WO2006110756A1 - Article resistant a la corrosion et son procede de production - Google Patents

Article resistant a la corrosion et son procede de production Download PDF

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Publication number
WO2006110756A1
WO2006110756A1 PCT/US2006/013485 US2006013485W WO2006110756A1 WO 2006110756 A1 WO2006110756 A1 WO 2006110756A1 US 2006013485 W US2006013485 W US 2006013485W WO 2006110756 A1 WO2006110756 A1 WO 2006110756A1
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WO
WIPO (PCT)
Prior art keywords
article
layer
silicate
zinc
lubricant
Prior art date
Application number
PCT/US2006/013485
Other languages
English (en)
Inventor
Klaus Peter Klos
Original Assignee
Elisha Holding Llc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from EP05007883A external-priority patent/EP1712659A1/fr
Application filed by Elisha Holding Llc filed Critical Elisha Holding Llc
Publication of WO2006110756A1 publication Critical patent/WO2006110756A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C23—COATING 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
    • C23C—COATING 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
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING 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
    • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C09D5/08—Anti-corrosive paints
    • C09D5/082—Anti-corrosive paints characterised by the anti-corrosive pigment
    • C09D5/084—Inorganic compounds
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING 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
    • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C09D5/08—Anti-corrosive paints
    • C09D5/082—Anti-corrosive paints characterised by the anti-corrosive pigment
    • C09D5/086—Organic or non-macromolecular compounds
    • C—CHEMISTRY; METALLURGY
    • C23—COATING 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
    • C23C—COATING 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
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
    • C23C28/32—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer
    • C23C28/321—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer with at least one metal alloy layer
    • C—CHEMISTRY; METALLURGY
    • C23—COATING 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
    • C23C—COATING 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
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
    • C23C28/32—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer
    • C23C28/322—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer only coatings of metal elements only
    • C—CHEMISTRY; METALLURGY
    • C23—COATING 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
    • C23C—COATING 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
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
    • C23C28/32—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer
    • C23C28/322—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer only coatings of metal elements only
    • C23C28/3225—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer only coatings of metal elements only with at least one zinc-based layer
    • C—CHEMISTRY; METALLURGY
    • C23—COATING 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
    • C23C—COATING 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
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
    • C23C28/34—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates
    • C—CHEMISTRY; METALLURGY
    • C23—COATING 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
    • C23C—COATING 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
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
    • C23C28/34—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates
    • C23C28/345—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates with at least one oxide layer
    • C—CHEMISTRY; METALLURGY
    • C23—COATING 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
    • C23C—COATING 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
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
    • C23C28/34—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates
    • C23C28/347—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates with layers adapted for cutting tools or wear applications
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/48—After-treatment of electroplated surfaces
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D9/00—Electrolytic coating other than with metals
    • C25D9/04—Electrolytic coating other than with metals with inorganic materials
    • C25D9/08—Electrolytic coating other than with metals with inorganic materials by cathodic processes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
    • F16B33/00—Features common to bolt and nut
    • F16B33/008—Corrosion preventing means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
    • F16B33/00—Features common to bolt and nut
    • F16B33/06—Surface treatment of parts furnished with screw-thread, e.g. for preventing seizure or fretting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D5/00—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures
    • B05D5/08—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures to obtain an anti-friction or anti-adhesive surface

Definitions

  • the instant invention relates to corrosion resistant articles and a method of production thereof.
  • the instant invention relates to corrosion resistant articles comprising a threaded surface for engaging a corresponding threaded mating part such as, for example, bolts and nuts.
  • the corrosion resistant article of the instant invention can be used, for example, as a fastening element in motor vehicles such as, for example, a bolt or a nut for fastening the wheel rim to the wheel hub of an automobile ("wheel bolt” or "wheel nut”).
  • Safety sensitive automobile components such as wheel bolts and wheel nuts for motor vehicles must meet strict requirements with regard to corrosion and wear resistance as well as to friction properties.
  • Such automobile parts are exposed to severe outdoor environments including road water and rock salt and, hence, are required to have high degrees of corrosion resistance, impact strength and mechanical wear resistance.
  • automobile wheel bolts and wheel nuts undergo severe temperature changes during the operation of an automobile. Hence, it is required that such bolts and nuts do not loosen when they undergo temperature changes and, at the same time, the thread does not become stuck due to corrosion.
  • the automobile industry requires that bolts and nuts for this purpose have a total coefficient of friction ⁇ to t a i as determined by DIN 946 of the German Institute for Standards of 0.05 to 0.18.
  • hexavalent chromium a substance that is conventionally employed in galvanization processes used for imparting anti-corrosion properties to automobile parts. It is, therefore, desirable to produce bolts and nuts for automobiles that do not contain any environmentally incompatible substances such as hexavalent chromium.
  • chromium (VI) based coating systems Conventional wheel bolts and wheel nuts for use in automobiles contain chromium (VI) based coating systems. Such conventional wheel bolts and wheel nuts generally contain a protective coating of the following type: (a) a Zn or Zn/Ni layer; (b) a chromium (VI) based layer; and (c) a lubricant layer. While such systems have acceptable corrosion, wear and friction properties, the disadvantage of chromium (VI) based systems is their environmental incompatibility. 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. Using "Silicates as Cleaners in the Production of Tinplate" is described by LJ. Brown in February 1966 edition of Plating; hereby incorporated by reference.
  • the instant invention solves problems associated with conventional fastening elements by providing an article such as wheel bolt or a wheel nut for use in automobiles that has improved corrosion, wear, and friction properties and is environmentally acceptable. Further benefits of the invention will become apparent from a consideration of the ensuing description and drawings.
  • the instant invention provides a corrosion resistant article comprising a metal body and a protective coating applied on at least one surface of said metal body, said protective coating comprising: (a) a zinc layer comprising zinc; (b) a silicate layer comprising at least one silicate; and (c) a lubricant layer comprising at least one lubricant, wherein the article has a total coefficient of friction ⁇ tota ⁇ as determined by DIN 946 of about 0.05 to about 0.20.
  • the instant invention provides a multi-layer protective coating for metal articles - such as fastening elements for use in motor vehicles - which satisfies the problems discussed above in that it is highly resistant to chemical attack, has good friction properties and shows excellent temperature resistance.
  • the multi-layer protective coating of the instant invention is substantially free of chromates (hexavalent and trivalent) and phosphates and, hence, is environmentally safe.
  • the multi-layer coated metal article of the instant invention can possess improved corrosion resistance, increased electrical resistance, heat resistance, flexibility, resistance to stress crack corrosion, adhesion to topcoats, among other properties.
  • the treated surface imparts greater corrosion resistance (e.g., ASTM B-117), among other beneficial properties, than conventional trivalent or hexavalent chromate systems.
  • the articles of the instant invention have a ASTM B 117 exposure to white rust of greater than, for example, about 200 hours, preferably greater than, for example, about 400 hours and most preferred greater than, for example, about 1000 hours.
  • the articles of the instant invention have a total coefficient of friction ⁇ tota i as determined by DIN 946 (October 1991) of the German Institute for Standards of about 0.05 to about 0.20. Furthermore, it was found that the total coefficient of friction ⁇ tota i increases by less than about 0.05, in particular by less than about 0.03, after the article has been fastened repeatedly for 10 times.
  • the articles of the instant invention have a loosening torque that amount to at least 50 % of the fastening torque when measured at at least one (preferably all) of the following conditions:
  • the ratio R of the loosening torque N2 (in Nm) to the fastening torque Nl (in Nm) of the articles of the instant invention as determined by the equation R [%] 100 xN2/Nl was found to be greater 50 % for each of the conditions (a) to (d) as defined above.
  • the articles of the instant invention can be used as safety sensitive automobile components such as wheel bolts and wheel nuts.
  • the invention further provides a process for manufacturing multilayer coated corrosion resistant articles, such as fastening elements for automobiles.
  • 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.
  • the 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, cobalt, 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.
  • the inventive method forms a layer having greater heat resistance, flexibility, among other properties, than conventional chromate coatings.
  • the improved heat resistance broadens the range of processes that can be performed subsequent to forming the inventive layer, e.g., heat cured topcoatings, bending, deforming, stamping/shaping, riveting, among other processes.
  • the instant invention employs silicates in an electrolytic (e.g. cathodic) process or in an electroless process for forming a mineral layer upon the substrate.
  • electrolytic e.g. cathodic
  • electroless process for forming a mineral layer upon the substrate.
  • Conventional electrocleaning processes sought to avoid formation of oxide containing products such as greenalite whereas the instant invention relates to a method for forming silicate containing products, e.g., a mineral.
  • FIG. 1 is a perspective view of a corrosion resistant coated bolt according to an embodiment of the instant invention as described in Example 1.
  • the corrosion resistant articles according to the instant invention are usually a metal body such as steel articles having a protective coating applied thereon, such as, for example, fastening elements for use in automobiles.
  • the corrosion resistant articles according to the instant invention are usually fastening elements comprising a threaded surface for engaging a corresponding threaded mating part such as, for example, bolts and nuts (especially bolts and nuts for fastening automobile wheels).
  • the corrosion resistant article according to the instant invention comprises a metal body and a protective coating applied on at least one surface of said metal body.
  • the protective coating is normally applied upon an exterior surface (as is, for example, the case for bolts) but can also be applied upon interior surfaces (as is, for example, the case in nuts).
  • the metal body to be coated in accordance with the instant invention can possess a wide range of sizes and configurations, e.g., tubes, 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 metal body is a fastening element comprising a threaded surface for engaging a corresponding threaded mating part.
  • metal body refers to a metal article or body as well as a non- metallic or non-conductive substrate having at least one surface coated with an electrically conductive material.
  • suitable metal articles or bodies comprise at least one member selected from the group consisting of galvanized surfaces, hot-dipped galvanized, sheradized surfaces, zinc, iron, steel, brass, copper, silver, barium, calcium, strontium, titanium, zirconium, tin, lead, manganese, iron, iron alloys, nickel, tin, aluminum, lead, cadmium, magnesium, alloys thereof such as zinc-nickel alloys, tin-zinc alloys, zinc- cobalt alloys, and zinc-iron alloys, among others.
  • Suitable non-conductive substrates having at least one surface coated with an electrically conductive material include, for example, 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) 5 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 corrosion resistant article may be beneficial to clean the metal body before it enters the coating process, such as by use of suitable electrolytic degreasing; preferably with a method which avoids excessive hydrogen diffusion into the article, and decapping operations as are typically used in the art of zinc plating and having due regard to the particular metal body to be coated.
  • the articles can be cleaned by an acid such as hydrochloric or citric acid, rinsed with water, and rinsed with an alkali such as sodium hydroxide, rinsed again with water. The cleaning and rinsing can be repeated as necessary. If desired the acid/alkali cleaning can be replaced with a conventional sonic cleaning apparatus.
  • the metal body is coated with a protective coating.
  • the protective coating comprises at least the following layers:
  • silicate layer comprising at least one silicate
  • a lubricant layer comprising at least one lubricant.
  • the protective coating is not limited to the aforesaid layers but may comprise, for example, additional layers such as, for example, an a corrosion protection layer interposed between the silicate layer and the lubricant layer.
  • the zinc layer is an electrolytically applied zinc that can be applied by conventional electrolytic methods.
  • electrolytic methods are generally known and widely used in the art.
  • the zinc layer typically has a thickness of, for example, about 1 to about 75 micrometers; in particular, the zinc layer typically has a thickness of, for example, about 15 to about 35 micrometers.
  • the silicate layer is formed by an electrolytic (e.g. cathodic) process as will be described in more detail below.
  • the silicate layer typically has a thickness of, for example, about 50 to 800 A.
  • a lubricant layer containing a lubricant such as, for example, polyethylene wax.
  • the lubricant layer typically has a thickness of, for example, about 0.01 to about 5 micrometers, in particular of about 0.1 to about 1 micrometer.
  • the presence of the silicate layer - in combination with the other layers of the protective coating - is largely responsible for such beneficial properties of the corrosion resistant article of the instant invention as improved corrosion resistance, improved friction properties, increased electrical resistance, heat resistance, flexibility, and resistance to stress crack corrosion, among other properties.
  • the zinc layer can be formed by immersion in molten zinc metal (hot dipped galvanization), mechanical plated, among other methods for forming a zinc containing layer.
  • the coating of the metal body can be accomplished in various ways, some of which will be explained in more detail by way of example in the following: 1.
  • zinc layer it is meant any layer that contains metallic zinc or an alloy thereof such as Zn/Ni, Zn/Fe, Sn/Zn, among other zinc containing layers.
  • the zinc layer of the instant invention can also contain additional components besides metallic zinc.
  • a Zn/Ni layer can be applied in a similar manner as a Zn layer by conventional electrolytic methods that are generally known and widely used in the art. In Zn/Ni plating the electrolyte usually contains hydrochloric acid rather than sulfuric acid.
  • the silicate layer can be applied by a cathodic method for forming a protective layer upon a metallic or metal containing substrate (e.g., the protective layer can range from about 10 to about 2,500 Angstroms thick).
  • the cathodic method is normally conducted by contacting (e.g., immersing) a substrate having an electrically conductive surface into a silicate containing bath or medium wherein a current is introduced to (e.g., passed through) the bath and the substrate is the cathode.
  • the inventive process can form 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.
  • 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 or an electrically conductive surface.
  • a beneficial surface e.g., a mineral containing coating or film
  • the process employs a silicate medium, e.g., containing soluble mineral components or precursors thereof, and utilizes an electroless or an electrically enhanced method to treat an electrically conductive surface (e.g., to obtain a mineral coating or film upon a metallic or conductive surface).
  • electrolytic or “electrodeposition” or “electrically enhanced” it is meant to refer to an environment created by introducing or passing an electrical current through a silicate containing medium while in contact with an electrically conductive substrate (or having an electrically conductive surface) and wherein the substrate functions as the cathode.
  • metal containing metal
  • 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 electrolytic environment can be established in any suitable manner including immersing the substrate, applying a silicate containing coating upon the substrate and thereafter applying an electrical current, among others.
  • the preferred method for establishing the environment will be determined by the size of the substrate, electrodeposition time, applied voltage, among other parameters known in the electrodeposition art.
  • the effectiveness of the electrolytic environment can be enhanced by supplying energy in the form of ultrasonic, laser, ultraviolet light, RF, IR, among others.
  • the inventive process can be operated on a batch or continuous basis.
  • the silicate containing medium can be a fluid bath, gel, spray, 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 ammonium silicate, potassium silicate, calcium silicate, lithium silicate, sodium silicate, compounds releasing silicate moieties or species, among other silicates.
  • the bath can comprise any suitable polar carrier such as water, alcohol, ethers, among others.
  • the bath comprises sodium silicate and de-ionized water and optionally at least one dopant.
  • 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 11.
  • the medium is normally aqueous and can comprise at least one water soluble or dispersible silicate in an amount from greater than 0 to about 40 wt.%, usually, about 3 to 15 wt.% and typically about 10wt.%.
  • the silicate medium can further comprise at least one water dispersible or soluble dopant.
  • the silicate containing medium is also normally substantially free of heavy metals, chromates and/or phosphates.
  • the silicate containing medium can also include silica.
  • the silica can be colloidal with a particle size ranging from about lOnm to about 50nm.
  • the size of particles in the medium ranges from about lOnm to 1 micron and typically about 0.05 to about 0.2 micron.
  • the medium can have a turbidity of about 10 to about 850, typically about 50 to about 300 Nephelometric Turbidity Units (NTU) as determined in accordance with conventional procedures.
  • NTU Nephelometric Turbidity Units
  • the electrolytic environment can be preceded by and/or followed with conventional post and/or pre-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 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.
  • the post-treated surface can be sealed, rinsed and/or topcoated, e.g., silane, epoxy, latex, fluoropolymer, acrylic, titanates, zirconates, carbonates, among other coatings.
  • the 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. Patent 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 heating the surface.
  • the amount of heating is sufficient to density 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. 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.
  • 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, among other acid sources effective at improving at least one property of the treated metal surface.
  • the pH of the acid post treatment can 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 5 wt.% and typically, about 1 to about 2 wt.%.
  • 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 ® ), silanes, siloxanes, nitrates such as aluminum nitrate; sulphates such as magnesium sulphate, sodium sulphate, zinc sulphate, 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, among others.
  • organic compound such as vinyl acrylics, fluorosurfactancts, polyethylene wax, among others.
  • commercially available rinses comprise at least one member selected from the group of Aqualac ® (urethane containing aqueous solution), W86 ® , W87 ® , B37 ® , T01 ® , E10 ® , among others (a heat cured coating supplied by the Magni ® Group), JS2030S (sodium silicate containing rinse supplied by MacDermid Incorporated), JS2040I (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 (
  • One specific rinse comprises water, water dispersible urethane, and at least one silicate, e.g., refer to commonly assigned U.S. Patent 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 metal surface refers to a metal article or body as well as a non- metallic or an electrically conductive member having an adhered metal or conductive layer.
  • suitable metal surfaces comprise at least one member selected from the group consisting of galvanized surfaces (e.g. the zinc plated metal article from the previous step), 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 an electrically conductive material, 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 electrical current/energy to contact the metal surface. That is, similar to conventional electroplating technologies, a mineral surface may be difficult to apply upon a metal surface defining hollow areas or voids.
  • the inventive process creates 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 fluoroplastic resin), 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 provides 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 inventive process is employed for improving the cracking and oxidation resistance of aluminum, copper or lead containing substrates.
  • lead which is used extensively in battery production, is prone to corrosion that in turn causes cracking, e.g., inter- granular corrosion.
  • the inventive process can be employed for promoting grain growth of aluminum, copper and lead substrates as well as reducing the impact of surface flaws.
  • the lattice structure of the mineral layer formed in accordance with the inventive process on these 3 types of substrates can be a partially polymerized silicate. These lattices can incorporate a disilicate structure, or a chain silicate such as a pyroxene.
  • a partially polymerized silicate lattice offers structural rigidity without being brittle.
  • metal cations would preferably occupy the lattice to provide charge stability.
  • Aluminum has the unique ability to occupy either the octahedral site or the tetrahedral site in place of silicon. The +3 valence of aluminum would require additional metal cations to replace the +4 valance of silicon. In the case of lead application, additional cation can comprise +2 lead ion.
  • an electrogalvanized panel e.g., a zinc surface
  • a mineral coating or film containing silicates is deposited by using relatively low voltage potential (e.g., about 1 to about 24 v depending upon the desired current density) and low current.
  • the current density can range from about 0.7A/in 2 to about 0.1 A/in 2 at 12 volt constant.
  • hydrogen is evolved at the workpiece/cathode and oxygen at the anode.
  • the workpiece is initially employed as an anode and then electrically switched (or pulsed) to the cathode.
  • the workpiece By pulsing the voltage, the workpiece can be pre-treated in-situ (prior to interaction with the electrolytic medium). Pulsing can also increase the thickness of the film or layer formed upon the workpiece.
  • dopants e.g., cations
  • the workpiece is treated by a bipolar technique as described in WO 2004/097069 A2.
  • a bipolar technique as described in WO 2004/097069 A2.
  • An apparatus suitable for such dipole coating is described in Fig. 4 and the corresponding passages of the specification of WO 2004/097069 A2, incorporated herein by reference.
  • the bipolar technique has proven to be particularly advantageous for treating threaded articles as workpieces such as nuts and bolts.
  • the metal surface e.g., zinc, aluminum, magnesium, steel, lead and alloys thereof; has an optional pretreatment.
  • pretreatment it is meant to refer to a batch or continuous process for conditioning the metal surface to clean it and condition the surface to facilitate acceptance of the mineral or silicate containing coating e.g., the inventive process can be employed as a step in a continuous process for producing corrosion resistant coil steel.
  • the particular pretreatment will be a function of composition of the metal surface and desired functionality of the mineral containing coating/film to be formed on the surface.
  • Suitable pre-treatments comprise at least one of cleaning, e.g., sonic cleaning, activating, heating, degreasing, pickling, deoxidizing, shot glass bead blasting, sand blasting and rinsing.
  • cleaning e.g., sonic cleaning, activating, heating, degreasing, pickling, deoxidizing, shot glass bead blasting, sand blasting and rinsing.
  • the metal surface is pretreated by anodically cleaning the surface.
  • cleaning can be accomplished by immersing the work piece or substrate into a medium comprising silicates, hydroxides, phosphates, carbonates, among other cleaning agents.
  • 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 work piece is exposed to the inventive silicate medium as an anode thereby cleaning the work piece (e.g., removing naturally occurring compounds).
  • the work piece can then converted to the cathode and processed in accordance with the inventive methods.
  • the silicate medium is modified to include at least one dopant material.
  • 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.% (or greater so long as the electrolyte is not adversely affected.
  • Suitable dopants comprise at least one member selected from the group of water soluble salts, oxides and precursors of tungsten, molybdenum, chromium, titanium (titatantes), zircon, vanadium, phosphorus, aluminum (aluminates), iron (e.g., iron chloride), boron (borates), bismuth, gallium, tellurium, germanium, antimony, niobium (also known as columbium), magnesium and manganese, sulfur, zirconium (zirconates) mixtures thereof, among others, and usually, salts and oxides of aluminum and iron.
  • chromium titanium (titatantes), zircon, vanadium, phosphorus, aluminum (aluminates), iron (e.g., iron chloride), boron (borates), bismuth, gallium, tellurium, germanium, antimony, niobium (also known as columbium), magnesium and manganese, sulfur, zirconium (zirconates) mixtures thereof,
  • 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 , (NELO 2 ZrFg 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 , (NELO 2 ZrFg 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, metal oxides such as cerium oxide, powdered metals and metallic precursors such as zinc, among others.
  • PTFE electropheritic transportable polymers
  • boron nitride silicon carbide
  • silicon nitride silicon nitride
  • aluminum nitride titanium carbide
  • diamond titanium diboride
  • tungsten carbide metal oxides such as cerium oxide
  • powdered metals and metallic precursors such as zinc
  • dopants examples include iron salts (ferrous chloride, sulfate, nitrate), aluminum fluoride, fluorosilicates (e.g., K 2 SiF 6 ), fiuoroaluminates (e.g., potassium fluoroaluminate such as K 2 AlF 5 - H 2 O), mixtures thereof, among other sources of metals and halogens.
  • iron salts ferrous chloride, sulfate, nitrate
  • aluminum fluoride fluorosilicates
  • fluorosilicates e.g., K 2 SiF 6
  • fiuoroaluminates e.g., potassium fluoroaluminate such as K 2 AlF 5 - H 2 O
  • the dopant materials can be introduced to the metal or conductive surface in pretreatment steps prior to electrodeposition, in post treatment steps following electrodeposition (e.g., rinse), and/or by alternating electrolytic contacts in 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 electrolyte solution can be employed to form tailored surfaces upon the metal or conductive surface, 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.
  • at least one dopant e.g., zinc
  • siliceous species e.g., a mineral
  • the silicate medium can also be modified by adding at least one diluent or electrolyte.
  • suitable diluent comprise at least one member selected from the group of sodium sulphate, surfactants, de-foamers, colorants/dyes, among others.
  • the diluent e.g., sodium sulfate
  • the amount normally comprises less than about 5 wt.% of the electrolyte, e.g., about 1 to about 2 wt.%.
  • a diluent for affecting the electrical conductivity of the bath or electrolyte is normally in employed in an amount of about 0 wt.% to about 20 wt.%.
  • the temperature of the electrolyte bath ranges from about 25 to about 95 0 C (e.g., about 75 0 C), the voltage from about 6 to 24 volts, an electrolyte solution concentration from about 5 to about 15 wt.% silicate, the current density ranges from about 0.025A/in 2 and greater than 0.60A/in 2 (e.g., about 180 to about 200 mA/cm2 and normally about 192 mA/cm 2 ), contact time with the electrolyte from about 10 seconds to about 50 minutes and normally about 1 to about 15 minutes and anode to cathode surface area ratio of about 0.5:1 to about 2:1.
  • Items 1, 2, 7, and 8 can be especially effective in tailoring the chemical and physical characteristics of the coating. That is, items 1 and 2 can affect the deposition time and coating thickness whereas items 7 and 8 can be employed for introducing dopants that impart desirable chemical characteristics to the coating.
  • the differing types of anions and cations can comprise at least one member selected from the group consisting of Group I metals, Group II metals, transition and rare earth metal oxides, oxyanions such as molybdate, phosphate, titanate, boron nitride, silicon carbide, aluminum nitride, silicon nitride, mixtures thereof, among others.
  • the typical process conditions will provide an environment wherein hydrogen is evolved at the cathode and oxygen at the anode. Without wishing to be bound by any theory or explanation, it is believed that the hydrogen evolution provides a relatively high pH at the surface to be treated. It is also believed that the oxygen reduced or deprived environment along with a high pH can cause an interaction or a reaction at the surface of the substrate being treated. It is further believed that zinc can function as a barrier to hydrogen thereby reducing, if not eliminating, hydrogen embrittlement being caused by operating the inventive process.
  • inventive process can be modified by employing apparatus and methods conventionally associated with electroplating processes.
  • inventive processes include pulse plating, horizontal plating systems, barrel, rack, adding electrolyte modifiers to the silicate containing medium, employing membranes within the bath, among other apparatus and methods.
  • the inventive process can be modified by varying the composition of the anode.
  • suitable anodes comprise graphite, platinum, zinc, iron, steel, iridium oxide, beryllium oxide, tantalum, niobium, titanium, nickel, Monel ® alloys, pallidum, alloys thereof, among others.
  • the anode can comprise a first material clad onto a second, e.g., platinum plated titanium or platinum clad niobium mesh.
  • the anode can possess any suitable configuration, e.g., mesh adjacent to a barrel plating system.
  • the anode e.g., iron or nickel
  • ppm concentrations of anode ions are sufficient to affect the mineral layer composition. If a dimensionally stable anode is desired, then platinum clad or plated niobium can be employed. In the event a dimensionally stable anode requires cleaning, in most cases the anode can be cleaned with sodium hydroxide solutions. Anode cleaning can be enhanced by using heat and/or electrical current.
  • the inventive process can be practiced in any suitable apparatus.
  • suitable apparatus comprise rack and barrel plating, brush plating, horizontal plating, continuous lengths, among other apparatus conventionally used in electroplating metals.
  • the workpiece is subjected to the inventive electrolytic method thereby forming a mineral coating upon at least a portion of the workpiece surface. After formation of the mineral coating the workpiece is removed from the electrolytic environment, dried and rinsed with water, e.g, a layer comprising, for example, silica and/or sodium carbonate can be removed by rinsing.
  • the inventive process also imparts improved torque tension properties in comparison to conventional chromate processes (hex or trivalent).
  • Wilson- Garner MlO bolts were coated with conventional zinc and yellow hexavalent chromate, and treated in accordance with the inventive process.
  • the torque tension of these bolts was tested in accordance with test protocol USCAR-Il at forces from about 20,000 to about 42,300 Newtons.
  • the standard deviation for the peak torque for the conventional zinc/yellow chromate treated bolts was about 5.57 Nm with a three-sigma range of about 33.4, and about 2.56 Nm with a three-sigma range of 15.4 for bolts treated in accordance with the inventive process.
  • the surface formed by the inventive process may or may not be rinsed prior to applying a topcoat. Normally, the surface formed by the inventive process will be rinsed, e.g., with at least one of deionized water, silane or a carbonate, prior to applying a topcoat, e.g. a fluoroplastic resin.
  • a silica containing layer can be formed upon the mineral.
  • 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.
  • silica containing layer can be removed by using conventional cleaning methods, e.g, rinsing with de-ionized water.
  • the silica containing tie-layer can be relatively thin in comparison to the mineral layer 100-500 angstroms compared to the total thickness of the mineral which can be 1500-2500 angstroms thick.
  • 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 a topcoat, e.g, a fluoroplastic resin.
  • the mineral without or without the aforementioned silica 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. Patent 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 tetra-ortho-ethyl-silicate (TEOS), bis-1 ,2-(triethoxysilyl) ethane (BSTE), vinyl silane or aminopropyl silane, epoxy silanes, alkoxysilanes, among other organo functional silanes.
  • TEOS tetra-ortho-ethyl-silicate
  • BSTE bis-1 ,2-(triethoxysilyl) ethanethane
  • vinyl silane or aminopropyl silane epoxy silanes, alkoxysilanes, 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.
  • the inventive process forms a surface that has improved adhesion to outer coatings or layers, e.g., secondary coatings such as, for example, fluoroplastic resins.
  • outer coatings or layers e.g., secondary coatings such as, for example, fluoroplastic resins.
  • 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.
  • Suitable lubricants for this purpose include molybdenum sulfide, fluorinated polymers (in particular teflon), waxes (in particular polymer based waxes such as polyethylene waxes, polyvinylether waxes, ethylene copolymer waxes, montanic acid waxes, and montanic ester waxes), wax esters, paraffines, stearates, graphite, oils (in particular silicon oils), and mixtures hereof.
  • fluorinated polymers in particular teflon
  • waxes in particular polymer based waxes such as polyethylene waxes, polyvinylether waxes, ethylene copolymer waxes, montanic acid waxes, and montanic ester waxes
  • wax esters paraffines, stearates, graphite, oils (in particular silicon oils), and mixtures hereof.
  • the lubricant layer may be formed by immersing the workpiece in a lubricant medium such as, for example, an aqueous dispersion of the lubricant, removing excess lubricant medium, if any, and subsequently drying the work piece. Removing excess lubricant medium can be effected, for example, by using a centrifuge. Drying of the work piece can be effected, for example, by allowing hot air (e.g., at temperatures of 40 to 100 0 C) to pass by the work pieces.
  • a lubricant medium such as, for example, an aqueous dispersion of the lubricant, removing excess lubricant medium, if any, and subsequently drying the work piece. Removing excess lubricant medium can be effected, for example, by using a centrifuge. Drying of the work piece can be effected, for example, by allowing hot air (e.g., at temperatures of 40 to 100 0 C) to pass by the work pieces
  • the lubricant layer additionally contains at least one corrosion protection agent such as, for example, an acrylate dispersion, in an amount of, for example, 0.01 to 10 wt.%, order to enhance the corrosion resistance properties of the article.
  • at least one corrosion protection agent such as, for example, an acrylate dispersion
  • the lubricant layer is usually applied at a thickness of, for example, about 0.01 to about 5 micrometers, in particular of about 0.1 to about 1 micrometers.
  • Suitable corrosion protection agents for threaded mechanical fastening elements are well known in the art and include, for example, acrylate dispersions.
  • the corrosion protection layer can be applied as a single layer or, optionally, as two or more layers.
  • the application of the corrosion protection layer can be effected by any suitable method such as spraying, showering, immersing, and/or brush-coating.
  • the primer can be formed by immersing and subsequent air drying.
  • the corrosion protection layer is applied at a thickness of, for example, about 0.1 to about 20 micrometers.
  • a M8 standard bolt of 45 mm length with a metric thread of the type as depicted in Fig. 1 were barrel coated in a process in accordance with the following procedure:
  • Zinc plating laver A zinc plating layer of about 10 micrometer thickness was cathodically formed on the outer surface of the bolt by employing a potassium based zinc bath at pH 5.5 to 6.0 containing 40 g/1 Zn 2+ (as ZnCl 2 ), 135 g/1 chloride (as KCl and ZnCl 2 ), and 25 g/1 boric acid and additionally wetting agents and brighteners and applying an electric current at a density of 0,5-1 A/dm 2 at a temperature of 25-32 0 C.
  • the bolt Prior to zinc electroplating the bolt was thoroughly cleaned by placing it, consecutively, in an alkaline soak bath (lOOg/1 NaOH + tensides at 60-70 0 C) an acidic pickle bath (50 % HCl at 23 0 C), and an alkaline electrolyte bath (50 g/1 NaOH + 20 g/1 sodium gluconate at 60-70 0 C).
  • an alkaline soak bath laOOg/1 NaOH + tensides at 60-70 0 C
  • an acidic pickle bath 50 % HCl at 23 0 C
  • an alkaline electrolyte bath 50 g/1 NaOH + 20 g/1 sodium gluconate at 60-70 0 C.
  • the coated bolt was rinsed with water by placing it in a rinse bath.
  • Silicate film A silicate film of approximately 200-300 A thickness was cathodically formed on the zinc plating layer obtained in step (2) by employing an alkaline electrolyte (pH 10.6) containing 10 % by weight sodium silicate (NajSiOa) in water and applying an electric current at a density of 0.5-1 A/dm 2 at a temperature of 75 0 C for about 15 minutes in a barrel.
  • an alkaline electrolyte pH 10.6
  • NajSiOa sodium silicate
  • the coated bolts were immediately rinsed with water by placing it in a rinse bath. After rinsing, the bolt was placed in an oven, heated to 95 0 C and dried at this temperature for 10- 15 minutes.
  • Lubricant layer A lubricant layer composed of polyethylene wax was applied by flushing the dried coated bolt subjected to treatments (2) and (3) above with a dispersion of polyethylene wax (Microgleit ® 911, Microgleit Spezialschmierstoffe GmbH, Hohenwart, Germany) in water. After flushing, the bolts were centrifuged and air dried at 70 0 C. The lubricant layer had a thickness of approximately 0.5 to 1 micrometers.
  • the temperature dependence of the ratio R of the loosening torque N2 to the fastening torque Nl of the bolts was determined by measuring the fastening torque Nl (in Nm) and the loosening torque N2 (in Nm) of the bolts at each of the following conditions:
  • the Example shows that the bolts having the mineral coating system of the instant invention have excellent friction properties with the measured total coefficients of friction falling in the narrow range of 0.06 to 0.08 even after several times of fastening and loosening. Furthermore, the results show that the bolts exhibit an excellent temperature resistance with the loosening torque of the bolts remaining above 50 % of the fastening torque even after heating to 150 and 200 0 C. respectively. Finally, the bolts exhibited excellent optical properties as well as corrosion properties and were successfully used as wheel bolts in automobiles.
  • a M8 standard bolt of 45 mm length with a metric thread of the type as depicted in Fig. 1 were coated in a batch process in accordance with the following procedure:
  • a zinc plating layer of approximately 15 ⁇ m thickness was formed in the same manner as in step (2) of the previous Example.
  • a chromium (III) plating layer of about 20 to 100 nanometers thickness was formed on the outer surface of the zinc plated bolt by placing the barrel for about 30 to 45 seconds in an acidic aqueous passivation bath at a temperature of 23-25 0 C.
  • the passivation bath was prepared in the following manner: (a) preparing an aqueous solution of 150 g/1 Cr(NO 3 ) 3 ' 9 H 2 0, 40 g/1 NaCl 5 and 100 g/1 NaNO 3 ; (b) diluting the solution from step (a) with water so that the resulting solution contains 25 ml/1 of the solution from step (a); and (c) adjusting the pH of the solution to about 1.8 with HNO 3 .
  • the Comparison Example shows that the chromium (HI) coating system yields satisfactory friction properties, the temperature resistance of the bolts is insufficient, with the loosening torque of the bolts going down to 43.7 and 40 % of the fastening torque after heating to 150 and 200 0 C, respectively. Due to their insufficient temperature resistance, the bolts of the Comparison Example are not suited for use as wheel bolts in automobiles.
  • HI chromium

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  • Inorganic Chemistry (AREA)
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  • Materials Engineering (AREA)
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  • General Engineering & Computer Science (AREA)
  • Electrochemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Wood Science & Technology (AREA)
  • Other Surface Treatments For Metallic Materials (AREA)
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Abstract

La présente invention concerne un article résistant à la corrosion comprenant un corps métallique et un revêtement protecteur appliqué sur au moins une surface dudit corps métallique. Ledit revêtement protecteur comporte (a) une couche de zinc contenant du zinc métallique, (b) une couche de silicate contenant au moins un silicate, et (c) une couche lubrifiante renfermant au moins un lubrifiant, tel que, par exemple, une cire de polyéthylène. Notamment, cette invention a pour objet une vis et/ou un écrou qui résistent à la corrosion, possèdent un revêtement protecteur et sont utilisés dans des véhicules motorisés. Ce revêtement protecteur est pratiquement exempt de chromates et de phosphates et, donc, acceptable du point de vue de l'environnement. L'article possède un excellent coefficient de friction, des propriétés de résistance thermique et d'anticorrosion.
PCT/US2006/013485 2005-04-11 2006-04-11 Article resistant a la corrosion et son procede de production WO2006110756A1 (fr)

Applications Claiming Priority (4)

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EP05007883A EP1712659A1 (fr) 2005-04-11 2005-04-11 Article résistant à la corrosion et méthode pour sa production
EP05007883.1 2005-04-11
US11/140,710 US7160630B2 (en) 2005-04-11 2005-05-31 Corrosion resistant article and method of production thereof
US11/140,710 2005-05-31

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010121005A1 (fr) * 2009-04-17 2010-10-21 Illinois Tool Works Inc. Composition chimique de revêtement pour pointe d'élément de fixation
WO2011007050A1 (fr) 2009-07-17 2011-01-20 Jorma Kinnunen Vis de montage, procédé et agencement
ES2389188A1 (es) * 2011-03-29 2012-10-24 Rovalma, S.A. Protección catódica mediante recubrimiento para circuitos de refrigeración u otros agujeros o canales.
WO2019203709A1 (fr) * 2018-04-19 2019-10-24 Provexa Ab Procédé de traitement de surface
IT201800004961A1 (it) * 2018-04-27 2019-10-27 Processo per il rivestimento anti-corrosione di minuteria metallica sottoposta a zincatura.
CN114887851A (zh) * 2022-06-08 2022-08-12 大连理工大学 一种核电重要厂离心泵紧固件的表面防腐方法
WO2022266739A1 (fr) * 2021-06-21 2022-12-29 Cia. Industrial H. Carlos Schneider Composition de revêtement et procédé respectif d'application sur des substrats métalliques

Citations (5)

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Publication number Priority date Publication date Assignee Title
US4555445A (en) * 1984-03-30 1985-11-26 Frey Gary T Corrosion resistant lubricant coating composite
US20030170483A1 (en) * 1998-08-18 2003-09-11 Ernst-Walter Hillebrand Coating system
JP2003306638A (ja) * 2002-04-16 2003-10-31 Yokogawa Bridge Corp ジンクリッチ塗料組成物
US20040127625A1 (en) * 2000-05-11 2004-07-01 Vittorio Clerici Coating composition
US20050037227A1 (en) * 2003-08-15 2005-02-17 Hoden Seimitsu Kako Kenkyusho Co., Ltd. Chromium-free metal surface treatment agent

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4555445A (en) * 1984-03-30 1985-11-26 Frey Gary T Corrosion resistant lubricant coating composite
US20030170483A1 (en) * 1998-08-18 2003-09-11 Ernst-Walter Hillebrand Coating system
US20040127625A1 (en) * 2000-05-11 2004-07-01 Vittorio Clerici Coating composition
JP2003306638A (ja) * 2002-04-16 2003-10-31 Yokogawa Bridge Corp ジンクリッチ塗料組成物
US20050037227A1 (en) * 2003-08-15 2005-02-17 Hoden Seimitsu Kako Kenkyusho Co., Ltd. Chromium-free metal surface treatment agent

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010121005A1 (fr) * 2009-04-17 2010-10-21 Illinois Tool Works Inc. Composition chimique de revêtement pour pointe d'élément de fixation
US8562268B2 (en) 2009-04-17 2013-10-22 Illinois Tool Works Inc. Fastener tip coating chemistry
US9725670B2 (en) 2009-04-17 2017-08-08 Illinois Tool Works Inc. Fastener tip coating
WO2011007050A1 (fr) 2009-07-17 2011-01-20 Jorma Kinnunen Vis de montage, procédé et agencement
EP2454496A4 (fr) * 2009-07-17 2018-01-17 Kingi Oy Vis de montage, procédé et agencement
ES2389188A1 (es) * 2011-03-29 2012-10-24 Rovalma, S.A. Protección catódica mediante recubrimiento para circuitos de refrigeración u otros agujeros o canales.
WO2019203709A1 (fr) * 2018-04-19 2019-10-24 Provexa Ab Procédé de traitement de surface
SE545567C2 (en) * 2018-04-19 2023-10-24 Provexa Ab Method for surface treatment
IT201800004961A1 (it) * 2018-04-27 2019-10-27 Processo per il rivestimento anti-corrosione di minuteria metallica sottoposta a zincatura.
WO2022266739A1 (fr) * 2021-06-21 2022-12-29 Cia. Industrial H. Carlos Schneider Composition de revêtement et procédé respectif d'application sur des substrats métalliques
CN114887851A (zh) * 2022-06-08 2022-08-12 大连理工大学 一种核电重要厂离心泵紧固件的表面防腐方法

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