Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D15/00—Electrolytic or electrophoretic production of coatings containing embedded materials, e.g. particles, whiskers, wires
  • C25D15/02—Combined electrolytic and electrophoretic processes with charged materials
• • 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
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
  • C23C18/31—Coating with metals
  • C23C18/32—Coating with nickel, cobalt or mixtures thereof with phosphorus or boron
  • C23C18/34—Coating with nickel, cobalt or mixtures thereof with phosphorus or boron using reducing agents
  • C23C18/36—Coating with nickel, cobalt or mixtures thereof with phosphorus or boron using reducing agents using hypophosphites
• • 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
  • C25D5/10—Electroplating with more than one layer of the same or of different metals
  • C25D5/12—Electroplating with more than one layer of the same or of different metals at least one layer being of nickel or chromium
  • C25D5/14—Electroplating with more than one layer of the same or of different metals at least one layer being of nickel or chromium two or more layers being of nickel or chromium, e.g. duplex or triplex layers
• • 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
  • C25D5/60—Electroplating characterised by the structure or texture of the layers
  • C25D5/623—Porosity of the layers
• • 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
  • C25D5/627—Electroplating characterised by the visual appearance of the layers, e.g. colour, brightness or mat appearance
• • Y—GENERAL 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
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S428/00—Stock material or miscellaneous articles
  • Y10S428/922—Static electricity metal bleed-off metallic stock
  • Y10S428/9335—Product by special process
  • Y10S428/934—Electrical process
  • Y10S428/935—Electroplating
• • Y—GENERAL 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
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12451—Macroscopically anomalous interface between layers
• • Y—GENERAL 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
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
  • Y10T428/1266—O, S, or organic compound in metal component
• • Y—GENERAL 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
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
  • Y10T428/12771—Transition metal-base component
  • Y10T428/12806—Refractory [Group IVB, VB, or VIB] metal-base component
  • Y10T428/12826—Group VIB metal-base component
  • Y10T428/12847—Cr-base component
  • Y10T428/12854—Next to Co-, Fe-, or Ni-base component
• • Y—GENERAL 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
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
  • Y10T428/12771—Transition metal-base component
  • Y10T428/12861—Group VIII or IB metal-base component
  • Y10T428/12944—Ni-base component

Definitions

• the solid particles comprise particles of a 204/41 204/49 204/ solid, nonacid-resistant silicate which gives an alkaline reac- [51] int. Cl. ..C23b 5/50, C23C 3/02 tie in aqueous Suspension
• the resulting composite coating [58] Field of Search ..204/38, 38.2, 41, 40, 49, 181; has an outstanding corrosion resistance 10 Claims, No Drawings PROCESS FOR COATING AN OBJECT WITH-ABRIGHT NICKEL/CHROMIUM COATING CROSS-REFERENCES TO RELATED APPLICATIONS
• This application is a continuation-in-part of my copending 5 BACKGROUND OF THE INVENTION AND DESCRIPTION OF THE PRIOR ART It is known to apply a nickel coating to an object from a bath in which are dispersedone or more finely divided solids which are insoluble in the bath, such as silicates, for'example, of aluminum, magnesium
• the resulting nickel coating has a satiny appearance, so that a chromium-layer plated over the nickel coating does not have the brightness required for the majority of uses for nickel/chromium coatings.
• satiny coatings have a great corrosion resistance, which may be attributed to the fact that during the application of the chromium layer no chromium is deposited on the locations where solid particles which are electric nonconductors or poor conductors are present on the surface of the satiny nickel layer, so that a microporous chromium layer is formed. Owing to the presence of numerous micropores in the chromium layer, the greatest possible surface area of the subjacent nickel layer is exposed, so that the corrosion current caused by element action per unit of surface area is minimal.
• the coating owes its high corrosion resistance to the microporous structure of the chromium layer, which is caused by the electrically nonconductive or poorly conductive solid particles originating-from the solid material suspended in the bath fromwhich the intermediate layer is deposited, andwhich are embedded in said intermediate layer.
• the nickel/chromium coating owes its brightness to the fact that the thickness of the intermediate layer containing embedded solid particles is so minute that the brightness of the basic nickel layer is practically not diminished by the intermediate layer.
• the present invention accordingly provides, in a process for coating an object with a bright nickel/chromium coating, comprising the steps of providing an object having thereon a bright nickel coating, applying to said coating an intermediate metal layer containing particles from a plating bath containing said particles in suspension, and plating chromium over said intermediate layer, the improvement wherein said particles comprise particles of a solid, nonacid-resistant silicate which gives an alkaline reaction in aqueous suspension, said silicate being the product of heating a mixture of finely divided diatomaceous earth, a hydroxide of an alkaline earth metal, and water.
• Theimproved corrosion resistance of the nickel/chromium coatingsobtainedfby the process according to the invention is a result of the factthatat the intermediate layer the acid medium which occurs in theelectrochemical corrosion reactions is neutralized by the silicates embedded in said intermediate layer, said silicates being nonacid-resistantand giving an alkaline reaction in water. Accordingly, in addition to the great corrosion resistance caused by the microporous nature of the chromium layer, the electrochemical corrosion reaction itself isadverselyaffected.
• the silicates. to be used according to the invention which have an alkaline reaction in water and are not acid-resistant, are conventionalfilter aids which in addition to the main component; SiO principally contain CaO and/or MgO, and generally'have aspecific gravity of from 2.0-2.8. When heated at 900C. they exhibit a considerable lossdue to calcination. A 20 percent suspension of these silicates in water has a pHof from 7.6 to 10.
• the silicates may be prepared in accordance with theteaching in US. Pat. No. 1,574,363, by heating a mixture of finely divided diatomaceous earth, a hydroxide of an alkaline earth metal, and water, preferably at a temperature of between and C., depending on conditions of pressure and time.
• the quantity of water in the mixture should be enough to contain the swollen product.
• the mixture contains at least 25 parts by weight of water per part by weight. of diatomaceous, earth and at least 5 percent, preferably 30-l00-percent by weight, of CaO or MgO, calculated on the weight of the diatomaceous earth.
• the average particle size of these materials is about l micron.
• the smallest particles are smaller than 0.1 micron.
• the silicate is added to the bath after thepH of the latter has been adjusted to a value of at :least 6.1. for example, by means of NaOH or ammonia.
• the pH of the bath may also be adjusted to such a value by the addition of such. a quantity of the silicate that after the neutralization of the bath a sufficient quantity of unaffected silicate remains.
• dimethyl glyoxime which forms an insoluble compound with nickel ions formed in the corrosion of nickel
• further reducing agents such as hydrazine, which inhibit the anodic iron and/or nickel corrosion
• corrosion inhibitors such as Shell V.P.l. (dicyclohexylamine nitrite), which gives off vapors inhibiting the corrosion of iron.
• Such substances may be dissolved in a suitable medium, for example, alcohol, whereafter the nonacid-resistant silicate having an alkaline reaction in water is impregnated with such solution. After repeated washing, the product is suitable for use in the process according to the invention.
• a suitable medium for example, alcohol
• EXAMPLE 1 Iron covers having a surface area of 1.2 dm. were provided with a bright nickel coating by a treatment for minutes at an average current density of 5 a./dm. and utilizing cathode movement, in the following electrolytic bath:
• EXAMPLE ll Covers provided with a bright nickel coating in the manner described in Example I were provided with an intermediate layer having a thickness of l micron by a treatment for 1 minute, at an average current density of 5 a./dm. in the following baths:
• Cover F had a high brightness throughout its surface and was still without rust after six cycles in the Corrodkote test.
• Cover G had a high brightness and showed 3 percent rust after four cycles in the Corrodkote test.
• Cover H had a high brightness and showed 5 percent rust after four cycles in the Corrodkote test.
• covers were chromi- Temperamreoc' 40 um plated for 1 minute at an average current density of 15 b h f I f I 2 a rig tener, consisting 0 an equimo ar mixture 0 se enium diethyl dithiocarbam the followmg bath mate and tetraethyl thiuram disulfide.
• Cover D had a high brightness and showed 7 percent rust after two cycles in the Corrodkote test.
• EXAMPLE IV Cover E had a high brightness and showed 3 percent rust v v afte'fourcydemthecmdkmetestwi ?ai'ififiniliiafiiffi i'fi'iilfiilifili1E?551K133?
• Cover K had a high brightness and did not show a trace of corrosion after seven cycles in the Corrodkote test.
• Cover L had a high brightness, but showed 5 percent rust after four cycles in the Corrodkote test.
• EXAMPLE v A cover provided with a bright nickel coating in the manner described in Example I was provided with an intermediate layer of a thickness of 0.6 micron by a treatment for 1 minute in the following bath:
• Nickel sulphate g.ll. 300 Nickel chloride. g./l. 60 Boric acid, g.ll. 4S saccharine, g./l. 2 Quinaldine ethyliodide, g./
• a plain iron cover was provided with a bright nickel coating by a treatment in the same bath M for ll minutes at an average current density of 5 a./dm.
• EXAMPLE Vl Covers provided with a bright nickel coating in the manner described in Example l were provided with an intermediate layer having a thickness of 0.75 micron by a treatment for 45 seconds at an average current density of 5 a./dm. in the following baths:
• a process for coating an object with a bright nickel/chromium coating comprising the steps of providing an object having thereon a bright nickel coating, applying to said coating an intermediate metal layer containing particles from a plating bath containing said particles in suspension; and plating chromium over said intermediate layer, the improvement wherein said plating bath has a pH of at least 6.1 and wherein said particles comprise particles of a solid, nonacid-resistant silicate which in the form of a 20 percent suspension in water has a pH of at least 7.6, said silicate being the product of heating a mixture of finely divided diatomaceous earth, a hydroxide of an alkaline earth metal, and water.
• a process according to claim 2, wherein the concentration of said particles in said plating bath is in the range of about 2-20 grams per liter of bath.
• silicate is the product of heating at a temperature between C. and C. a mixture of finely divided diatomaceous earth, a hydroxide of an alkaline earth metal, and water.
• concentration of said particles in said plating bath is at least about 2 grams per liter of bath.
• said corrosion inhibitor is selected from the group consisting of dimethyl glyoxime, hydrazine and dicyclohexylamine nitrite.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Electrochemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• Electroplating And Plating Baths Therefor (AREA)
• Electroplating Methods And Accessories (AREA)
• Other Surface Treatments For Metallic Materials (AREA)
• Chemical Treatment Of Metals (AREA)

Applications Claiming Priority (1)

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Cited By (18)

Families Citing this family (1)

• 0
  • NL NL287612D patent/NL287612A/xx unknown
  • NL NL127557D patent/NL127557C/xx active
• 1964
  • 1964-01-02 GB GB254/64A patent/GB1056222A/en not_active Expired
• 1968
  • 1968-02-19 US US706619A patent/US3644183A/en not_active Expired - Lifetime

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