heating is shown in Table 12 note as shown above post-deposition heating improves corrosion resistance).
  • the stability of the coatings is improved by the addition of sodium borohydride.
  • the corrosion resistance of the coatings prepared with 10 g of sodium borohydride drops from 1941.5 W-cm2 to 1372.1 W-cm2 after seven days, whereas the resistance of coating prepared in the absence of sodium borohydride drops from 2116.2 W-cm2 to 580 W-cm2.
  • FIG. 10 shows a plot of this data. TABLE 12 Comparison of resistance after immersion in water for surfaces mineralized in 1500 mL of 1:3 sodium silicate in the presence of various amounts of sodium borohydride.
  • FIG. 13 shows a plot of the inhibiting efficiencies from the voltammogram of FIG. 12.
  • the inhibiting efficiency typically increases with increasing sodium borohydride concentration.
  • FIG. 16 shows the CVs of the samples prepared in the presence of different amounts of sodium borohydride and air-dried for 24 hours. The current increases to the order of 1 mA after one week.
  • FIG. 17 shows the decrease in the inhibiting efficiency after one week immersion in water. Similar results are observed for the surfaces subjected to post-deposition heating at 175° C. for one hour (FIGS. 18 and 19). The change in inhibiting efficiency is the lowest for samples prepared with 10 g of sodium borohydride.
  • FIG. 20 shows SEM images of surfaces prepared in the presence of 10 g of sodium borohydride before and after immersion in water. Upon inspection one of skill in the art should notice that a 2 ⁇ m crack is observed. It will be appreciated by such a skilled artisan that such cracks facilitate the entry of water through the coating and allow attack of the underlying surface. As the cracks become large, to the order of 8-10 mm and flakes of zinc appear on the surface. EDAX on surfaces coated in the presence of different amounts of sodium borohydride and left to dry in air for 24 hours indicates that the Si content drops for all the samples, but the drop is the least for the sample prepared in the presence of 10 g of sodium borohydride (FIG. 21). Similar behavior is observed for surfaces prepared with post-deposition heating (FIG. 22).
  • the following table shows examples of the inventive process that employs a heated silicate medium for treating standard M-10 bolts.
  • the heated silicate medium comprised 10% N-Grade PQ sodium silicate solution (which comprises 2.88% SiO2, 0.90% alkali) and silica colloids that ranged in size from about 10 nm to about 1,000 nanometers (and typically 1 to 100 nm).
  • N-Grade PQ sodium silicate solution which comprises 2.88% SiO2, 0.90% alkali
  • silica colloids ranged in size from about 10 nm to about 1,000 nanometers (and typically 1 to 100 nm).
  • STANDARD M-10 BOLT RUN PARAMETER SUMMARIES Bath Number Of Total Bolt D.C. D.C. Run # Time (Min) Temp (C) CD (ASI) A:C Area Bolts Area (sq.
  • the present example illustrates the effect of post-treatment heating of the samples.
  • the edge of a 2.75 inch diameter ⁇ 6 inch long electric motor laminate core assembly comprising individual laminates (high silicon steel alloy) mechanically coined together and assembled onto a simulated shaft was treated. These laminates can be used from constructing the rotor of an electric motor.
  • Mineralization was carried out in a 1:3 ratio bath made of 1 part sodium silicate (PQ) solution and 3 parts water. The temperature of the bath was maintained at 75 C and a deposition time of 15 minutes.
  • Post treatment heating of the samples was carried out at 25 C until the sample was dry and 175 C until the sample was dry.
  • Examples 7-9 illustrate silicate media containing complexing agents and dopants. These silicate media were prepared in laboratory scale equipment.
  • a reducing agent solution comprising sodium borohydride (e.g., 4 grams of sodium borohydride dissolved in 50 ml water) can be added to solutions of Examples 7-9.

Abstract

The disclosure relates to a process for forming a deposit on the surface of a metallic or conductive surface. The process employs an electroless process to deposit a silicate containing coating or film upon a metallic or conductive surface.

Description

  • The subject matter herein claims benefit of previously filed U.S. Patent Application Serial Nos. 60/381,024, filed on May 15, 2002 and 60/310,007, filed on Aug. 03, 2002, both entitled “An Electroless Process For Treating Metallic Surfaces And Product Formed Thereby”; the disclosure of both is hereby incorporated by reference.[0001]
  • FIELD OF THE INVENTION
  • The instant invention relates to a process for forming a deposit on the surface of a metallic or conductive surface. The process employs a process to deposit, for example, a mineral containing coating or film upon a metallic, metal containing or an electrically conductive surface. BACKGROUND OF THE INVENTION [0002]
  • Silicates have been used in electrocleaning operations to clean steel, tin, among other surfaces. Electrocleaning is typically employed as a cleaning step prior to an electroplating operation. Usage of silicates as cleaners is described in “Silicates As Cleaners In The Production of Tinplate” is described by L. J. Brown in February 1966 edition of Plating; European Patent No. 00536832/EP B1 (Metallgesellschaft AG); U.S. Pat. Nos. 5,902,415, 5,352,296 and 4,492,616. [0003]
  • Processes for electrolytically forming a protective layer or film by using an anodic method are disclosed by U.S. Pat. No. 3,658,662 (Casson, Jr. et al.), and United Kingdom Patent No. 498,485. [0004]
  • U.S. Pat. No. 5,352,342 to Riffe, which issued on Oct. 4, 1994 and is entitled “Method And Apparatus For Preventing Corrosion Of Metal Structures” that describes using electromotive forces upon a zinc solvent containing paint; hereby incorporated by reference. U.S. Pat. Nos. 5,700,523, and 5,451,431; and German Patent No. 93115628 describes a processes for using alkaline metasilicates to treat metallic surfaces. [0005]
  • The disclosure of the previously identified patents and publications is hereby incorporated by reference. [0006]
  • SUMMARY OF THE INVENTION
  • The instant invention solves problems associated with conventional practices by providing an electroless process for treating metallic surfaces. By “electroless” it is meant that no current is applied from an external source (a current may be generated in-situ due to an interaction between the metallic surface and the medium). The process employs a silicate medium having a controlled and predetermined silicate concentration, temperature and pH. As a result, the silicate medium that interacts with the metallic surface to form surface having one or more improved properties. The inventive process controls the medium's characteristics and the surrounding environment in order to obtain a desired film or layer upon the metal surface, e.g, a film or layer having low surface porosity or high density. The characteristics of the film or layer can be controlled or modified by varying the temperature, pH, lattice builders (i.e., medium dopants), rate of formation, heat, pressure, pre and post treatments and silicate concentration. [0007]
  • The inventive process can form a surface comprising a mineral layer comprising an amorphous matrix surrounding or incorporating metal silicate crystals upon the substrate. The characteristics of the mineral layer are described in greater detail in the copending and commonly assigned patent applications listed below. [0008]
  • A metallic surface that is treated (e.g., forming the mineral layer) by the inventive process can possess improved corrosion resistance, increased electrical resistance, heat resistance, flexibility, resistance to stress crack corrosion, adhesion to topcoats, among other properties. The improved heat resistance broadens the range of processes that can be performed subsequent to forming the inventive layer, e.g., heat cured topcoatings, stamping/shaping, riveting, among other processes. The treated surface also imparts greater corrosion resistance (e.g., ASTM B-117), among other beneficial properties, than conventional tri-valent or hexa-valent chromate systems. The inventive process can provide a zinc-plate article having an ASTM B-117 resistance to white rust of at least about 96 hours (and normally greater than about 150 hours), and resistance to red rust of at least about 250 (and normally greater than about 400 hours). The corrosion resistance can be improved by adding a dopant to the silicate medium, using a rinse and/or applying at least one sealer/topcoating. [0009]
  • The inventive process is a marked improvement over conventional methods by obviating the need for solvents or solvent containing systems to form a corrosion resistant layer, e.g., a mineral layer. In contrast, to conventional methods the inventive process can be substantially solvent free. By “substantially solvent free” it is meant that less than about 5 wt. %, and normally less than about 1 wt. % volatile organic compounds (V.O.C.s) are present in the electrolytic environment. [0010]
  • The inventive process is also a marked improvement over conventional methods by reducing, if not eliminating, chromate and/or phosphate containing compounds (and issues attendant with using these compounds such as waste disposal, worker exposure, among other undesirable environmental impacts). While the inventive process can be employed to enhance chromated or phosphated surfaces, the inventive process can replace these surfaces with a more environmentally desirable surface. The inventive process, therefore, can be “substantially chromate free” and “substantially phosphate free” and in turn produce articles that are also substantially chromate (hexavalent and trivalent) free and substantially phosphate free. The inventive process can also be substantially free of heavy metals such as chromium, lead, cadmium, barium, among others. By substantially chromate free, substantially phosphate free and substantially heavy metal free it is meant that less than 5 wt. % and normally about 0 wt. % chromates, phosphates and/or heavy metals are present in a process for producing an article or the resultant article. [0011]
  • CROSS REFERENCE TO RELATED PATENTS AND PATENT APPLICATIONS
  • The subject matter of the instant invention is related to copending and commonly assigned WIPO Patent Application Publication No. WO 98/33960, Non-Provisional U.S. patent application Ser. Nos. 09/814,641; 08/850,323 (Now U.S. Pat. No. 6,165,257); 08/850,586 (Now U.S. Pat. No. 6,143,420); and 09/016,853 (now allowed), filed respectively on May 2, 1997 and Jan. 30, 1998, and 08/791,337 (now U.S. Pat. No. 5,938,976), filed on Jan. 31, 1997, in the names of Robert L. Heimann et al., as a continuation in part of Ser. No. 08/634,215 (filed on Apr. 18, 1996) in the names of Robert L. Heimann et al., and entitled “Corrosion Resistant Buffer System for Metal Products”, which is a continuation in part of Non-Provisional U.S patent application Ser. No. 08/476,271 (filed on Jun. 7, 1995) in the names of Heimann et al., and corresponding to WIPO Patent Application Publication No. WO 96/12770, which in turn is a continuation in part of Non-Provisional U.S. patent application Ser. No. 08/327,438 (filed on Oct. 21, 1994), now U.S. Pat. No. 5,714,093. [0012]
  • The subject matter of this invention is related to Non-Provisional patent application Ser. No. 09/016,849 (Attorney Docket No. EL004RH-1), filed on Jan. 30, 1998 and entitled “Corrosion Protective Coatings”. The subject matter of this invention is also related to Non-Provisional patent application Ser. No. 09/016,462 (Attorney Docket No. EL005NM-1), filed on Jan. 30, 1998 and entitled “Aqueous Gel Compositions and Use Thereof” (now U.S. Pat. No. 6,033,495). [0013]
  • The subject matter of this invention is also related to Non-Provisional patent application Ser. No. 09/814,641 (Attorney Docket No. EL008RH-6), filed on Mar. 22, 2001, and entitled “An Energy Enhanced Process For Treating A Conductive Surface And Products Formed Thereby” (and corresponds to PCT Patent Application Serial No. PCT/US01/09293), and Non-Provisional patent application Ser. No. ______ (Attorney Docket No. EL023RH-1), filed on Aug. 03, 2002 and entitled “An Electrolytic And Electroless Process For Treating Metallic Surfaces And Products Formed Thereby”, and Ser. No. ______ (Attorney Docket No. EL022RH-1), filed on Aug. 03, 2002 and entitled “Process For Treating A Conductive Surface And Products Formed Thereby”. [0014]
  • The disclosure of the previously identified patents, patent applications and publications is hereby incorporated by reference. [0015]
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • FIG. 1 illustrates the open-circuit potential of galvanized steel panels immersed in the inventive medium having a pH 10.5. [0016]
  • FIG. 2 illustrates the open-circuit potential of galvanized steel panels immersed in the inventive medium having a [0017] pH 11.
  • FIG. 3 illustrates the open-circuit potential of galvanized steel panels immersed in the inventive medium having a pH of 11.5. [0018]
  • FIG. 4 illustrates the open-circuit potential of galvanized steel panels immersed in the inventive medium having a [0019] pH 12.
  • FIG. 5 illustrates the corrosion potentials of galvanized steel panels immersed in the inventive medium having a temperature of 75 C and pHs of 10.5, 11, 11.5 and 12. [0020]
  • FIG. 6 illustrates the corrosion potentials of galvanized steel panesl immersed in the inventive medium having a temperature of 80 C and pHs of 10.5, 11, 11.5 and 12. [0021]
  • FIG. 7 illustrates the open circuit potential for galvanized steel panels exposed to pHs of 10.5, 11 and 12. [0022]
  • FIG. 8 illustrates a comparison of the SEM and EDAX analysis of samples exposed to the inventive medium and rinsed immediately and rinsed after 24 hours. [0023]
  • FIG. 9 illustrates a comparison of increasing amounts of sodium borohydride addition to the inventive medium. [0024]
  • FIG. 10 illustrates a comparison of corrosion resistance of samples treated with the inventive medium with sodium borohydride addition. [0025]
  • FIG. 11 illustrates a comparison of corrosion resistance of samples treated with the inventive medium with sodium borohydride addition and a thermal post-treatment. [0026]
  • FIG. 12 illustrates a voltagrams for samples treated in the inventive medium with sodium borohydride addition. [0027]
  • FIG. 13 illustrates inhibiting efficiencies based upon the voltagrams of FIG. 12. [0028]
  • FIG. 14 illustrates a voltagrams for samples treated in the inventive medium with sodium borohydride addition and a thermal post-treatment. [0029]
  • FIG. 15 illustrates inhibiting efficiencies based upon the voltagrams of FIG. 14. [0030]
  • FIG. 16 illustrates cyclic voltagrams for samples treated in the inventive medium with sodium borohydride addition. [0031]
  • FIG. 17 illustrates inhibiting efficiencies based upon the voltagrams of FIG. 16. [0032]
  • FIG. 18 illustrates the affect on inhibiting efficiencies on air dried samples after immersion in water for one week. [0033]
  • FIG. 19 illustrates the affect on inhibiting efficiencies on samples having a thermal post-treatment after immersion in water for one week. [0034]
  • FIG. 20 illustrates an SEM image of samples treated with the inventive medium with sodium borohydride addition before and after immersion in water. [0035]
  • FIG. 21 illustrates an EDAX of samples treated with the inventive medium with sodium borohydride addition. [0036]
  • FIG. 22 illustrates an EDAX of samples treated with the inventive medium with sodium borohydride addition and a thermal post treatment.[0037]
  • DETAILED DESCRIPTION
  • The instant invention relates to a process for depositing or forming a beneficial surface (e.g., a mineral containing coating or film) upon a metallic surface. The process contacts at least a portion of a metal surface with a silicate medium, e.g., containing soluble mineral components or precursors thereof, having controlled and predetermined silicate concentration, temperature and pH. By “mineral containing coating”, “mineralized film” or “mineral” it is meant to refer to a relatively thin coating or film which is formed upon a metal surface wherein at least a portion of the coating or film comprises at least one metal containing mineral, e.g., an amorphous phase or matrix surrounding or incorporating crystals comprising a zinc disilicate. Mineral and Mineral Containing are defined in the previously identified Cross Reference To Related Patents and Paten Applications; incorporated by reference. [0038]
  • By “metal containing”, “metal”, or “metallic”, it is meant to refer to sheets, shaped articles, fibers, rods, particles, continuous lengths such as coil and wire, metallized surfaces, among other configurations that are based upon at least one metal and alloys including a metal having a naturally occurring, or chemically, mechanically or thermally modified surface. Typically a naturally occurring surface upon a metal will comprise a thin film or layer comprising at least one oxide, hydroxides, carbonates, sulfates, chlorides, among others. The naturally occurring surface can be removed or modified by using the inventive process. [0039]
  • The metal surface refers to a metal article or body as well as a non-metallic member having an adhered metal or conductive layer. While any suitable surface can be treated by the inventive process, examples of suitable metal surfaces comprise at least one member selected from the group consisting of galvanized surfaces, sheradized surfaces, zinc, iron, steel, brass, copper, nickel, tin, aluminum, lead, cadmium, magnesium, alloys thereof such as zinc-nickel alloys, tin-zinc alloys, zinc-cobalt alloys, zinc-iron alloys, among others. If desired, the mineral layer can be formed on a non-conductive substrate having at least one surface coated with a metal, e.g., a metallized polymeric article or sheet, ceramic materials coated or encapsulated within a metal, among others. Examples of metallized polymer comprise at least one member selected from the group of polycarbonate, acrylonitrile butadiene styrene (ABS), rubber, silicone, phenolic, nylon, PVC, polyimide, melamine, polyethylene, polyproplyene, acrylic, fluorocarbon, polysulfone, polyphenyene, polyacetate, polystyrene, epoxy, among others. Conductive surfaces can also include carbon or graphite as well as conductive polymers (polyaniline for example). [0040]
  • The metal surface can possess a wide range of sizes and configurations, e.g., fibers, coils, sheets including perforated acoustic panels, chopped wires, drawn wires or wire strand/rope, rods, couplers (e.g., hydraulic hose couplings), fibers, particles, fasteners (including industrial and residential hardware), brackets, nuts, bolts, rivets, washers, cooling fins, stamped articles, powdered metal articles, among others. The limiting characteristic of the inventive process to treat a metal surface is dependent upon the ability of the surface to be contacted with the inventive silicate medium. [0041]
  • The inventive process can be operated on a batch or continuous basis. The type of process will depend upon the configuration of the metal being treated. The contact time within the silicate medium ranges from about 10 seconds to about 50 minutes and normally about 1 to about 15 minutes. The inventive process can be practiced in any suitable apparatus. Examples of suitable apparatus comprise a batch process performed in polyproplyene tanks having means for circulating the silicate medium and maintaining a predetermined temperature. [0042]
  • The silicate containing medium can be a fluid bath, gel, spray, fluidized beds, among other methods for contacting the substrate with the silicate medium. Examples of the silicate medium comprise a bath containing at least one silicate, a gel comprising at least one silicate and a thickener, among others. The medium can comprise a bath comprising at least one of potassium silicate, calcium silicate, lithium silicate, sodium silicate, ammonium silicate, compounds releasing silicate moieties or species, among other silicates. The bath can comprise any suitable polar or non-polar carrier such as water, alcohol, ethers, carboxillic acids, among others. Normally, the bath comprises at least one water-soluble silicate such as sodium silicate and de-ionized water and optionally at least one dopant (e.g. chlorides among other monovalent species). Typically, the at least one dopant is water soluble or dispersible within an aqueous medium. [0043]
  • The silicate containing medium typically has a basic pH. Normally, the pH will range from greater than about 9 to about 13 and typically, about 10 to about 12. The pH of the medium can be monitored and maintained by using conventional detection and delivery methods. The selected detection method should be reliable at relatively high sodium concentrations and under ambient conditions. [0044]
  • The silicate medium is normally aqueous and can comprise at least one water soluble or dispersible silicate in an amount from greater than about 0 to about 40 wt. %, usually, about 1 to 15 wt. % and typically about 3 to 8 wt. %. The amount of silicate in the medium should be adjusted to accommodate silicate sources having differing concentrations of silicate. The silicate containing medium is also normally substantially free of heavy metals, chromates and/or phosphates. [0045]
  • The silicate medium can be modified by adding at least one stabilizing compound (e.g., stabilizing by complexing metals). An example of a suitable stabilizing compound comprises phosphines, sodium citrate, ammonium citrate, ammonium iron citrate, sodium salts of ethylene diamine tetraacetic acid (EDTA) and nitrilotriacetic acid (NTA), 8-hydroxylquinoline, 1,2-diaminocyclohexane-tetracetyic acid, diethylene-triamine pentacetic acid, ethylenediamine tetraacetic acid, ethylene glycol bisaminoethyl ether tetraacetic acid, ethyl ether diaminetetraacetic acid, N′-hydroxyethylethylenediamine triacetic acid, 1-methyl ethylene diamine tetraacetic acid, nitriloacetic acid, pentaethylene hexamine, tetraethylene pentamine, triethylene tetraamine, among others. [0046]
  • In one aspect, the silicate medium has a basic pH and comprises at least one water soluble silicate, water and colloidal silica. The silicate medium can also be modified by adding colloidal particles such as colloidal silica (commercially available as Ludox® AM-30, HS-40, among others). The colloidal silica has a particle size ranging from about 10 nm to about 50 nm. The size of particles in the medium ranges from about 10 nm to 1 micron and typically about 0.05 to about 0.2 micron. The medium has a turbidity of about 10 to about 700, typically about 50 to about 300 Nephelometric Turbidity Units (NTU) (as determined in accordance with conventional procedures). [0047]
  • The temperature of the silicate medium can be controlled to optimize the interaction between the medium and a metal surface. Normally, the temperature will range from about 50 to at least about 100 C and typically about 50 to 100 C (e.g., 55 C). This temperature can be maintained by using conventional heaters and related control systems. If desired, the metal surface can be heated prior to being introduced into the medium. [0048]
  • The chemical and/or physical properties of the silicate medium can be affected by exposing the medium to a source of electrical or magnetic energy. For example, the bath can be exposed to a source of energy such as the electrical current described in aforementioned U.S. Ser. No. 09/814,641; hereby incorporated by reference. Such exposure can improve the interaction between the medium and the metal surface, partially polymerize the silicate medium, partially crystallize the silicate medium, among other affects. [0049]
  • The silicate medium can be modified by adding water/polar carrier dispersible or soluble polymers. If utilized, the amount of polymer or water dispersible materials normally ranges from about 0 wt. % to about 10 wt. %. Examples of polymers or water dispersible materials that can be employed in the silicate medium comprise at least one member selected from the group of acrylic copolymers (supplied commercially as Carbopol®), zirconyl ammonium carbonate, hydroxyethyl cellulose, clays such as bentonite, fumed silica, solutions comprising sodium silicate (supplied commercially by MacDermid as JS2030S), among others. A suitable composition can be obtained in an aqueous composition comprising about 3 wt % silicate (obtained from N-grade Sodium Silicate Solution (PQ Corp) that comprises 25% silicate), optionally about 0.5 wt % Carbopol EZ-2 (BF Goodrich), about 5 to about 10 wt. % fumed silica, mixtures thereof, among others. [0050]
  • In an aspect of the invention, the silicate medium is modified to include at least one dopant material. The dopants can be useful for building additional thickness of the deposited layer, hydroxides of iron, aluminum, manganise, and magnesium among others. The amount of dopant can vary depending upon the properties of the dopant and desired results. Typically, the amount of dopant will range from about 0.001 wt. % to about 5 wt. % of the medium (or greater so long as the deposition rate is not adversely affected). Examples of suitable dopants comprise at least one member selected from the group of water dispersible or soluble salts, oxides and precursors of tungsten, molybdenum (e.g., molybdenum chloride), titanium (titatantes), zircon, vanadium, phosphorus, aluminum (e.g., aluminates, aluminum chloride, etc), iron (e.g., iron chloride), boron (borates), bismuth, cobalt (e.g., cobalt chloride, cobalt oxide, etc.), gallium, tellurium, germanium, antimony, niobium (also known as columbium), magnesium and manganese, nickel (e.g., nickel chloride, nickel oxide, etc.), sulfur, zirconium (zirconates) mixtures thereof, among others, and usually, salts and oxides of aluminum and iron, and hydroxides of iron, aluminum, manganese and magnesium, among others; and other water soluble or dispersible monovalent species. The dopant can comprise at least one of molybdenic acid, fluorotitanic acid and salts thereof such as titanium hydrofluoride, ammonium fluorotitanate, ammonium fluorosilicate and sodium fluorotitanate; fluorozirconic acid and salts thereof such as H[0051] 2ZrF6, (NH4)2ZrF6 and Na2ZrF6; among others. Alternatively, dopants can comprise at least one substantially water insoluble material such as electropheritic transportable polymers, PTFE, boron nitride, silicon carbide, silicon nitride, aluminum nitride, titanium carbide, diamond, titanium diboride, tungsten carbide, silica (e.g., colloidal silica available commercially as Ludox® AM and HS) metal oxides such as cerium oxide, powdered metals and metallic precursors such as zinc, among others.
  • If desired, the dopant can be dissolved or dispersed without another medium prior to introduction into the silicate medium. For example, at least one dopant can be combined with a basic compound, e.g., sodium hydroxide, and then added to the silicate medium. Examples of dopants that can be combined with another medium comprise zirconia, cobalt oxide, nickel oxide, molybdenum oxide, titanium (IV) oxide, niobium (V) oxide, magnesia, zirconium silicate, alumina, antimony oxide, zinc oxide, zinc powder, aluminum powder, among others. [0052]
  • The aforementioned dopants that can be employed for enhancing mineral layer formation rate, modifying the chemistry and/or physical properties of the resultant layer, as a diluent for the silicate containing medium, among others. Examples of such dopants are iron salts (ferrous chloride, sulfate, nitrate), aluminum fluoride, fluorosilicates (e.g., K2SiF6), fluoroaluminates (e.g., potassium fluoroaluminate such as K2AlF5-H2O), mixtures thereof, among other sources of metals and halogens. The dopant materials can be introduced to the metal surface in pretreatment steps, in post treatment steps (e.g., rinse), and/or by alternating exposing the metal surface to solutions of dopants and solutions of silicates if the silicates will not form a stable solution with the dopants, e.g., one or more water soluble dopants. The presence of dopants in the silicate medium can be employed to form tailored surfaces upon the metal, e.g., an aqueous sodium silicate solution containing aluminate can be employed to form a layer comprising oxides of silicon and aluminum. That is, at least one dopant (e.g., zinc) can be co-deposited along with at least one siliceous species (e.g., a mineral) upon the substrate. [0053]
  • The silicate medium can also be modified by adding at least one diluent. Examples of suitable diluent comprise at least one member selected from the group of sodium sulphate, surfactants, de-foamers, colorants/dyes, conductivity modifiers, among others. The diluent (e.g., sodium sulfate) can be employed for reducing the affects of contaminants entering the silicate medium, reducing bath foam, among others. When the diluent is employed as a defoamer, the amount normally comprises less than about 5 wt. % of the medium, e.g., about 1 to about 2 wt. %. [0054]
  • According to one embodiment of the invention, the silicate medium further comprises at least one reducing agent. An example of a suitable reducing agent comprises sodium borohydride, phosphorus compounds such as hypophosphide compounds, phosphate compounds, among others. Without wishing to be bound by any theory or explanation, it is believed that the reducing agent may reduce water present in the silicate medium thereby modifying the surface pH of articles that contact the silicate medium (e.g., article may induce or catalyze activity of the reducing agent). According to one embodiment, the concentration of sodium borohydride is typically 1 gram per liter of bath solution to about 20 grams per liter of bath solution more typically 5 grams per liter of bath solution to about 15 gram per liter of bath solution. In one illustrative and preferred embodiment, 10 grams of sodium borohydride per liter of bath solution is utilized. When employed the reducing agent, can cause hydrogen evolution once the bath/medium has been sufficiently heated. [0055]
  • Contact with the inventive silicate medium can be preceded by and/or followed with conventional pre-treatments and/or post-treatments known in this art such as cleaning or rinsing, e.g., immersion/spray within the treatment, sonic cleaning, double counter-current cascading flow; alkali or acid treatments, among other treatments. By employing a suitable post-treatment the solubility, corrosion resistance (e.g., reduced white rust formation when treating zinc containing surfaces), sealer and/or topcoat adhesion, among other properties of surface of the substrate formed by the inventive method can be improved. If desired, the post-treated surface can be sealed, rinsed and/or topcoated, e.g., silane, epoxy, latex, fluoropolymer, acrylic, titanates, zirconates, carbonates, urethanes, among other coatings. [0056]
  • In one aspect of the invention, a pre-treatment comprises exposing the substrate to be treated to at least one of an acid, base (e.g., zincate solution), oxidizer, among other compounds. The pre-treatment can be employed for cleaning oils, removing excess oxides or scale, equipotentialize the surface for subsequent mineralization treatments, convert the surface into a mineral precursor, functionalize the surface (e.g., a hydroxilized surface), among other benefits. Conventional methods for acid cleaning metal surfaces are described in ASM, Vol. 5, Surface Engineering (1994), and U.S. Pat. No. 6,096,650; hereby incorporated by reference. [0057]
  • In one aspect of the invention, the metal surface is pre-treated or cleaned electrolytically by being exposed to an anodic environment. That is, the metal surface is exposed to the silicate medium wherein the metal surface is the anode and a current is introduced into the medium. By using the metal as the anode in a DC cell and maintaining a current of about 10 A/ft2 to about 150 A/ft2, the process can generate oxygen gas. The oxygen gas agitates the surface of the workpiece while oxidizing the substrate's surface. The surface can also be agitated mechanically by using conventional vibrating equipment. If desired, the amount of oxygen or other gas present during formation of the mineral layer can be increased by physically introducing such gas, e.g., bubbling, pumping, among other means for adding gases. [0058]
  • If desired, the inventive method can include a thermal post-treatment. The metal surface can be removed from the silicate medium, dried (e.g., at about 100 to 150 C for about 2.5 to 10 minutes), rinsed in deionized water and then dried in order to remove rinse water. This is in contrast to conventional metal treatments that rinse(s) and then dry. The dried surface may be processed further as desired; e.g. contacted with a sealer, rinse or topcoat. If desired, the rinse can comprise a reactive component such as a silane, carbonate, zirconate, colloidal silica, among other compounds that interact with the treated metallic surface. [0059]
  • In aspect of the invention, the thermal post treatment comprises heating the surface. Typically the amount of heating is sufficient to consolidate or densify the inventive surface without adversely affecting the physical properties of the underlying metal substrate. Heating can occur under atmospheric conditions, within a nitrogen containing environment, among other gases. Alternatively, heating can occur in a vacuum. The surface may be heated to any temperature within the stability limits of the surface coating and the surface material. Typically, surfaces are heated from about 75° C. to about 250° C., more typically from about 150° C. to about 200° C. If desired, the heat treated component can be rinsed in water to remove any residual water soluble species and then dried again (e.g., at a temperature and time sufficient to remove water). [0060]
  • If desired, prior to heating the inventive surface can be contacted with a solution containing a material that reacts with the surface at elevated temperatures, e.g., a eutectic formed between silica and at least one of Al2O3, B2O3, Fe2O3, MgO, phosphates, among others. Normally, the heating will be sufficient to cause sintering or a desirable interaction without adversely affecting the underlying metal. Alternatively or in addition to heating, the metal surface can be exposed to an atmosphere having controlled pressure in order to tailor the treated surface. [0061]
  • In one aspect of the invention, a post treatment comprises exposing the substrate to a source of at least one carbonate or precursors thereof. Examples of carbonate comprise at least one member from the group of gaseous carbon dioxide, lithium carbonate, lithium bicarbonate, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, rubidium carbonate, rubidium bicarbonate, rubidium acid carbonate, cesium carbonate, ammonium carbonate, ammonium bicarbonate, ammonium carbamate and ammonium zirconyl carbonate. Normally, the carbonate source will be water soluble. In the case of a carbonate precursor such as carbon dioxide, the precursor can be passed through a liquid (including the silicate containing medium) and the substrate immersed in the liquid. One specific example of a suitable postreatment is disclosed in U.S. Pat. No. 2,462,763; hereby incorporated by reference. Another specific example of a post treatment comprises exposing a treated surface to a solution obtained by diluting ammonium zirconyl carbonate (1:4) in distilled water (e.g., [0062] Bacote® 20 supplied by Magnesium Elektron Corp). If desired, this post treated surface can be topcoated (e.g., aqueous or water borne topcoats).
  • In another aspect of the invention, the post treatment comprises exposing the substrate to a source comprising at least one acid source or precursors thereof. Examples of suitable acid sources comprise at least one member chosen from the group of phosphoric acid, hydrochloric acid, molybdic acid, silicic acid, acetic acid, citric acid, nitric acid, hydroxyl substituted carboxylic acid, glycolic acid, lactic acid, malic acid, tartaric acid, ammonium hydrogen citrate, ammonium bifluoride, fluoboric acid, fluorosilicic acid, among other acid sources effective at improving at least one property of the treated metal surface. The pH of the acid post treatment may be modified by employing at least one member selected from the group consisting of ammonium citrate dibasic (available commercially as Citrosol® #503 and Multiprep®), fluoride salts such as ammonium bifluoride, fluoboric acid, fluorosilicic acid, among others. The acid post treatment can serve to activate the surface thereby improving the effectiveness of rinses, sealers and/or topcoatings (e.g., surface activation prior to contacting with a sealer can improve cohesion between the surface and the sealer thereby improving the corrosion resistance of the treated substrate). Normally, the acid source will be water soluble and employed in amounts of up to about 15 wt. % and typically, about 1 to about 5 wt. % and have a pH of less than about 5.5. [0063]
  • In another aspect of the invention, the post treatment comprises contacting a surface treated by the inventive process with a rinse. By “rinse” it is meant that an article or a treated surface is sprayed, dipped, immersed or other wise exposed to the rinse in order to affect the properties of the treated surface. For example, a surface treated by the inventive process is immersed in a bath comprising at least one rinse. In some cases, the rinse can interact or react with at least a portion of the treated surface. Further the rinsed surfaced can be modified by multiple rinses, heating, topcoating, adding dyes, lubricants and waxes, among other processes. Examples of suitable compounds for use in rinses comprise at least one member selected from the group of titanates, titanium chloride, tin chloride, zirconates, zirconium acetate, zirconium oxychloride, fluorides such as calcium fluoride, tin fluoride, titanium fluoride, zirconium fluoride; coppurous compounds, ammonium fluorosilicate, metal treated silicas (e.g., Ludox®), combinations comprising colloidal silica, nitrates such as aluminum nitrate; sulphates such as magnesium sulphate, sodium sulphate, zinc sulphate, silanes, siloxyanes, siloxyenes, and copper sulphate; lithium compounds such as lithium acetate, lithium bicarbonate, lithium citrate, lithium metaborate, lithium vanadate, lithium tungstate, among others. The rinse can further comprise at least one organic compound such as vinyl acrylics, fluorosurfactancts, polyethylene wax, TEOS, zirconyl ammonium carbonate, among others. Examples of commercially available rinses, sealers and topcoats comprise at least one member selected from the group of Aqualac® (urethane containing aqueous solution), W86®, W87®, B37®, T01®, E10®, B17, B18 among others (a heat cured coating supplied by the Magni® Group), JS2030S (sodium silicate containing rinse supplied by MacDermid Incorporated), JS20401 (a molybdenum containing rinse also supplied by MacDermid Incorporated), EnSeal® C-23 (an acrylic based coating supplied by Enthone), EnSeal® C-26, Enthone® C-40 (a pigmented coating supplied Enthone), Microseal®, Paraclene® 99 (a chromate containing rinse), EcoTri® (a silicate/polymer rinse), MCI Plus OS (supplied by Metal Coatings International), silanes (e.g., Dow Corning Z-6040, Gelest SIA 0610.0, among others), ammonium zirconyl carbonate (e.g., Bacote 20), urethanes (e.g., Agate L18), among others. One specific rinse comprises water, water dispersible urethane, and at least one silicate, e.g., refer to commonly assigned U.S. Pat. No. 5,871,668; hereby incorporated by reference. While the rinse can be employed neat, normally the rinse will be dissolved, diluted or dispersed within another medium such as water, organic solvents, among others. While the amount of rinse employed depends upon the desired results, normally the rinse comprises about 0.1 wt % to about 50 wt. % of the rinse medium. The rinse can be employed as multiple applications and, if desired, heated. The rinse can be employed after a thermal treatment, e.g., after removing from the silicate medium the part is dried and then rinsed. Moreover, the aforementioned rinses can be modified by incorporating at least one dopant, e.g. the aforementioned dopants. The dopant can employed for interacting or reacting with the treated surface. If desired, the dopant can be dispersed in a suitable medium such as water and employed as a rinse. [0064]
  • The inventive process can create a flexible surface that can survive secondary processes, e.g., metal deformation for riveting, sweging, crimping, among other processes, and continue to provide corrosion protection. Such is in contrast to typical corrosion inhibitors such as chromates that tend to crack when the underlying surface is shaped. If desired, the surface formed by the inventive process can be topcoated (e.g, with a heat cured epoxy), prior to secondary processing. Articles treated in accordance with the inventive process, topcoated and exposed to a secondary process retain their desirable corrosion resistance, coating adhesion, component functionality, among properties. [0065]
  • The inventive process can provide a surface (e.g., mineral coating) that can enhance the surface characteristics of the metal or conductive surface such as resistance to corrosion, protect carbon (fibers for example) from oxidation, stress crack corrosion (e.g., stainless steel), hardness, thermal resistance, improve bonding strength in composite materials, provide dielectric layers, improve corrosion resistance of printed circuit/wiring boards and decorative metal finishes, and reduce the conductivity of conductive polymer surfaces including application in sandwich type materials. [0066]
  • The mineral coating can also affect the electrical and magnetic properties of the surface. That is, the mineral coating can impart electrical resistance or insulative properties to the treated surface. By having an electrically non-conductive surface, articles having the inventive layer can reduce, if not eliminate, electro-galvanic corrosion in fixtures wherein current flow is associated with corrosion, e.g., bridges, pipelines, among other articles. [0067]
  • Depending upon the intended usage of the workpiece treated by the inventive method, the workpiece can be coated with a secondary coating or layer. Alternatively, the treated workpiece can be rinsed (as described above) and then coated with a secondary coating or layer. Examples of such secondary coatings or layers comprise one or more members of acrylic coatings (e.g., IRILAC®), e-coats, silanes including those having amine, acrylic and aliphatic epoxy functional groups, latex, urethane, epoxies, silicones, alkyds, phenoxy resins (powdered and liquid forms), radiation curable coatings (e.g., UV curable coatings), lacquer, shellac, linseed oil, among others. Secondary coatings can be solvent or water borne systems. Secondary coatings can also include corrosion inhibitors, torque tension modifiers, among other additives (e.g., a coating comprising urethanes, acrylics, corrosion inhibitor and sodium silicate). The secondary coatings can be applied by using any suitable conventional method such as immersing, dip-spin, spraying, among other methods. The secondary coatings can be cured by any suitable method such as UV exposure, heating, allowed to dry under ambient conditions, among other methods. An example of UV curable coating is described in U.S. Pat. Nos. 6,174,932 and 6,057,382; hereby incorporated by reference. Normally, the surface formed by the inventive process will be rinsed, e.g., with at least one of deionized water, silane or a carbonate, or subjected to a thermal treatment (e.g., removal from the silicate bath, dried and then rinsed to remove residual material), prior to applying a topcoat. The secondary coatings can be employed for imparting a wide range of properties such as improved corrosion resistance to the underlying mineral layer, reduce torque tension, a temporary coating for shipping the treated workpiece, decorative finish, static dissipation, electronic shielding, hydrogen and/or atomic oxygen barrier, among other utilities. The mineral coated metal, with or without the secondary coating, can be used as a finished product or a component to fabricate another article. [0068]
  • The thickness of the rinse, sealer and/or topcoat can range from about 0.00001 inch to about 0.025 inch. The selected thickness varies depending upon the end use of the coated article. In the case of articles having close dimensional tolerances, e.g., threaded fasteners, normally the thickness is less than about 0.00005 inch. [0069]
  • Without wishing to be bound by any theory or explanation a silica containing layer can be formed. By silica it is meant a framework of interconnecting molecular silica such as SiO4 tetrahedra (e.g., amorphous silica, cristabalite, triydmite, quartz, among other morphologies depending upon the degree of crystalinity), monomeric or polymeric species of silicon and oxide, monomeric or species of silicon and oxide embedding colloidal species, among others. The crystalinity of the silica can be modified and controlled depending upon the conditions under which the silica is deposited, e.g., temperature and pressure. The silica containing layer may comprise: 1) low porosity silica (e.g., about 60 angstroms to 0.5 microns in thickness), 2) collodial silica (e.g., about 50 angstroms to 0.5 microns in thickness), 3) a mixture comprising 1 and 2, 4) residual silicate such as sodium silicate and in some cases combined with 1 and 2; and 5) monomeric or polymeric species optionally embedding other colloidal silica species such as colloidal silica. The formation of a silica containing layer can be enhanced by the addition of colloidal particles to the silicate medium. An example of suitable colloidal particles comprise colloidal silica having a size of at least about 12 nanometers to about 0.1 micron (e.g., [0070] Ludox® HS 40, AM 30, and CL). The colloidal silica can be stabilized by the presence of metals such as sodium, aluminum/alumina, among others.
  • If desired, the silica containing film or layer can be provided in as a secondary process. That is, a first film or layer comprising a disilicate can be formed upon the metallic surface and then a silica containing film or layer is formed upon the disilicate surface. An example of this process is described in U.S. Patent Application Serial No. 60/354,565, filed on Feb. 05, 2002 and entitled “Method for Treating Metallic Surfaces”; the disclosure of which is hereby incorporated by reference. [0071]
  • The silica containing layer can be chemically or physically modified and employed as an intermediate or tie-layer. The tie-layer can be used to enhance bonding to paints, coatings, metals, glass, among other materials contacting the tie-layer. This can be accomplished by binding to the top silica containing layer one or more materials which contain alkyl, fluorine, vinyl, epoxy including two-part epoxy and powder paint systems, silane, hydroxy, amino, mixtures thereof, among other functionalities reactive to silica or silicon hydroxide. Alternatively, the silica containing layer can be removed by using conventional cleaning methods, e.g, rinsing with de-ionized water, or one of the aforementioned post-treatments, e.g. acid rinsing. If desired, the silica containing layer can be chemically and/or physically modified by employing the previously described post-treatments, e.g., exposure to at least one carbonate or acid source. The post-treated surface can then be contacted with at least one of the aforementioned secondary coatings, e.g, a heat cured epoxy. [0072]
  • In another aspect, the mineral without or without the aforementioned silica may layer functions as an intermediate or tie-layer for one or more secondary coatings, e.g., silane containing secondary coatings. Examples of such secondary coatings and methods that can be complimentary to the instant invention are described in U.S. Pat. Nos. 5,759,629; 5,750,197; 5,539,031; 5,498,481; 5,478,655; 5,455,080; and 5,433,976. The disclosure of each of these U.S. Patents is hereby incorporated by reference. For example, improved corrosion resistance of a metal substrate can be achieved by using a secondary coating comprising at least one suitable silane in combination with a mineralized surface. Examples of suitable silanes comprise at least one members selected from the group consisting of tetraethylorthosilicate (TEOS) and TMOS with styrene, and etc., bis-1,2-(triethoxysilyl) ethane (BSTE), vinyl silane or aminopropyl silane, epoxy silanes, alkoxysilanes, methacryloxypropyl trimethoxysilanes, glycidoxypropyl trimethoxysilane, vinyltriactoxysilane, among other organo functional silanes. The silane can bond with the mineralized surface and then the silane can cure thereby providing a protective top coat, or a surface for receiving an outer coating or layer. In some cases, it is desirable to sequentially apply the silanes. For example, a steel substrate, e.g., a fastener, can be treated by the inventive process to form a mineral layer, allowed to dry, rinsed in deionized water, coated with a 5% BSTE solution, coated again with a 5% vinyl silane solution, and powder coated with a thermoset epoxy paint (Corvel 10-1002 by Morton) at a thickness of 2 mils. [0073]
  • The inventive process forms a surface that has improved adhesion to outer coatings or layers, e.g., secondary coatings. Examples of suitable outer coatings comprise at least one member selected from the group consisting of acrylics, epoxies, e-coats, latex, urethanes, silanes (e.g., TEOS, TMEOS, among others), fluoropolymers, alkyds, silicones, polyesters, oils, gels, grease, among others. An example of a suitable epoxy comprises a coating supplied by The Magni® Group as B17 or B18 top coats, e.g, a galvanized article that has been treated in accordance with the inventive method and contacted with at least one silane and/or ammonium zirconium carbonate and top coated with a heat cured epoxy (Magni® B18) thereby providing a chromate free corrosion resistant article. By selecting appropriate rinses, secondary and outer coatings for application upon the mineral, a corrosion resistant article can be obtained without chromating or phosphating. Such a selection can also reduce usage of zinc to galvanize iron containing surfaces, e.g., a steel surface is mineralized, coated with a silane containing coating and with an outer coating comprising an epoxy. [0074]
  • Without wishing to be bound by any theory or explanation, it is believed that the inventive process forms a surface that can release or provide water or related moieties. These moieties can participate in a hydrolysis or condensation reaction that can occur when an overlying rinse, seal or topcoating cures. Such participation improves the cohesive bond strength between the surface and overlying cured coating. [0075]
  • The surface formed by the inventive process can also be employed as an intermediate or tie-layer for glass coatings, glass to metal seals, hermetic sealing, among other applications wherein it is desirable to have a joint or bond between a metallic substrate and a glass layer or article. The inventive surface can serve to receive molten glass (e.g., borosilicate, aluminosilicate, phosphate, among other glasses), while protecting the underlying metallic substrate and forming a seal. [0076]
  • The surface formed by the inventive process can also be employed as a heat resistant surface. The surface can be employed to protect an underlying surface from exposure to molten metal (e.g., molten aluminum). [0077]
  • The inventive process can provide a surface that improves adhesion between a treated substrate and an adhesive. Examples of adhesives comprise at least one member selected from the group consisting of hot melts such as at least one member selected from the group of polyamides, polyimides, butyls, acrylic modified compounds, maleic anhydride modified ethyl vinyl acetates, maleic anhydride modified polyethylenes, hydroxyl terminated ethyl vinyl acetates, carboxyl terminated ethyl vinyl acetates, acid terpolymer ethyl vinyl acetates, ethylene acrylates, single phase systems such as dicyanimide cure epoxies, polyamide cure systems, lewis acid cure systems, polysulfides, moisture cure urethanes, two phase systems such as epoxies, activated acrylates polysulfides, polyurethanes, among others. Two metal substrates having surfaces treated in accordance with the inventive process can be joined together by using an adhesive. Alternatively one substrate having the inventive surface can be adhered to another material, e.g., joining treated metals to plastics, ceramics, glass, among other surfaces. In one specific aspect, the substrate comprises an automotive hem joint wherein the adhesive is located within the hem. [0078]
  • The improved cohesive and adhesive characteristics between a surface formed by the inventive process and polymeric materials can permit forming acoustical and mechanical dampeners, e.g., constraint layer dampers such as described in U.S. Pat. No. 5,678,826 hereby incorporated by reference, motor mounts, bridge/building bearings, HVAC silencers, highway/airport sound barriers, among other articles. The ability to improve the bond between vistoelastomeric materials sandwiched between metal panels in dampers reduces sound transmission, improves formability of such panels, reduces process variability, among other improvements. The metal panels can comprise any suitable metal such as 304 steel, stainless steel, aluminum, cold rolled steel, zinc alloys, hot dipped zinc or electrogalvanized, among other materials. Examples of polymers that can be bonded to the inventive surface and in turn to an underlying metal substrate comprise any suitable material such as neoprene, EPDM, SBR, EPDM, among others. The inventive surface can also provide elastomer to metal bonds described in U.S. Pat. No. 5,942,333; hereby incorporated by reference. [0079]
  • The inventive process can employ dopants, rinses, sealers and/or topcoats for providing a surface having improved thermal and wear resistance. Such surfaces can be employed in gears (e.g., transmission), powdered metal articles, exhaust systems including manifolds, metal flooring/grates, heating elements, among other applications wherein it is desirable to improve the resistance of metallic surfaces. [0080]
  • In another aspect of the invention, the inventive process can be used to produce a surface that reduces, if not eliminates, molten metal adhesion (e.g., by reducing. intermetallic formation). Without wishing to be bound by any theory or explanation, it is believed that the inventive process provides an ablative and/or a reactive film or coating upon an article or a member that can interact or react with molten metal thereby reducing adhesion to the bulk article. For example, the inventive process can provide an iron or a zinc silicate film or layer upon a substrate in order to shield or isolate the substrate from molten fluid contact (e.g., molten glass, aluminum, zinc or magnesium). The effectiveness of the film or layer can be improved by applying an additional coating comprising silica (e.g., to function as an ablative when exposed to molten metal or glass). The ability to prevent molten metal adhesion is desirable when die casting aluminum or magnesium over zinc cores, die casting aluminum for electronic components, among other uses. The molten metal adhesion can be reduced further by applying one of the aforementioned topcoatings, e.g. Magni® B18, acrylics, polyesters, among others. The topcoatings can be modified (e.g., to be more heat resistant, or reactive to alumina or aluminum) by adding a heat resistant material such as colloidal silica (e.g., Ludox®). [0081]
  • While the above description places particular emphasis upon forming a mineral containing layer upon a metal surface, the inventive process can be combined with or replace conventional metal pre or post treatment and/or finishing practices. Conventional post coating baking methods can be employed for modifying the physical characteristics of the mineral layer, remove water and/or hydrogen, among other modifications. The inventive mineral layer can be employed to protect a metal finish from corrosion thereby replacing conventional phosphating process, e.g., in the case of automotive metal finishing the inventive process could be utilized instead of phosphates and chromates and prior to coating application e.g., E-Coat. The inventive process can be employed for imparting enhanced corrosion resistance to electronic components. The inventive process can also be employed in a virtually unlimited array of end-uses such as in conventional plating operations as well as being adaptable to field service. For example, the inventive mineral containing coating can be employed to fabricate corrosion resistant metal products that conventionally utilize zinc as a protective coating, e.g., automotive bodies and components, grain silos, bridges, among many other end-uses. Moreover, depending upon the dopants and concentration thereof present in the mineral deposition solution, the inventive process can produce microelectronic films, e.g., on metal or conductive surfaces in order to impart enhanced electrical/magnetic (e.g., EMI shielding, reduced electrical connector fretting, reduce corrosion caused by dissimilar metal contact, among others), and corrosion resistance, or to resist ultraviolet light and monotomic oxygen containing environments such as outer space. [0082]
  • The following Examples are provided to illustrate certain aspects of the invention and it is understood that such an Example does not limit the scope of the invention. [0083]
  • EXAMPLE 1
  • The effect on the deposit characteristics of the following parameters were studied: (i) pH of bath, (ii) temperature of deposition, and (iii) rinsing immediately or after one day. Subsequent to deposition, impedance analysis and linear polarization were used to electrochemically characterize the final deposit. [0084]
  • The base silicate medium solution comprised 800 mL of distilled water+100 mL of PQ N Sodium Silicate solution (hereinafter referred to as 1:8 sodium: silicon solution). The PQ N Sodium Silicate solution is 8.9 wt % Na[0085] 2O and 28.7 wt % SiO2. The deposition was carried out in a plating cell made of glass on ACT zinc plated steel panels. Prior to deposition the panels were degreased with acetone and washed with demineralized water. Two different sets of parameters were varied in this experiment:
  • First, the effect of pH was studied at 75° C. at 10.5, 10.8, 11, 11.5 and 12. [0086]
  • Next, the effect of temperature was studied at 75° C., 80° C. and 85° C. [0087]
  • For both studies, the immersion time was held constant at 15 minutes. Subsequent to mineralization one set of panels was rinsed immediately. The second set of samples were rinsed after 24 hours before carrying out the measurements. [0088]
  • Next, the corrosion characteristics of the panel were studied in 0.5 M Na[0089] 2SO4 solution at pH 4. A representative panel area of 1 cm2 was chosen for testing. A three-electrode setup was used to study the corrosion behavior of the mineralized samples. The electrolyte used in this study is 0.5 M sodium sulfate, pH=4. Ti coated with Pd was used as the counter electrode. Hg/Hg2SO4 was used as the reference electrode. All potentials in this study are referred with respect to the Hg/Hg2SO4 electrode. Corrosion studies were done using Scribner Associates Corrware Software with EG&G Princeton applied Model 273 potentiostat/galvanostat and a Solartron 1255 frequency analyzer in accordance with conventional methods. The electrode was left on open circuit till the potential is stabilized. After the potential stabilized, non-destructive evaluation of the surface was done using linear polarization and impedance analysis. During linear polarization, the potential was varied 10 mV above and below the open circuit potential of the mineralized sample at a scan rate of 0.1667 mV/s. The impedance data generally covered a frequency range of 5 mHz to 10 kHz. A sinusoidal ac voltage signal varying by ±10 mV was applied. The electrode was stable during the experiments and its open circuit potential changed less than 1 mV.
  • In moderately alkaline solutions (pH <10.5) zinc forms passive films which reduce the rate of metal dissolution. Increasing the pH above 10.5 has a tendency to dissolve the passive film and active metal corrosion. FIG. 1 presents the open-circuit potential of galvanized zinc panels immersed in the base solution of pH 10.5. As seen from the plot, the potential initially increases from an initial value of around −0.49 V to more positive values. This indicates the formation of a passive film on the surface of zinc in presence of the base solution. [0090]
  • FIG. 2 shows the potential of galvanized steel in the base solution, pH=11 as a function of time. As shown in FIG. 2, the potential is more negative than that seen in FIG. 1 indicating formation of a relatively less stable film than the film formed at pH=10.5. However the observed potential of −0.7 V vs Hg/HgO reference electrode still indicates a passive film formation on Zn surface in presence of silicate solution even at pH=11. [0091]
  • Increasing the pH further to 11.5, can reduce the effectiveness of the inventive process (see FIG. 3). Note that the corrosion potential increases up to −1.38 V vs Hg/HgSO[0092] 4 reference electrode which is dissolution potential for Zn.
  • According to Pourbaix (Pourbaix, M.: Atlas of Electrochemical Equilibria in Aqueous Solutions, 2nd ed., National Association of Corrosion Engineers, Houston, pp. 406-413, 1974; hereby incorporated by reference), zinc exists in the various forms in solution, some of which are given below. The various equilibrium reactions between the dissolved substances are as follows: [0093] Zn 2 + + H 2 O = ZnOH + + H + ; log ( ZnOH + ) ( Zn 2 + ) = - 9.67 + pH ( 1 ) ZnOH + + H 2 O = HZnO 2 - + 2 H + ; log ( HZnO 2 - ) ( ZnOH + ) = - 17.97 + 2 pH ( 2 ) Zn 2 + + 2 H 2 O = HZnO 2 - + 3 H + ; log ( HZnO 2 - ) ( Zn 2 + ) = - 27.63 + 3 pH ( 3 ) HZnO 2 - = ZnO 2 - + H + ; log ( ZnO 2 - ) ( HZnO 2 - ) = - 13.11 + pH ( 4 )
    Figure US20040191536A1-20040930-M00001
  • With the increase in pH, the equilibrium is shifted to the right in all the above reactions. For reaction (2) and (3) the effect is more because of the greater dependence on H+concentration. Between pH 8.98 and 13.11 HZnO[0094] 2 dominates. Beyond this ZnO2 is present.
  • This Example illustrate that increasing beyond a certain level the pH decreases the chances for the formation of a passive film. [0095]
  • At pH 12 (FIG. 4) corrosion increases and the metal potential fluctuates significantly. Increasing the pH of the silicate medium beyond about 11 can cause active dissolution of the zinc leading to decreasing the protective zinc layer thickness. Increasing the temperature is seen to accelerate the rate of metal dissolution. Similar behavior is observed for pure Zn samples. [0096]
  • FIG. 5 and FIG. 6 summarizes the corrosion potentials determined on galvanized steel samples in base solution at 75° and 80° C., respectively. The corrosion potentials are shown as a function of time estimated in solutions with pH 10.5, 11, 11.5 and 12. The results indicated that at pH 10.5 at 75° C. and 80° C. passive film forms which is stable as a function of time. Note that increasing the temperature from 75 to 80° C, the potentials estimated at pH=10.5 and 11 shifts for approximately 200 mV in cathodic direction indicating a higher probability for a decrease of the coating barrier properties. [0097]
  • FIG. 7 shows the open circuit potential studies for Zn plated steel at different pHs (10.5, 11 and 12) in the absence of base solutions. As expected the relatively high corrosion potentials (higher than −1.0 V v. Hg/HgSO[0098] 4 reference electrode) were observed in the absence of silica in the solution indicating a high probability for Zn dissolution at pH 10.5 and higher
  • Tables 1 and 2 summarize the polarization resistance data of samples treated in accordance with the inventive mineralization process and tested at different temperatures and pH's (10.5, 10.8, 11, 11.5 and 12). Subsequent to mineralization one set of panels was rinsed immediately. The second set of samples was rinsed after 24 hours before carrying out the measurements. The rinsed panels data are presented in Table 1, while the data obtained from panels rinsed after 24 hours are presented in Table 2. In general the samples rinsed after 24 hours showed higher resistances. Increase in temperature from 75° C. to 80° C. leads to an increase in resistance. In contrast increasing the pH from 10.5 to 12 leads to a decrease in average resistance. [0099]
    TABLE 1
    No Current Data for temperatures 75, 80, and 85° C. - Rinse
    0.5 M Na2SO4
    pH 10.5 10.8 11 11.5 12
    75° C.
    Rp (Ω) 586 2060 712 584 410
    Rp (Ω) 697 1318 896 595 422
    Rp (Ω) 948 1429 686 183 404
    Rp (Ω) 840 1231 609 801 473
    Rp (Ω) 858 799 916 609
    Rp (Ω) 996 826 1441 931
    Average 821 1510 755 753 542
    80° C.
    Rp (Ω) 1072 1227 1219 849 731
    Rp (Ω) 963 892 1252 719 710
    Rp (Ω) 540 1346 1526 830 778
    Rp (Ω) 1319 2010 1301 624 905
    Rp (Ω) 2203 1079 975 1050
    Rp (Ω) 3342 1951 998 898
    Average 1573 1369 1388 833 845
    85° C.
    Rp (Ω) 249 1115 1887 783
    Rp (Ω) 519 1323 2080 1268
    Rp (Ω) 1078 1124 2133 1486
    Rp (Ω) 1429 926 1603 1225
    Rp (Ω) 1855
    Rp (Ω) 757
    Rp (Ω) 586
    Rp (Ω) 817
    Average 819 1063 1926 1191
  • [0100]
    TABLE 2
    No Current Data for temperatures 75, 80, and
    85° C. - RINSED AFTER 24 HOURS
    0.5 M Na2SO4
    pH 10.5 10.8 11 11.5 12
    75° C.
    Rp (Ω) 1136 1757 1000 712 766
    Rp (Ω) 846 1229 1295 727 592
    Rp (Ω) 1223 1649 1327 641 950
    Rp (Ω) 921 1423 983 1133 1044
    Rp (Ω) 1458 4092 1624 1483
    Rp (Ω) 3465 2509 2159 2106
    Average 1508 1515 1868 1166 1157
    80° C.
    Rp (Ω) 793 983 1715 2564 804
    Rp (Ω) 1490 989 1320 2809 931
    Rp (Ω) 1418 1094 1874 2792 563
    Rp (Ω) 1541 1085 1476 1973 509
    Rp (Ω) 3565 2236 7370 982
    Rp (Ω) 1545 12413 1265 4904
    Average 1725 1038 3506 3129 1449
    85° C.
    Rp (Ω) 785 729 941 1154
    Rp (Ω) 810 1050 883 1169
    Rp (Ω) 638 1457 992 1041
    Rp (Ω) 648 1577 7996 3769
    Rp (Ω) 1197
    Rp (Ω) 519
    Rp (Ω) 739
    Rp (Ω) 957
    Average 720 1028 2703 1783
  • EXAMPLE 2
  • A 1:8 (alkali to silica ratio) sodium silicate solution was prepared as described in Example 1. The effect of deposition time, the pH of the silicate medium and the temperature of the silicate medium were studied. Prior to deposition the panels were degreased with acetone and washed with demineralized water. The experiments were performed in duplicate. One set of panels was rinsed immediately following deposition and a second set was rinsed 24 hours later. The corrosion characteristics of the panels were tested in 0.5 M Na[0101] 2SO4 solution at pH 4. A representative panel area of 1 cm2 was tested. The rest of the panel was masked with an insulating tape. A three-electrode setup was used to study the corrosion behavior of the mineralized samples. Titanium coated with palladium was used as the counter electrode and Hg/Hg2Cl2 was used as the reference electrode. All potentials are with respect to the Saturated Calomel electrode. Corrosion studies were done using a Scribner Associates Corrware Software with EG&G Princeton Applied Research Model 273 potentiostat/galvanostat and a Solartron 1255 frequency analyzer in accordance with conventional procedures. The electrode was left on open circuit until the potential stabilized. Non-destructive evaluation of the surface was done using linear polarization and impedance analysis. During linear polarization, the potential was varied 10 mV above and below the open circuit potential of the mineralized sample at a scan rate of 0.1667 mV/s. The impedance data generally covered a frequency range of 5 mHz to 10 kHz. A sinusoidal AC voltage signal varying by ±10 mV was applied. The electrode was stable during the experiments and its open circuit potential changed less than 1 mV. Separately, samples were prepared for scanning electron microscopy (SEM) and EDAX analysis that were obtained by using a Hitachi S-2500 Delta SEM.
  • Table 3 presents corrosion resistance data for electroless plated prepared at different bath temperatures. In general, increasing the temperature from 25° C. to 75° C. leads to an increase in resistance. However, increasing the temperature further to 85° C. results in decrease in resistance. For these samples, 75° C. is a desirable bath temperature for electroless mineralization. [0102]
    TABLE 3
    Comparison of corrosion resistance for samples
    mineralized at different bath temperatures.
    Resistance (Ω-cm2) in pH 4, 0.5 M Na2SO4
    75° C. 85° C.
    25° C. 24 24
    Temperature Immediate 24 Hour Immediate Hour Immediate Hour
    Location Rinse Rinse Rinse Rinse Rinse Rinse
    1 301 216 586 1136 249 718
    2 225 321 697 846 519 835
    3 265 345 948 1223 1078 638
    4 400 425 840 921 1429 648
    5 350 500 858 1458 819 720
    6 215 322 996 3465 534 810
    Avg. 292.7 354.8 821 1508 771.3 728.2
    High 400 500 996 3465 1429 835
    Low 215 216 586 846 519 638
  • Table 4 presents corrosion resistance data for electroless plated samples prepared at pH 10.5 and 11. Increasing the pH from 10.5 to 11 leads to an increase in average resistance. Samples that are rinsed after 24 hours typically exhibit better corrosion resistance than samples rinsed immediately. The same trend is observed for the samples prepared at different temperatures. FIG. 8 shows a comparison of the SEM and EDAX analysis of samples rinsed immediately and rinsed after 24 hours. Samples rinsed immediately have no detectable Si on the surface whereas samples rinsed after 24 hours show 12% Si on the surface. This corresponds to the increased resistance shown in Tables 3 and 4. [0103]
    TABLE 4
    Comparison of corrosion resistance for samples mineralized
    at different pH in 1:8 sodium silicate at 75° C.
    Resistance (Ω-cm2) in pH 4, 0.5 M Na2SO4
    pH
    10.5 11
    Immediate 24 Hour Immediate 24 Hour
    Location Rinse Rinse Rinse Rinse
    1 586 1136 712 1000
    2 697 846 896 1295
    3 948 1223 686 1327
    4 840 921 609 983
    5 858 1458 799 4092
    6 996 3465 826 2509
    Avg. 821 1508 755 1868
    High 996 3465 896 4092
    Low 586 846 609 983
  • Table 5 presents compares the corrosion resistance of samples with different deposition times. In general, the resistance ranges from 1400-1700 W-cm2. [0104]
    TABLE 5
    Corrosion resistance for samples mineralized in 1:8
    sodium silicate at 75° C. at different deposition times.
    Resistance (Ω-cm2) in pH 4, 0.5 M Na2SO4
    Location 5 minutes 10 minutes 15 minutes 20 minutes
    1 2500 1885 2412 759
    2 754 684 867 2295
    3 913 2286 1686 1959
    Avg. 1389 1618.3 1655 1668
    High 2500 2286 2412 2295
    Low 754 684 867 759
  • In view of the above data presented in Example 1 and 2, one of skilled in the art should understand and appreciate that the mineralization bath should be heated, typically to a temperature of about 70 to 80 C. One should also note that in general, rinsing the [0105] samples 24 hours after mineralization results in increased resistance measurements and higher silicon content than samples immediately rinsed after treatment. Finally it should be noted by a skilled artisan, that the corrosion resistance of the sample verse time is optimized after approximately 15 minutes of treatment in the mineralization bath. The temperature of the bath, silicate concentration and drying regime can be employed for optimizing the corrosion resistance of the treated metal surface.
  • EXAMPLE 3
  • As shown above, samples that are rinsed after 24 hours can show increased resistance compared to samples that are rinsed immediately, suggesting that the silicate dries and crystallizes on the surface. The present example demonstrates (i) the effect of post-mineralization heating and (ii) the effect of the concentration of the silicate bath. [0106]
  • A first set of samples were mineralized in a 1:8 (alkali:silica ratio) silicate solution for 15 minutes and dried at 100° C. for one hour immediately. A second set was mineralized and left to dry at room temperature for 24 hours. Table 6 shows corrosion resistance for the samples. Heating results in a dramatic increase in corrosion resistance, but the resistance may not be uniform across the samples, indicating non-uniformity of Si on the surface. [0107]
    TABLE 6
    Comparison of resistance for samples mineralized in
    1:8 sodium silicate with and without post-deposition heating.
    Resistance (Ω-cm2) in pH 4, 0.5 M Na2SO4
    Location No Heating Heating at 100° C. for 1 hour
    1 2412 4.4 × 104
    2 867 4.7 × 104
    3 1686 725.2
    Avg. 1655 3.1 × 104
    High 2412 4.7 × 104
    Low 867 725.2
  • Table 7 shows the corrosion resistance of samples mineralized as above and heated at different temperatures for one hour. Increasing the drying temperature typically increases the average resistance. [0108]
    TABLE 7
    Comparison of resistance for samples mineralized in 1:8
    sodium silicate and heated at different post-deposition
    temperatures. Resistance (Ω-cm2) in pH 4, 0.5 M
    Na2SO4.
    Location 100° C. 125° C. 150° C. 175° C. 200° C.
    1 4.4 × 104 702.9 8.2 × 104 1.2 × 105 2.1 × 105
    2 4.7 × 104 6.8 × 104 8.4 × 104 1600 780.7
    3 725.2 4.0 × 104 1644.3 8.2 × 104 2.3 × 104
    Avg. 3.1 × 104 3.5 × 104 5.6 × 104 6.8 × 104 7.8 × 104
    High 4.7 × 104 6.8 × 104 8.4 × 104 1.2 × 105 2.1 × 105
    Low 725.2 702.9 1644.3 1600 780.7
  • The samples of Table 8 were placed under water for seven days, and the corrosion resistance determined periodically. As shown in Table 8, the resistance drops to less than 1000 Ω-cm[0109] 2 for all the samples after seven days. Without wishing to be bound by any theory of explanation it is believed that water can penetrate through microcracks in the 10 coating and attacks the underlying layer. The dissolution of Zn can lead to the removal of the protective coating and eventually causes the corrosion rate to increase.
    TABLE 8
    Comparison of resistance after 1 week immersed in water
    for surfaces mineralized in 1:8 sodium silicate. Resistance
    (Ω-cm2) in pH 4, 0.5 M Na2SO4.
    No. of days 100° C. 125° C. 150° C. 175° C. 200° C.
    Initial 3.1 × 104 3.6 × 104 6.0 × 104 6.5 × 104 8.1 × 104
    1 day 822.8 844.1 1240.5  1521.6  1623.5
    4 days 580.1 612.5 800.2 911.3 954
    7 days 400.1 512.3 564.7 603.1 625.4
  • Table 9 presents corrosion resistance data for samples mineralized in different concentrations of silicate solution. In this example, a series of bath solutions having differing ratios of PQ solution to water were prepared. For example, a 1:1 solution was prepared by adding 1 part PQ solution to 1 part water. Following mineralization, the samples were heated at 100° C. for 1 hour. Data representative of the results achieved are given below. One of skill in the art should understand and appreciate that the corrosion resistance generally increases with bath concentration. With the 1:8 and the 1:4 baths, the corrosion resistance appears to be variable across the surface. However, with the 1:3 ratio bath and higher ratio baths, resistances in the range of 10[0110] 5 Ω-cm2 are measured across the surface. Thus one of skill in the art should conclude that the 1:3 is a desirable bath concentration for these samples.
    TABLE 9
    Comparison of resistance for surfaces mineralized in
    different concentrations of sodium silicate solution.
    Resistance (Ω-cm2) in pH 4, 0.5 M Na2SO4
    Location 1:8 1:4 1:3 1:2 1:1
    1 4.4 × 104 8200 3.3 × 105 7.7 × 105 2.2 × 106
    2 4.7 × 104 1.7 × 105 1.8 × 105 1.2 × 106 1.8 × 106
    3 725.2 3.0 × 105 4.9 × 105 1.3 × 106 1.9 × 106
    Avg. 3.1 × 104 6.9 × 104 3.3 × 105 1.1 × 106 2.0 × 106
    High 4.7 × 104 3.0 × 105 4.9 × 105 1.3 × 106 2.2 × 106
    Low 725.2 8200 1.8 × 105 7.7 × 105 1.8 × 106
  • Samples mineralized in 1:3 sodium silicate were heated at different temperatures for 1 hour and kept under water for seven days. As shown in Table 10, the resistances measured immediately after drying, indicate that increasing drying temperature tends to increase the average resistance of the samples. However, the resistances of all the samples can drop to under 1000 W-cm2 after seven days immersed in water. [0111]
    TABLE 10
    Comparison of resistance after 1 week immersed in water
    for surfaces mineralized in 1:3 sodium silicate and heated
    at various temperatures for 1 hour. Resistance (Ω-cm2)
    in pH 4, 0.5 M Na2SO4.
    Location Room temp. 100° C. 125° C. 150° C. 175° C. 200° C.
    1 2246 3.3 × 105 7.1 × 105 7.2 × 105 3.2 × 105 8.0 × 105
    2 1879 1.8 × 105 6.8 × 105 8.4 × 105 1.2 × 106 1.5 × 106
    3 2224 4.9 × 105 1.4 × 105 4.8 × 105 9.2 × 105 1.0 × 106
    Avg. 2116.2 3.3 × 105 5.1 × 105 6.8 × 105 8.1 × 105 1.1 × 106
    High 2246 4.9 × 105 7.8 × 105 8.4 × 105 1.2 × 106 1.5 × 106
    Low 1879 1.8 × 105 1.4 × 105 4.8 × 105 3.2 × 105 8.0 × 105
  • [0112]
    TABLE 11
    Comparison of resistance after immersion in water
    for surfaces mineralized in 1:3 sodium silicate and
    heated at various temperatures for 1 hour. Resistance
    (Ω-cm2) in pH 4, 0.5 M Na2SO4.
    Days Room temp. 100° C. 125° C. 150° C. 175° C. 200° C.
    Initial 2116.2 3.5 × 105 5.0 × 105 6.8 × 105 8.4 × 105 1.3 × 106
    1 632.1 2247.8 2509 2496.2 3561.3 3626
    4 601.1 1028.2 978 856.3 1211.3 1490.4
    7 580 532.1 612.3 632.6 657.7 691.9
  • The dried samples can be rinsed to remove any water soluble species. If desired, the rinse solution can comprise at least one composition for further modifying the dried sample (e.g., silanes, colloidal silica, among other materials). [0113]
  • EXAMPLE 4
  • Hydrogen is evolved at the surface of the cathode during electroplating and the rate of hydrogen evolution can be controlled by varying the applied potential or current. Hydrogen production also releases hydroxyl groups into the solution thereby increasing pH. However, in the case of electroless deposition, this can be accomplished through the use of selected reducing agents. [0114]
  • FIG. 9 presents the Si concentration of samples mineralized in 1500 mL of 1:3 sodium silicate in the presence of increasing amounts of sodium borohydride. Comparison of the samples dried in air with the samples heated at 175 C is shown. With samples dried in air, the Si content increases with borohydride concentration. With the heated samples, the Si content initially decreases with borohydride concentration, but no decrease is observed at borohydride concentrations greater than 5 g. [0115]
  • The stability of the coatings prepared without post-deposition heating is shown in Table 12 note as shown above post-deposition heating improves corrosion resistance). The stability of the coatings is improved by the addition of sodium borohydride. The corrosion resistance of the coatings prepared with 10 g of sodium borohydride drops from 1941.5 W-cm2 to 1372.1 W-cm2 after seven days, whereas the resistance of coating prepared in the absence of sodium borohydride drops from 2116.2 W-cm2 to 580 W-cm2. FIG. 10 shows a plot of this data. [0116]
    TABLE 12
    Comparison of resistance after immersion in water
    for surfaces mineralized in 1500 mL of 1:3 sodium
    silicate in the presence of various amounts of sodium
    borohydride. Resistance (Ω-cm2) in
    pH 4, 0.5 M Na2SO4.
    Days
    immersion No NaBH 4 5 g NaBH 4 10 g NaBH 4 15 g NaBH4
    Initial 2116.2 1870.1 1941.5 2168.9
    1 632.1 1650.7 1660.2 2071.7
    4 601.1 1072.1 1491.8 1856.2
    7 580 830.1 1372.1 1590.1
  • A similar trend is observed with samples subjected to post-mineralization heating at 175° C. for one hour. The average resistance of the coating prepared using 10 g of sodium borohydride drops to 1488.6 W-cm2 after seven days, compared to 570.7 W-cm2 observed after seven days for the coating prepared in the absence of sodium borohydride (Table 13). A plot of this data is shown in FIG. 11. [0117]
    TABLE 13
    Comparison of resistance after immersion in water
    for surfaces mineralized in 1500 mL of 1:3 sodium
    silicate in the presence of various amounts of sodium
    borohydride and heated at 175° C. for one hour.
    Resistance (Ω-cm2) in pH 4, 0.5 M Na2SO4
    Days
    immersion No NaBH 4 5 g NaBH 4 10 g NaBH 4 15 g NaBH4
    Initial 3.3 × 105 4.1 × 104 1.9 × 104 3456
    1 1690.4  1488.6 2677.8 2131.2
    4 983.1 1132.4 1939.0 1446.7
    7 570.7  916.1 1488.6 1243.1
  • Surfaces mineralized in 1500 mL of 1:3 sodium silicate in the presence of different amounts of sodium borohydride were used as working electrodes for cyclic voltammetry in a three electrode cell, using a calomel reference electrode and a scan rate of 5 mV/s. One set of surfaces was dried in air for 24 hours, while a second set was heated at 175° C. for one hour. FIG. 12 shows voltamograms for the air dried samples. The observed current corresponds to corrosion of the surface layer. At a bare galvanized surface, increasing the potential more positive than −1.1 V leads to stripping Zn from the surface. In the reverse scan, deposition is observed as mass transfer limited current. [0118]
  • For the SiO[0119] 2-coated surfaces, peak reduction current and maximum oxidation current can decrease rapidly. Since the currents are dependent of the amount of material lost from the surface, the inhibiting efficiency of the silica on Zn can be estimated from the voltammograms as:
  • Inhibiting efficiency (%)=[(Peak Current Coated)/(Peak Current Bare)]×100
  • FIG. 13 shows a plot of the inhibiting efficiencies from the voltammogram of FIG. 12. The inhibiting efficiency typically increases with increasing sodium borohydride concentration. [0120]
  • Voltammograms of the surfaces coated in the presence of sodium borohydride and heated at 175° C. for one hour are shown in FIG. 14. Currents in the SiO[0121] 2-coated samples are negligible compared to the bare surface. The inhibiting efficiency is shown in FIG. 15.
  • Cyclic voltammetry (CV) was performed with surfaces with and without post-mineralization heating after immersing them in water for one week. FIG. 16 shows the CVs of the samples prepared in the presence of different amounts of sodium borohydride and air-dried for 24 hours. The current increases to the order of 1 mA after one week. FIG. 17 shows the decrease in the inhibiting efficiency after one week immersion in water. Similar results are observed for the surfaces subjected to post-deposition heating at 175° C. for one hour (FIGS. 18 and 19). The change in inhibiting efficiency is the lowest for samples prepared with 10 g of sodium borohydride. [0122]
  • FIG. 20 shows SEM images of surfaces prepared in the presence of 10 g of sodium borohydride before and after immersion in water. Upon inspection one of skill in the art should notice that a 2 μm crack is observed. It will be appreciated by such a skilled artisan that such cracks facilitate the entry of water through the coating and allow attack of the underlying surface. As the cracks become large, to the order of 8-10 mm and flakes of zinc appear on the surface. EDAX on surfaces coated in the presence of different amounts of sodium borohydride and left to dry in air for 24 hours indicates that the Si content drops for all the samples, but the drop is the least for the sample prepared in the presence of 10 g of sodium borohydride (FIG. 21). Similar behavior is observed for surfaces prepared with post-deposition heating (FIG. 22). [0123]
  • These studies indicate to one of skill in the art that surfaces coated via electroless mineralization in the presence of sodium borohydride. [0124]
  • EXAMPLE 5
  • The following table shows examples of the inventive process that employs a heated silicate medium for treating standard M-10 bolts. The heated silicate medium comprised 10% N-Grade PQ sodium silicate solution (which comprises 2.88% SiO2, 0.90% alkali) and silica colloids that ranged in size from about 10 nm to about 1,000 nanometers (and typically 1 to 100 nm). [0125]
    STANDARD M-10 BOLT RUN
    PARAMETER SUMMARIES
    Bath Number Of Total Bolt D.C. D.C.
    Run # Time (Min) Temp (C) CD (ASI) A:C Area Bolts Area (sq. ln) Current (A) Potential (V) Results
    1 15 74.3-75.8 0.055 1-1.9 100 500 28 10.7-15.0 Bright & Silvery
    Appearance
    2 0 N/A 0 0 100 500 0 0 Eclipse Zinc
    Plate Control
    3 0 N/A 0 0 100 500 0 0 Eclipse Zinc
    Plate Control
    4 15 74.6-75.5 0.055 1:1.9 100 500 27.5 10.9-12.3 Bright & Silvery
    Appearance
    5 15 71.3-74.5 0 0 100 500 0 0 Hot Soak
    6 15 72.8-75.1 0 0 100 500 0 0 Hot Soak
    7 0 N/A 0 0 100 500 0 0 Eclipse Zinc
    Supplied by
    Atotech ®
    8 0 N/A 0 0 100 500 0 0 Eclipse Zinc
    Supplied by
    Atotech ®
    9 15 36.3-37.1 0 0 68 340 0 0 Cold Soak
    10 15 74.5-75.6 0 0 22 110 0 0 Hot Soak
    1 0 N/A 0 0 6 30 0 0 Zinc Plate
    Control
    2 15 26.6 0 0 23 115 0 0 Cold Soak
    3 15 74.3-75.6 0 0 24 120 0 0 Hot Soak
    4 2.5 73.1-74.9 0.1 1:1   53 265 27 <24.7 Bright & Silvery
    Appearance
    5 15 24.6 0 0 9 45 0 0 Cold Soak/New
    Solution
    6 15 73-75 0 0 9 45 0 0 Hot Soak/New
    Solution
    7 15 74.5-75.2 0 0 6 30 0 0 Hot Soak
  • [0126]
    POST-TREATMENT/TOPCOATS
    Group
    #  Run# Post-Treat. Top-Coat A Process
     1A
    2 Dry Only None
     1B
    3 Dry Only None
     2 3 Dry Only Magni ®
    B17
     3 2 Dry Only Magni ®
    B18
     4A 5 A Process None
     4B 6 A Process None 1. 90 Sec. Spin
    Dry
     5 6 A Process Magni ® 2. 10 sec. De-Ionized
    B17 Water Rinse
     6 5 A Process Magni ® 3. 60 Sec. Spin
    B18 Dry
     7A 1 A Process None 4. 10 Sec. A1 Silane
    Rinse
     7B 4 A Process None 5. 60 Sec. Spin
    Dry
     8 4 A Process Magni 6. 10 Sec. A2 Silane
    B ®17 Rinse
     9 1 A Process Magni ® 7. 90 Sec. Spin
    B18 Dry
    10 7/8 Corrosil None
    11 7/8 Corrosil Magni ® Corrosil & Ecotri
    B17 Treatments
    12 7/8 Corrosil Magni ® Applied By
    B18 Atotech
    13 7/8 Ecotri None
    14 7/8 Ecotri Magni ® Topcoats ˜0.2 mil
    B17 thickness
    15 7/8 Ecotri Magni ®
    B18
    16 9 Dry Only None
    17 9 A Process None
    18 9 A Process Magni ®
    B17
    19 9 A Process Magni
    B ®18
    20 10  A Process None
     1 1 Dry Only None
     2 2 Dry, Rinse, Dry None
     3 3 Dry, Rinse, Dry None
     4 4 Dry, Rinse, Dry None
     5 5 Immediate Rinse None New Solution:
     6 5 Dry, Rinse, Dry None New Solution:
     7 6 Immediate Rinse None New Solution:
     8 6 Dry, Rinse, Dry None New Solution:
     9 7 Spin Dry Only None Ripened
    Solution
    10 6 Spin Dry Only None New Solution:
  • Upon review of the above representative data and information, one of skill in the art should understand and appreciate that the process of the present invention can be carried out in a routine manner on industrial parts and workpieces using standard metal finishing equipment. It should also be appreciated that the mineralized samples can be further treated with a top coat or other additional protective coating to aid in the handling and transport of the mineralized parts or workpieces. [0127]
  • EXAMPLE 6
  • The present example illustrates the effect of post-treatment heating of the samples. The edge of a 2.75 inch diameter×6 inch long electric motor laminate core assembly comprising individual laminates (high silicon steel alloy) mechanically coined together and assembled onto a simulated shaft was treated. These laminates can be used from constructing the rotor of an electric motor. Mineralization was carried out in a 1:3 ratio bath made of 1 part sodium silicate (PQ) solution and 3 parts water. The temperature of the bath was maintained at 75 C and a deposition time of 15 minutes. Post treatment heating of the samples was carried out at 25 C until the sample was dry and 175 C until the sample was dry. [0128]
  • Data representative of the corrosion resistance (Ω-cm[0129] 2) in pH 4, 0.5 M Na2SO4 Solution of the samples mineralized in a 1:3 PQ Bath at pH 10.5 for 15 minutes is given below
    Location 25 C dry 120 C dry
    1 1087.8 38146
    2 2222.1 61923
    3 1600 48083
    Average Value 1636.6 49384
  • Data representative of the corrosion resistance (Ω-cm2) in [0130] pH 4, 0.5 M Na2SO4 Solution of the samples mineralized in Mineralize in 1:3 PQ Bath with NaBH4 (10 g/l), at pH 10.5 for 15 minutes is given below
    Location 25 C dry 120 C dry
    1 6883.2 26961
    2 15108 27049
    3 7711.4 24858
    Average Value 9900.9 26289
  • EDAX analysis of the samples dried at 25 C and prepared in the NaBH[0131] 4 containing bath is compared to the samples prepared without the NaBH4 gave the following exemplary data:
    NaBH4 Bath Control (no NaBH4)
    Atomic %
    Oxygen 0.000 0.000
    Silicon 55.187 42.329
    Iron 44..813 57.671
    Conc. (Wt %)
    Oxygen 0.00 0.000
    Silicon 38.247 26.960
    Iron 61.753 73.040
  • Upon review of the above exemplary data, one of skill in the art should understand and appreciate that the inclusion of NaBH[0132] 4 into the mineralization bath substantially increases the mineralized protective layer formed.
  • Examples 7-9 illustrate silicate media containing complexing agents and dopants. These silicate media were prepared in laboratory scale equipment. [0133]
  • EXAMPLE 7
  • 20 gms of sodium citrate dihydrate (complexing agent), 1 gm Nickel chloride (dopant), 1 gm Molybdenum (dopant), and 1 gm cobalt chloride (dopant) were dissolved in 500 ml of water to prepare a first solution. Then and 0.5 gm of MgO and 1 gm aluminum dissolved in 1:3 sodium silicate solution (supplied by PQ) which when added to the 500 ml water makes up 1:3 bath to prepare a second solution. The first and second solutions were combined. The combined solution had a violet hue and pH of about 11.5. [0134]
  • EXAMPLE 8
  • 20 gms of sodium citrate dihydrate, 1 gm nickel chloride, 1 gm cobalt chloride, and 0.5 gm molybdenum were dissolved in 500 ml of water in order to prepare a first solution. Then a second solution of 1:3 sodium silicate was prepared. The first and second solutions were combined. The combined solutions had a violet hue and pH of about 11.0. [0135]
  • EXAMPLE 9
  • 20 gms of Sodium citrate dihydrate, 1 gm Nickel chloride, 0.5 gm Molybdenum, and 1 gm cobalt chloride were dissolved in 500 ml of water in order to prepare a first solution. A second solution comprising 1:3 sodium silicate was prepared. The first and second solutions were combined. [0136]
  • If desired a reducing agent solution comprising sodium borohydride (e.g., 4 grams of sodium borohydride dissolved in 50 ml water) can be added to solutions of Examples 7-9. [0137]
  • While the apparatus, compositions and methods of this invention have been described in terms of preferred or illustrative embodiments, it will be apparent to those of skill in the art that variations may be applied to the process described herein without departing from the concept and scope of the invention. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the scope and concept of the invention. [0138]

Claims (19)

1. An electroless method for treating a substrate having an electrically conductive surface comprising:
contacting at least a portion of the surface with a medium comprising water, about 1 to about 15 weight percent of at least one silicate and having a basic pH and wherein said medium has a temperature of greater than about 50 C; and,
drying the substrate.
2. The method of claim 1 wherein the medium further comprises colloidal silica, and wherein the medium is substantially free of chromates and VOCs.
3. An electroless method for treating a metallic or an electrically conductive surface comprising:
exposing at least a portion of the surface to a medium comprising a combination comprising water, colloidal silica, and at least one water soluble silicate wherein said medium has a basic pH,
drying the surface, ; and
contacting the treated surface with at least one composition that adheres to the treated surface.
4. The method of claim 3 wherein the colloidal silica has a particle size of less than about 50 nanometers.
5. The method of claim 1 wherein the surface comprises at least one member selected from the group consisting of copper, nickel, tin, iron, zinc, aluminum, magnesium, stainless steel and steel and alloys thereof.
6. The method of claim 1 further comprising rinsing after said drying and said rinsing comprises contacting the surface with a second medium comprising a combination comprising water and at least one water soluble compound selected from the group consisting of carbonates, chlorides, fluorides, nitrates, zironates, titanates, sulphates, water soluble lithium compounds and silanes.
7. The method of claim 1 wherein the medium comprises at least one dopant selected from the group consisting of zinc, cobalt, molybdenum, nickel, and aluminum.
8. The method of claim 1 wherein said drying is conducted at a temperature of at least about 120 C.
9. The method of claim 5 wherein said surface comprises zinc or zinc alloys.
10. The method of claim 7 wherein the medium comprises a combination comprising water, greater than about 1 weight percent of sodium silicate and at least one dopant selected from the group consisting of cobalt, nickel and molybdenum.
11. The method of claim 1 wherein the surface comprises a chromated surface.
12. The method of claim 3 wherein said medium further comprises at least one water dispersible polymer.
13. The method of claim 1 wherein said method further comprises contacting with at least one acid.
14. The method of claim 9 wherein said surface comprises zinc nickel alloys.
15. The method of claim 1 wherein the pH of the medium ranges from about 10 to about 12.
16. The method of claim 9 wherein the surface comprises die cast zinc.
17. The method of claim 1 wherein said medium further comprises at least one reducing agent selected from the group consisting of sodium borohydride and hypophosphide.
18. The method of claim 1 further comprising applying at least one coating selected from the group consisting of latex, silanes, epoxies, silicone, amines, alkyds, urethanes, polyester and acrylics.
19. The method of claim 1 wherein said at least one silicate comprises at least one alkali silicate having an alkali to silica ratio of about 1:3.
US10/820,692 2001-08-03 2004-04-08 Electroless process for treating metallic surfaces and products formed thereby Abandoned US20040191536A1 (en)

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Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050133651A1 (en) * 2003-10-31 2005-06-23 Chung Cheung Fishing reel gear mechanism coating
WO2008010824A2 (en) * 2005-09-13 2008-01-24 University Of South Carolina Improved catalysts for fuel cell applications using electroless deposition
US20090056991A1 (en) * 2007-08-31 2009-03-05 Kuhr Werner G Methods of Treating a Surface to Promote Binding of Molecule(s) of Interest, Coatings and Devices Formed Therefrom
US20090117257A1 (en) * 2005-09-13 2009-05-07 University Of South Carolina Catalysts for Fuel Cell Applications Using Electroless Deposition
US20090225585A1 (en) * 2007-12-27 2009-09-10 Hawkins J Adrian Self-Contained Charge Storage Molecules for Use in Molecular Capacitors
WO2009117379A1 (en) * 2008-03-18 2009-09-24 Metal Coating Technologies, Llc Protective coatings for metals
US20100006794A1 (en) * 2008-07-14 2010-01-14 Hawkins J Adrian Phosphonium Ionic Liquids, Compositions, Methods of Making and Devices Formed There From
US20100071938A1 (en) * 2007-08-31 2010-03-25 Kuhr Werner G Methods of treating a surface to promote metal plating and devices formed
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US8907133B2 (en) 2008-07-14 2014-12-09 Esionic Es, Inc. Electrolyte compositions and electrochemical double layer capacitors formed there from
US8927775B2 (en) 2008-07-14 2015-01-06 Esionic Es, Inc. Phosphonium ionic liquids, salts, compositions, methods of making and devices formed there from
US9345149B2 (en) 2010-07-06 2016-05-17 Esionic Corp. Methods of treating copper surfaces for enhancing adhesion to organic substrates for use in printed circuit boards
US9435036B2 (en) * 2014-09-08 2016-09-06 Mct Holdings Ltd Silicate coatings

Families Citing this family (38)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6455100B1 (en) 1999-04-13 2002-09-24 Elisha Technologies Co Llc Coating compositions for electronic components and other metal surfaces, and methods for making and using the compositions
WO2003035942A2 (en) * 2001-08-03 2003-05-01 Elisha Holding Llc An electrolytic and electroless process for treating metallic surfaces and products formed thereby
JP2005511887A (en) * 2001-08-03 2005-04-28 エリシャ・ホールディング・エルエルシー Electroless process for treating metal surfaces and products produced thereby
CN1692178A (en) * 2002-02-05 2005-11-02 以利沙控股有限公司 Method for treating metallic surfaces and products formed thereby
US20040188262A1 (en) * 2002-02-05 2004-09-30 Heimann Robert L. Method for treating metallic surfaces and products formed thereby
JP4151301B2 (en) * 2002-04-19 2008-09-17 スズキ株式会社 Surface treatment method and treatment liquid for aluminum or aluminum alloy
DE10223022A1 (en) * 2002-05-22 2003-12-11 Christoph Schulz Conversion layer for substrates made of zinc or alloys containing zinc
US20040126483A1 (en) * 2002-09-23 2004-07-01 Heimann Robert L. Coating compositions for electronic components and other metal surfaces, and methods for making and using the compositions
AU2002953190A0 (en) * 2002-12-09 2002-12-19 Commonwealth Scientific And Industrial Research Organisation Aqueous coating solutions and method for the treatment of a metal surface
US7950221B2 (en) * 2003-04-25 2011-05-31 Catelectric Corp. Methods and apparatus for controlling catalytic processes, including catalyst regeneration and soot elimination
DE10330192B4 (en) * 2003-07-03 2008-11-13 Infineon Technologies Ag A method of depositing a porous primer layer on a surface of an electrically conductive body and use of the method
US20050031894A1 (en) * 2003-08-06 2005-02-10 Klaus-Peter Klos Multilayer coated corrosion resistant article and method of production thereof
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JP2005320559A (en) * 2004-05-06 2005-11-17 Nippon Steel & Sumikin Stainless Steel Corp Automobile exhaust system component having excellent initial rust resistance
NL1027015C2 (en) * 2004-09-10 2006-03-13 Modina B V Method for preparing a silicate-based foam, device for applying it, spray can, and foam product obtained according to the method.
US20060247714A1 (en) * 2005-04-28 2006-11-02 Taylor William J Glass-to-metal feedthrough seals having improved durability particularly under AC or DC bias
WO2008073887A2 (en) * 2006-12-11 2008-06-19 Elisha Holding, Llc Method for treating metallic surfaces with an alternating electrical current
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MX2016017241A (en) * 2014-06-27 2017-04-25 Henkel Ag & Co Kgaa Dry lubricant for zinc coated steel.
US10321569B1 (en) 2015-04-29 2019-06-11 Vpt, Inc. Electronic module and method of making same
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Citations (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2462763A (en) * 1937-03-20 1949-02-22 Met Proprietary Ltd Di Protectively coated ferrous metal surfaces and method of producing same
US3977888A (en) * 1969-12-08 1976-08-31 Kansai Paint Company, Ltd. Inorganic coating compositions with alkali silicate
US4259409A (en) * 1980-03-06 1981-03-31 Ses, Incorporated Electroless plating process for glass or ceramic bodies and product
US4466832A (en) * 1981-11-06 1984-08-21 Daikin Kogyo Company, Limited Composition for forming hydrophilic coating
US5068134A (en) * 1988-06-20 1991-11-26 Zaclon Corporation Method of protecting galvanized steel from corrosion
US5108793A (en) * 1990-12-24 1992-04-28 Armco Steel Company, L.P. Steel sheet with enhanced corrosion resistance having a silane treated silicate coating
US5266412A (en) * 1991-07-15 1993-11-30 Technology Applications Group, Inc. Coated magnesium alloys
US5326594A (en) * 1992-12-02 1994-07-05 Armco Inc. Metal pretreated with an inorganic/organic composite coating with enhanced paint adhesion
US5433976A (en) * 1994-03-07 1995-07-18 Armco, Inc. Metal pretreated with an aqueous solution containing a dissolved inorganic silicate or aluminate, an organofuctional silane and a non-functional silane for enhanced corrosion resistance
US5451431A (en) * 1993-11-16 1995-09-19 Betz Laboratories, Inc. Composition and process for treating metal surfaces
US5487919A (en) * 1990-04-09 1996-01-30 Kawasaki Steel Corporation Method of manufacturing of galvanized steel sheet having high press formability
US5700523A (en) * 1996-06-03 1997-12-23 Bulk Chemicals, Inc. Method for treating metal surfaces using a silicate solution and a silane solution
US5759629A (en) * 1996-11-05 1998-06-02 University Of Cincinnati Method of preventing corrosion of metal sheet using vinyl silanes
US6033495A (en) * 1997-01-31 2000-03-07 Elisha Technologies Co Llc Aqueous gel compositions and use thereof
US6761934B2 (en) * 2001-08-03 2004-07-13 Elisha Holding Llc Electroless process for treating metallic surfaces and products formed thereby

Family Cites Families (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3340161A (en) * 1964-02-19 1967-09-05 Sperry Rand Corp Printed circuits and method of manufacture thereof
JPS5182325A (en) * 1975-01-17 1976-07-19 Nippon Steel Corp AENNOFUSHOKUYOKUSEIHOHO
JPS545835A (en) * 1977-06-15 1979-01-17 Nippon Steel Corp Method of treating metal surface
US4624898A (en) * 1984-08-07 1986-11-25 Harborchem, Inc. Processes for the application of refractory compositions to surfaces such as for the preparation of refractory shell molds and refractory compositions produced thereby
US4908075A (en) * 1986-08-28 1990-03-13 Nippon Paint Company, Ltd. Surface treatment chemical for forming a hydrophilic coating
JPH0813348B2 (en) * 1988-11-08 1996-02-14 シチズン時計株式会社 Metal surface layer of accessories such as watch cases and method of forming the same
JP2950481B2 (en) * 1990-11-29 1999-09-20 株式会社日本ダクロシャムロック Metal surface treatment method
US5455080A (en) * 1992-08-26 1995-10-03 Armco Inc. Metal substrate with enhanced corrosion resistance and improved paint adhesion
US6143420A (en) * 1994-10-21 2000-11-07 Elisha Technologies Co Llc Corrosion resistant coatings containing an amorphous phase
US5714093A (en) * 1994-10-21 1998-02-03 Elisha Technologies Co. L.L.C. Corrosion resistant buffer system for metal products
US6153080A (en) * 1997-01-31 2000-11-28 Elisha Technologies Co Llc Electrolytic process for forming a mineral
JPH10277476A (en) * 1997-04-10 1998-10-20 Kobe Steel Ltd Surface treated metallic plate excellent in soil resistance and its production
US6174609B1 (en) * 1997-12-19 2001-01-16 Shin-Etsu Chemical Co., Ltd. Rare earth-based permanent magnet of high corrosion resistance
JPH11335864A (en) * 1998-05-20 1999-12-07 Nkk Corp Production of surface treated steel plate having excellent corrosion resistance

Patent Citations (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2462763A (en) * 1937-03-20 1949-02-22 Met Proprietary Ltd Di Protectively coated ferrous metal surfaces and method of producing same
US3977888A (en) * 1969-12-08 1976-08-31 Kansai Paint Company, Ltd. Inorganic coating compositions with alkali silicate
US4259409A (en) * 1980-03-06 1981-03-31 Ses, Incorporated Electroless plating process for glass or ceramic bodies and product
US4466832A (en) * 1981-11-06 1984-08-21 Daikin Kogyo Company, Limited Composition for forming hydrophilic coating
US5068134A (en) * 1988-06-20 1991-11-26 Zaclon Corporation Method of protecting galvanized steel from corrosion
US5487919A (en) * 1990-04-09 1996-01-30 Kawasaki Steel Corporation Method of manufacturing of galvanized steel sheet having high press formability
US5108793A (en) * 1990-12-24 1992-04-28 Armco Steel Company, L.P. Steel sheet with enhanced corrosion resistance having a silane treated silicate coating
US5266412A (en) * 1991-07-15 1993-11-30 Technology Applications Group, Inc. Coated magnesium alloys
US5326594A (en) * 1992-12-02 1994-07-05 Armco Inc. Metal pretreated with an inorganic/organic composite coating with enhanced paint adhesion
US5478655A (en) * 1992-12-02 1995-12-26 Armco Inc. Metal pretreated with an inorganic/organic composite coating with enhanced paint adhesion
US5451431A (en) * 1993-11-16 1995-09-19 Betz Laboratories, Inc. Composition and process for treating metal surfaces
US5433976A (en) * 1994-03-07 1995-07-18 Armco, Inc. Metal pretreated with an aqueous solution containing a dissolved inorganic silicate or aluminate, an organofuctional silane and a non-functional silane for enhanced corrosion resistance
US5700523A (en) * 1996-06-03 1997-12-23 Bulk Chemicals, Inc. Method for treating metal surfaces using a silicate solution and a silane solution
US5759629A (en) * 1996-11-05 1998-06-02 University Of Cincinnati Method of preventing corrosion of metal sheet using vinyl silanes
US6033495A (en) * 1997-01-31 2000-03-07 Elisha Technologies Co Llc Aqueous gel compositions and use thereof
US6761934B2 (en) * 2001-08-03 2004-07-13 Elisha Holding Llc Electroless process for treating metallic surfaces and products formed thereby

Cited By (33)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050133651A1 (en) * 2003-10-31 2005-06-23 Chung Cheung Fishing reel gear mechanism coating
WO2008010824A2 (en) * 2005-09-13 2008-01-24 University Of South Carolina Improved catalysts for fuel cell applications using electroless deposition
WO2008010824A3 (en) * 2005-09-13 2008-07-03 Univ South Carolina Improved catalysts for fuel cell applications using electroless deposition
US20090117257A1 (en) * 2005-09-13 2009-05-07 University Of South Carolina Catalysts for Fuel Cell Applications Using Electroless Deposition
US20090220682A1 (en) * 2005-09-13 2009-09-03 University Of South Carolina catalysts for fuel cell applications using electroless deposition
US20100071938A1 (en) * 2007-08-31 2010-03-25 Kuhr Werner G Methods of treating a surface to promote metal plating and devices formed
US20090056991A1 (en) * 2007-08-31 2009-03-05 Kuhr Werner G Methods of Treating a Surface to Promote Binding of Molecule(s) of Interest, Coatings and Devices Formed Therefrom
US8323769B2 (en) 2007-08-31 2012-12-04 Atotech Deutschland Gmbh Methods of treating a surface to promote metal plating and devices formed
US20100075427A1 (en) * 2007-08-31 2010-03-25 Kuhr Werner G Methods of treating a surface to promote metal plating and devices formed
US20090225585A1 (en) * 2007-12-27 2009-09-10 Hawkins J Adrian Self-Contained Charge Storage Molecules for Use in Molecular Capacitors
EP2265441A1 (en) 2008-03-18 2010-12-29 Metal Coating Technologies, Llc Protective coatings for metals
WO2009117379A1 (en) * 2008-03-18 2009-09-24 Metal Coating Technologies, Llc Protective coatings for metals
KR101362969B1 (en) * 2008-03-18 2014-02-12 엠씨티 리서치 앤 디벨롭먼트 Protective coatings for metals
AU2009225791B2 (en) * 2008-03-18 2012-08-23 Mct Holdings Limited Protective coatings for metals
US20120196119A1 (en) * 2008-03-18 2012-08-02 Mct Research And Developement Protective coatings for metals
US8173221B2 (en) 2008-03-18 2012-05-08 MCT Research & Development Protective coatings for metals
US20090239065A1 (en) * 2008-03-18 2009-09-24 Metal Coating Technologies, Llc Protective coatings for metals
US20100068604A1 (en) * 2008-07-14 2010-03-18 Hawkins J Adrian Phosphonium Ionic Liquids, Compositions, Methods of Making and Electrolytic Films Formed There From
US8846246B2 (en) 2008-07-14 2014-09-30 Esionic Es, Inc. Phosphonium ionic liquids, compositions, methods of making and electrolytic films formed there from
US20100006794A1 (en) * 2008-07-14 2010-01-14 Hawkins J Adrian Phosphonium Ionic Liquids, Compositions, Methods of Making and Devices Formed There From
US20100006797A1 (en) * 2008-07-14 2010-01-14 Hawkins J Adrian Heat Transfer Medium, Phosphonium Ionic Liquids, and Methods of Making
US8927775B2 (en) 2008-07-14 2015-01-06 Esionic Es, Inc. Phosphonium ionic liquids, salts, compositions, methods of making and devices formed there from
US8525155B2 (en) 2008-07-14 2013-09-03 Esionic Es, Inc. Phosphonium ionic liquids, compositions, methods of making and electronic devices formed there from
US20100118598A1 (en) * 2008-07-14 2010-05-13 Hawkins J Adrian Phosphonium Ionic Liquids, Compositions, Methods of Making and Electronic Devices Formed There From
US8586797B2 (en) 2008-07-14 2013-11-19 Esionic Es, Inc. Phosphonium ionic liquids, compositions, methods of making and devices formed there from
US20100009255A1 (en) * 2008-07-14 2010-01-14 Hawkins J Adrian Phosphonium Ionic Liquids, Compositions, Methods of Making and Batteries Formed There From
US8778534B2 (en) 2008-07-14 2014-07-15 Esionic Es, Inc. Phosphonium ionic liquids, compositions, methods of making and batteries formed there from
US8586798B2 (en) 2008-07-14 2013-11-19 Esionic Es, Inc. Heat transfer medium, phosphonium ionic liquids, and methods of making
US8907133B2 (en) 2008-07-14 2014-12-09 Esionic Es, Inc. Electrolyte compositions and electrochemical double layer capacitors formed there from
CN102190911A (en) * 2010-03-09 2011-09-21 中国科学院上海硅酸盐研究所 Tungsten cobalt carbide-copper-fluoride self-lubricating wear-resistant coating and preparation method thereof
US9345149B2 (en) 2010-07-06 2016-05-17 Esionic Corp. Methods of treating copper surfaces for enhancing adhesion to organic substrates for use in printed circuit boards
US9795040B2 (en) 2010-07-06 2017-10-17 Namics Corporation Methods of treating copper surfaces for enhancing adhesion to organic substrates for use in printed circuit boards
US9435036B2 (en) * 2014-09-08 2016-09-06 Mct Holdings Ltd Silicate coatings

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AU2002355856A1 (en) 2003-02-17
EP1492904A2 (en) 2005-01-05
BR0211639A (en) 2005-06-28
CN1639386A (en) 2005-07-13
WO2003012167A2 (en) 2003-02-13
WO2003012167A3 (en) 2004-10-14
US20030118861A1 (en) 2003-06-26
US20040161603A1 (en) 2004-08-19
JP2005511887A (en) 2005-04-28
KR20040030925A (en) 2004-04-09
US6761934B2 (en) 2004-07-13

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