US3574068A - Process for preparing a metal plate receptive to a decorative metal deposit - Google Patents

Process for preparing a metal plate receptive to a decorative metal deposit Download PDF

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US3574068A
US3574068A US509267A US3574068DA US3574068A US 3574068 A US3574068 A US 3574068A US 509267 A US509267 A US 509267A US 3574068D A US3574068D A US 3574068DA US 3574068 A US3574068 A US 3574068A
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chromium
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Hyman Chessin
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M&T Chemicals Inc
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    • 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

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  • this invention relates to novel compositions and to the process for preparing a metal plate receptive to a decorative noble metal deposit, characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate, which comprises affixing to a basis material bearing a conductive metal surface a stratum of particles having a particle size of about 0.0545 microns and a density on said conductive metal surface of about 1005,000,000 particles/cm.
  • a conductive metal layer having an effective thickness less than the maximum thickness of said stratum of particles thereby forming a matrix wherein said particles are retained affixed to said surface in fixed position in said conductive metal layer, and at least some of said particles intercept the surface of said conductive metal layer.
  • This invention relates to a novel process for preparing a metal plate particularly characterized by its receptivity to noble metal plate, typified by a corrosion-resistant decorative electrodeposited chromium plate containing microcracked areas and microporous areas over substantially the entire surface of said chromium plate.
  • decorative noble metal plate typified by chromium plate may be obtained by e.g. electrodepositing chromium onto a surface of electrodeposited nickel.
  • chromium plate obtained in this manner may be subject to defects including gross cracking or crazing and excessive corrosion which decreases usefulness as decorative chromium.
  • the process of this invention for preparing a metal plate receptive to a decorative noble metal deposit comprises affixing to a basis material bearing a conductive metal surface a stratum of particles having a particle size of about 0.05-15 microns and a density on said conductive metal surface of about 5,000,000 partic1es/cm.
  • a conductive metal layer having an effective thickness less than the maximum thickness of said stratum of particles thereby forming a matrix wherein said particles are retained affixed to said surface in fixed position in said conductive metal layer, and at least some of said particles intercept the surface of said conductive metal layer.
  • the basis material which may be treated according to this invention may include a basis metal such as iron, steel, zinc, or brass which has been first plated with a nickel, etc., either pure or in the form of alloy.
  • the preferred basis metal to be plated in accordance with this invention may be steel, zinc, or brass and most preferably steel, zinc, or brass which has been first plated with a conductive deposit such as a plate of bright nickel, typically preceded by a first plate of copper, bronze, or semi-bright nickel.
  • basis materials which may be treated by the process of this invention may include plastics and resins including acrylonitrile-butadiene-styrene, acetals, acrylics, alkyds, allyls, aminos, cellulosics, chlorinated polyethers, epoxys, furanes, fiuorocarbons, isocyanates (urethanes), polyamides (nylons), phenoxys, phenolics, polycarbonates, polyesters, polyethylenes, polypropylenes, silicones, polystyrenes, polyvinyls, and copolymers, etc. of these materials.
  • the basis material to be treated by process of this invention is a plastic or resin, the surface thereof will be treated as by deposition thereon of a conductive deposit, such as a nickel deposit.
  • the basis material bearing a conductive surface may be immediately treated after disposition of such plate or it may be water rinsed; or it may be rinsed, dipped in aqueous acid solution such as O.5%-10%, say 2%, by weight of sulfuric acid prior to further treatment.
  • aqueous acid solution such as O.5%-10%, say 2%, by weight of sulfuric acid prior to further treatment.
  • the so-treated material may be dried or it may be further treated as is. If drying has been permitted, the conductive surface may be cleaned as by cathodically treating in alkaline cleaner followed by rinsing in water or dipping in an acid solution before further treatment.
  • Nickel plating baths which may be employed in the practice of this invention in forming plate on the surface of the basis material may include various electrodeposition baths. Typical baths may include those indicated below, all values being grams per liter (g./l.), except for the pH which is electrometric.
  • a typical Watts bath which may be used in practice of this invention may include baths containing the following components in aqueous solution:
  • a typical sulfamate-type bath which may be used in practice of the process of this invention may include the following components in aqueous solution:
  • TAB LE II Component Minimum Maximum Preferred Nickel sulfamate 330 400 375 Nickel chloride, hydrated 15 60 45 Boric acid 33 55 45 pH 3 5 4.
  • a typical chloride-free, sulfate-type bath which may be used in practice of the process of this invention may include the following components in aqueous solution:
  • TAB LE III Component Minimum Maximum Preferred Nickel sulfate, hydrated 300 500 400 Boric acid 35 55 45 pH 3 5 4. 0
  • a typical chloride-free, sulfamate-type bath which may be used in practice of the process of this invention may include the following components in aqueous solution:
  • TAB LE IV Component Minimum Maximum Preferred Nickel sulfamate 300 400 350 Boric acid 35 55 45 pH 3 5 4. 0
  • a typical pyrophosphate-type which may be used in practice of the process of this invention may include the following components in aqueous solution:
  • a typical fluoborate-type bath which may be used in the practice of the process of this invention may include the following components in aqueous solution:
  • the plating baths may further contain brighteners or other additives such as sodium saccharate or wetting agents.
  • High-foaming wetting agents such as sodium lauryl sulfate may be particularly useful when employed in conjunction with mechanical agitations; and low-foam ing agents such as sodium dialkylsulfosuccinates may be particularly useful when employed in conjunction with air agitation.
  • the basis material preferably bearing a first plate (of e.g. copper) and a nickel or duplex nickel plate may be further treated by afixing thereto a stratum of particles having a particle size of about 0.05-15 microns.
  • the particles may be finely-divided, naturallyoccurring or artificially prepared materials. They may be spherical, chunky, angular, ovular, elongated, plateletshaped, etc. Preferably they may be flat, i.e. have two dimensions substantially greater than the third dimension.
  • the preferred particles may be platelets.
  • Typical particulate materials which may be employed may include talc; kaolin; wax; graphite; sulfides such as molybdenum disulfide and tungsten disulfide; pigments including barytes, chromium-cobalt green and cobalt-aluminum blue and oxides such as silica and alumina; particles of plastic e.g. polymers or copolymers of styrene, butadiene, acrylonitrile, vinyl acetate, vinyl chloride, etc.; diatomaceous earths; powdered aluminum; activated carbon; silicates e.g. sodium silicate; carbonates, e.g. calcium carbonate; carbides; sulfur; etc., or mixtures of these materials.
  • talc talc
  • kaolin wax
  • graphite sulfides
  • sulfides such as molybdenum disulfide and tungsten disulfide
  • pigments including barytes, chromium
  • additives such as polar organic compounds, e.g. amides, amines, long-chain alcohols, acetylenics, etc., to enhance the properties of adhesion, inhibition, or dispersion.
  • polar organic compounds e.g. amides, amines, long-chain alcohols, acetylenics, etc.
  • Application of particles may be effected by contacting the basis material with particles.
  • the particles may be blown over the surface of the conductive metal surface of the basis material.
  • the basis material may be dipped into a bed, preferably a fluidized bed of particles i.e. particles suspended in an upflowing stream of gas.
  • Afiixing of particles may be effected by electrostatic or electrophoretic techniques on the basis metal piece. If desired, the basis metal may be wet to assist deposition thereon and adherence thereto of the particles.
  • the preferred particles may be used in the form of a bath i.e. a suspension, emulsion, dispersion, or latex of the solid or semi-solid particles in a fluid, preferably a liquid.
  • the particles may be particles of solid suspended in a liquid in concentration as low as 0.001%, typically, 0.1%-2%, and preferably about 0.5%. Outstanding results may be obtained by use of baths containing 0.1%2% particles.
  • the particles in the bath may be from commercially available materials: for example, talc may be. obtained having particles ranging in size up to about 7 microns. 0.0l2% of talc may be added to water and dispersed as by milling in a ball mill or in a Waring Blendor or by stirring. Similar techniques may be employed to disperse wax, pigments, kaolin, etc.
  • the fluid, typically aqueous medium, in which the particles may be suspended may be water, but preferably is a bath having a composition substantially similar to the bath immediately preceding from which the basis material may have been removed after treatment, e.g. a water-rinse bath or a nickel-plating bath.
  • Air, mechanical, or ultrasonic agitation may be used to maintain the particles in suspension.
  • Additives such as suspending agents including surfactants, dispersants, thixotropes, emulsifiers, etc., e.g. alginates, lignosulfonates, gelatin, etc., may be present, and if desired, electrolytes including sodium sulfate, heavy metal salts, acids, etc.
  • the bath When the bath is a latex bath, it may be formed from various resins.
  • Illustrative resins which may be present in latices used in the instant invention include resins containing non-aromatic unsaturation in the repeating unit of the molecule formed from:
  • Diene compositions including butadiene typically natural rubber; isoprene i.e. Z-methyl butadiene; chloroprene i.e. 2-chloro-butadiene; pentadiene-1-3; etc.
  • (-b) Acrylate compositions including acrylate and methacrylate esters such as methyl acrylate; methyl methacrylate; ethyl acrylate; ethyl methacrylate; propyl acrylate; etc.
  • Vinyl compositions including vinyl chloride; vinyl acetate; l-chloro-propene-l; styrene; 0-, m-, and p-methyl styrenes; etc.
  • Olefin compositions including ethylene; propylene; butylene; etc.
  • Typical compositions may include those formed from more than one of the above types, such as from two components including butadiene-styrene; butadiene-acryloniq trile; methyl acrylate-styrene; etc. or three components (terpolymers) including e.g. acrylonitrile-butadiene-styrene; etc. Most preferably polymers of the noted compositions may be used in the form of copolymers with e.g. other noted compositions.
  • compositions may be modified and typically carboxylic-modified i.e. the molecule containing aliphatic unsaturation may be modified by the addition thereto of a carboxylic acid group. Typically this may be effected e.g. by reacting the composition with maleic anhydride in order to form carboxylic groups on the polymer molecule or by hydrolyzing a CN group to a carboxyl group.
  • latices which may be employed in practice of the process of this invention that they may be readily available from natural sources e.g. natural rubber latex or that they may readily be formed by dispersing synthetic compositions in aqueous media, e.g. butadiene-styrene polymer latices.
  • a water-based acrylic polymer latex having a nonionic emulsifier, a pH of 7, and an average particle size of 0.16 micron such as that sold under the trademark Hycar 2601 by B. F. Goodrich Chemical Co.
  • a water-based copolymer of butadiene-styrenecarboxylic modified latex i.e. a latex wherein butadienestyrene copolymer is modified by the inclusion of COOH groups
  • a synthetic emulsifier i.e. a pH of 9, and an average particle size of 0.16 micron (such as that sold under the trademark Pliolite 491 by Goodyear Industrial Products Co.);
  • a water-based hydrocarbon resin latex having a nonionic emulsifier, a pH of 8.8 and a maximum particle size of 1 micron such as that solid under the trademark Piccopale N-3 by Pennsylvania Industrial Chemical Corporation
  • a water-based vinyl acetate polymer latex having a non-ionic emulsifier, a pH of 4.0-5.5, and an average particle size of about 1 micron such as that sold under the trademark Plyamul 40-370 by Reichhold Chemical Co.
  • a Water-based vinyl acetate polymer latex having an anionic emulsifier, a pH of 3.5-5.5, and an average particle size of 0.5 micron such as that sold under the trademark Gelva T S-30 by Shawinigan Resins Corp.
  • micron such as that sold under the trademark Dow 700 by Dow Chemical Co.
  • a Water-based vinyl acetate polymer latex having a pH of 4.0-5.0, an anionic emulsifier, and a particle size of 005-3 microns (such as that sold under the trademark CL-102 by Celanese Corp. of America);
  • the preferred latices may be in the form of nonconductive latices in aqueous medium, typically containing -60%, say resin in the aqueous medium. Commonly these latices may be characterized by the presence of colloidal-size particles, typically less than about one micron and commonly of the order of 0.0005-0.2 micron.
  • the most highly preferred latices which may be used in practice of this invention to permit attainment of the preferred chromium plate containing microcracked areas and microporous areas over substantially the entire area of the chromium plate include the carboxylic-modified butadiene copolymer latices containing particles of an average size of up to about 1 micron.
  • latices Typical of such latices is (b) supra sold under the trademark Pliolite 491 in which the average particle size may be about 0.16 micron.
  • Other latices may include vinylidene chloride copolymer latices such as the copolymer with acrylonitrile, as (i) supra sold under the trademark Saran Latex F122 A15 in which the average particle size may be about 0.2 micron.
  • a preferred latex may for example be a polyvinyl chloride latex containing 0.5% by weight of polyvinyl chloride having a nominal particle size about 0.16 micron, such as that sold under the trademark Dow 700 (g) supra). Additives including dispersants etc. may be present.
  • the particles may be employed in the form of an aqueous dispersion having the following composition:
  • a preferred bath in the form of a dispersion which may be employed may include:
  • Application of the particles onto the metal surface may preferably be eifected by dipping the metal surface in an aqueous bath containing said particles. Dipping may be effected, preferably at ambient temperature of 10 C.-40 C., and the surface may be retained therein for time sufficient to inundate the surface, typically 5-60 seconds, preferably about 30 seconds. Moderate agitation in this step may be preferred.
  • the surface may then be removed from the bath bearing a stratum of particles which cling evenly distributed thereonprobably held in place by surface tension and adsorptive forces.
  • the particles may be affixed to the surface of these forces and may be uniformly distributed thereover.
  • the surface so-attained may, if desired, be allowed to dry, or it may be water-washed, or it may be further processed as is e.g. bearing a thin film of adherent liquor.
  • the surface bearing the stratum of afiixed particles may then be further treated.
  • a conductive layer having an effective thickness less than the maximum thickness of the stratum of particles whereby a high portion of the upper surfaces of the particles remain uncovered.
  • the surface may be immersed in a plating bath, preferably an electroplating bath wherein a conductive metal layer may be deposited.
  • the conductive layer may typically be of nickel, nickel-tin, cobalt, silver, rhodium, platinum, copper, bronze, brass, zinc, cadmium, manganese, etc.; the preferred metal may be nickel. It is preferred that these baths be continuously filtered, and when necessary, treated with active carbon to prevent buildup of impurities and insolubles.
  • nickel may be deposited from any of the baths hereinbefore noted. Plating may be carried out at 15 C.-60 C., say 54 C.
  • the average cathode current density may typically be 1.0-15 amperes per square decimeter (a.s.d.), preferably 5 a.s.d.
  • the temperature s,574,0as When the pyrophosphate bath supra is used, the temperature s,574,0as
  • Plating may typically be carried out to produce a conductive layer preferably having an effective thickness less than the maximum thickness of the stratum of particles whereby said particles are retained in fixed position in the conductive layer and at least some of said particles penetrate the surface of the layer.
  • the effective thickness may average 0.02-3 microns, preferably 0.2 micron.
  • a matrix of particles in a conductive layer of metal i.e. a heterogeneous matrix deposit. Microscopic inspection of the matrix deposit may readily reveal that the particles may be retained in fixed position in a matrix of the conductive layer. It will also be observed (as by dark field illumination in a microscope or by the Dubpernell test) that the particles may traverse the conductive layer and may be observed above the upper surfaces thereof.
  • the conductive layer is deposited in effective thickness less than the maximum thickness of the stratum of particles, there may be formed a matrix wherein the particles aflixed to the metal surface are retained in fixed position in the conductive layer and at least some of the particles intercept the surface of the conductive layer.
  • the particles in the conductive layer are substantially spherical particles having more-or-less uniform size, the resulting matrix cross-section may appear to be essentially as set forth in FIG. 1 of the drawing.
  • the effective thickness of the conductive layer may be 50% 60% of the thickness of the stratum of particles and the particles more-Or-less uniformly intercept the surface of the conductive layer in which they are retained in fixed position.
  • FIG. 2 there is shown a typical illustrative crosssection through the surface of a conductive layer having an effective thickness less than the maximum thickness of the stratum of particles.
  • the particles are heterogeneously sized; as Will be apparent, varying proportions of different sized particles intercept the surface of the conductive layer in which the particles are retained in position.
  • FIG. 3 is shown a typical cross-section of a matrix formed by first aflixing a plurality of flat platelets of heterogeneous size to the basis metal and thereafter depositing a conductive layer in the stratum.
  • the effective thickness of the conductive layer is less than the actual thickness of the stratum of particles, i.e. in spite of the bridging effect, the upper portion or surface of at least some of the platelet particles is not covered by the deposited conductive layer.
  • the actual thickness of the conductive layer may be greater than the actual thickness of the stratum by as much as half the average width of the typical platelet particle.
  • the.actual thickness of the conductive layer which yields an effective thickness less than the maximum thickness of the stratum of particles may vary from typically about 20%-30% of the thickness of the stratum to as much as 200% of the thickness of the stratum.
  • the actual thickness of the conductive layer may be as little as 20%.
  • the actual thickness of the conductive layer may be 50%60%.
  • the actual thickness of the conductive layer may be 50%200% or more typically 100% of the maximum thickness of the stratum of particles.
  • the effective thickness of the conductive layer is less than the maximum thickness of the stratum of particles, i.e. the conductive layer forms a matrix wherein the particles of said stratum are retained in fixed position in the conductive layer and at least some of said particles traverse the conductive layer :and intercept or penetrate the surface of said conductive layer.
  • the particles in the matrix remain afiixed to and :appear to be in contact with the metal surface of the basis material.
  • the product so-prepared may typically thus include :a metal plate (receptive to a noble metal plate, such as :a decorative chromium plate, characterized by the presence of microporous or microcracked areas over sub- :stantially the entire surface of said chromium plate) comprising a basis material bearing a conductive metal surface, and atfixed thereto -5,000,000 particles/emi each particle having a size of about 0.0545 microns, said particles being fixed in a matrix containing a conductive metal layer, at least some of said particles traversing said conductive metal layer and intercepting the surface thereof.
  • a metal plate receptive to a noble metal plate, such as :a decorative chromium plate, characterized by the presence of microporous or microcracked areas over sub- :stantially the entire surface of said chromium plate
  • a basis material bearing a conductive metal surface and atfixed thereto -5,000,000 particles/emi each particle having a size of about 0.0545 micro
  • Chromium plating may be effected at temperature of 30-60 C., -.say 43 C., and current density of 5-50 a.s.d., say 10 a.s.d., for 05-15 minutes, say 5 minutes, from a bath containing 100-500 g./l., say 250 g./l., of chromic acid and 1-5 g./l., say 2.5 g./l. of sulfate ion, typically derived from sodium sulfate.
  • Other components including other chromium plating catalysts, e.g. fluoride or silicofiuoride, self-regulating strontium ion-containing compositions, fume suppressants, etc. may be present in the chromium plating bath.
  • the chromium plate prepared by the process of this invention may be obtained in thickness of at least 0.02 micron, typically in decorative thickness of less than about 1 micron, and may be further particularly characterized by its bright decorative appearance, its high corrosion- :resistance, and by its microcracked and microporous structure.
  • the chromium plate, which lies over the matrix plate containing particles which may partially protrude above or intercept the surface of the conductive layer, may possess microcracking and microporosity over substantially the entire area of its surface.
  • the microcracked surface area of the chromium plate prepared by the process of this invention may be found to have at least 100 microcracks per linear centimeter at 40 mm. from the high current density end of a standard Hull cell panel plated with 10 amperes for 5 minutes at 43 0, compared to 5-10 microcracks per inch for the same chromium on the typical prior art nickel plate.
  • This unexpectedly high degree of microcracking is sufficient to obtain microcracked areas over all thicknesses of chromium plated in the high and intermediate current density areas.
  • the high degree of microcracking extends sufficiently over the surface of the chromium plate so as to be essentially contiguous with the microporous areas which are characteristic of the low current density areas of the chromium plate on the matrix surface.
  • This product may be inspected under a microscope and found to contain a microporous surface in the low current density areas of the standard Hull cell panel. Typically it may possess a plurality of pores, typically about one hundred to tWo or three million (at a chromium thickness of less than about 0.5 micron), more-or-less uniformly distributed over the surface of the metal. Chromium deposited, on eg a nickel plate, prepared by the process of this invention may thus be found to contain microporous areas or microcracked areas over the entire surface. Because of the presence, over all areas of the chomium plate, of microperforated areas (i.e. either microporous areas or microcracked areas), it is possible to attain the novel benefits herein set forth.
  • the cracking of a chromium plate will depend on its thickness. Such factors as concentration of chromic acid, concentration of 0.5 micron. The degree of microcracking (attained at catalyst materials, temperature of plating, etc.; all have thickness greater than about 0.5 micron) over a typical an effect.
  • chromium dematrix nickel plate may be at least 100 microcracks per posits generally that no cracking appears throughout the li ti t n first Stage of deposition, P to about micfon- AS the 5
  • gross crackmg may a bright nickel plate in a standard commercial bright develop
  • the undeslrable third stage e.g., about 1.0- nickel plating bath
  • the bright nickebplauad panel was 1.5 microns, spangle-type cracking, i.e., microcracking interspersed in gross cracking, may develop.
  • stages two and three may be (1). water rinsed, (2) dipped into 2% by weight sulfuric acid, (3) water rinsed, and thereafter (4) dipped into a dispersion bath containing the suspended particles desigo'bjectionable in appearance in the as-plated condition Hated Tflble
  • the basls metal Plate was and particularly so after the initiation of corrosion has tamed 1n thls bath for about 30 seconds to form thereon emphasized the presence of the cracks.
  • Micropores and a Stratum of Particles, removed and PasSed to a microcracks are not objectionable because the fineness of matrix bath wherein a conductive layer of bright nickel structure is not perceived by the eye except with aid of Plate Was deposited thereofl- The nickel Plating bath magnification. Furthermore the presence of these micro- (treated fI'OIIl time to time active carbon and filtered perforations over the entire plate, permits attainment of to maintain the solution free of impurities and insolubles) the outstanding corrosion-resistant properties hereinafter Contained 300 g. of nickel sulfate heptahydrate, 60 g. of set forth. nickel chloride hexahydrate, 45 g. of boric acid, and
  • Table VI'II sets forth the dispersant, details of operation no objectionable gross cracking or spangle. and results.
  • the footnotes to Table VII and Table VIII The preferred thickness of the bright decorative elecindicate variations in the standard procedure.
  • the foottroplated chromium plate may be 0.025.0 microns, say notes follow Table VIII.
  • tivated carbon 1. 0 do 1. 0 do 1. 0 Chromiumcobalt pigment. 1. 0 0.5 maximum. do 1.0 ....do o. Cobalt-aluminum pigment. 1. 0 V-3285- -do D0. do 1.0 V-3285... do Do. 30 WSz powder-l-Cr-Co pigment 1. 0 SubmicronWS2 andV-7687.-. Bemol, Inc. and Ferro Corp 0.4 (W82) and 0.5 maximum (Cr-Co). 31 do 1.0 do do Do.
  • Example 8 From Examples 1-38, it will be apparent that the novel process permits attainment of unexpected results.
  • Example 8 For example by comparison of Example 8 with control Example 9, it will be observed that the product chromium plate prepared in practice of this invention exhibits 16,- 000 pores per square centimeter, while the control exhibited no pores. It is entirely unexpected that a chromi- 11m plate having a thickness of 0.065 micron would have this degree of rnicroporosity; a normal commercial or prior art chromium plate of this thickness deposited over a bright nickel plate would exhibit a microporosity of essentially zero.
  • a microporous chromium deposit is characterized by substantially improved corrosion resistance.
  • Example 13 it may be possible to produce a chromium deposit of 0.5 micron thickness which is characterized by the presence of 400 microcracks per centimeter-the control Example 16 (typical of a normal prior art plate) exhibited 10 gross cracks per centimeter and no microcracks.
  • a chromium plate characterized by the presence of at least about 100 microcracks per centimeter possesses substantially improved corrosion resistance.
  • Hull cell panels may be bright nickel plated, water rinsed, acid dipped, water rinsed, as were the panels for the first series of examples supra.
  • the panels may then be dipped into an aqueous dispersion of talc (Mistron Monomix brand supplied by Sierra Talc and Chemicals Inc.) having a maximum particle size of 6 microns and a median particle size of 1 micron.
  • talc Magnetic Monomix brand supplied by Sierra Talc and Chemicals Inc.
  • the basis metal, removed from the dispersion, and bearing a stratum of talc was then plated for 10 seconds in a standard commercially available bright nickel system. Current density (C.D.) at varying points on the cathode was determined.
  • the matrix nickel plate containing talc particles was then withdrawn from the bright nickel plating bath, water rinsed, and chromium plated for 60 seconds in a standard chromium plating bath containing 240 g./l. of chromium acid, 1.5 g./l. of sulfate (supplied as sodium sulfate), anld)2 g./l. of silicofluoride SiFF (supplied as the sodium sat).
  • a standard chromium plating bath containing 240 g./l. of chromium acid, 1.5 g./l. of sulfate (supplied as sodium sulfate), anld)2 g./l. of silicofluoride SiFF (supplied as the sodium sat).
  • Example 39 Example 40 was conducted in a manner similar to Example 39, except that the basis metal bearing the stratum of particles was rinsed after the dip in the dispersion.
  • Example 42 there was added to the dispersant 0.0012% of Hallcomid M-l8-01 (80% N,N- dimethyloleamide), C. P. Hall Co. of Illinois.
  • Example 43 the procedure of Example 39 was followed except that no matrix deposit was applied over the stratum of particles, this example thus serving as a control.
  • Steel panels were copper plated and buffed to produce a final layer of buffed copper of about 7.5 microns thick. They were then plated in a bright nickel plating bath to produce a thickness of 25 microns. Except for the control which was Water rinsed and plated in chromium, the others were dipped in the noted dispersion, plated in a matrix bath of Watts nickel for 10 seconds at 3 a.s.d and then plated in chromium. After 48 hours corrosion testing (CASS) the ratings were noted.
  • CSS corrosion testing
  • the CASS rating is given as a pair of numbers wherein the first number indicates the degree of basis metal corrosion and the second number indicates the appearance. In each case, over a scale of to 10, the higher numbers indicate a better rating; and values greater than 7-8 may be acceptable.
  • the control row which is illustrative of the range of thicknesses occurring over a normal decorative plate, is unsatisfactory because over the 0.125 and 0.25 micron areas the corrosion ratings are 2/2 and 3/3 which are unacceptable. At the 0.50 micron thickness, the undesirable gross cracking attained makes the plate unsatisfactory. In contrast, in the other two examples, the micro-perforations permit attainment of satisfactory plate at all thicknesses over the plated piece.
  • a process for preparing a metal plate receptive to a decorative noble metal electrodeposit characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate, comprising affixing to a basis material hearing a conductive metal surface a stratum of particles having a particle size of about 0.05-15 microns and a density on said conductive metal surface of about 100- 5,000,000 particles/cm. and then depositing in said stratum of particles a conductive metal layer free of said particles having an effective thickness less than the maximum thickness of said stratum of particles thereby forming a matrix wherein said particles are retained affixed to said surface in fixed position in said conductive metal layer, and at least some of said particles intercept the surface of said conductive metal layer.
  • a process for preparing a metal plate receptive to a decorative noble metal electrodeposit characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 1 wherein said conductive metal surface is a nickel surface.
  • a process for preparing a metal plate receptive to a decorative noble metal electrodeposit characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 1 wherein said density of said particles is 5,000-2,000,000 particles/cm? 4.
  • a process for preparing a metal plate receptive to a decorative noble metal electrodeposit characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 1 wherein said particles are platelet-shaped.
  • a process for preparing a metal plate receptive to a decorative noble metal electrodeposit characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 1 wherein said particles are affixed to said conductive metal surface from a bath.
  • a process for preparing a metal plate receptive to a decorative noble metal electrodeposit characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 1 wherein said particles are affixed to said conductive metal surface by dipping said basis material into a fluidized bed of said particles.
  • a process for preparing a metal plate receptive to a decorative noble metal electrodeposit characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 1 wherein said particles are particulate material selected from the group consisting of talc, kaolin, wax, graphite, sulfide, pigments, plastics, diatomaceous earths, powdered aluminum, activated carbon, silicates, carbonates, carbides, sulfur, and mixtures of these materials.
  • a process for preparing a metal plate receptive to a decorative noble metal electrodeposit characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 7 wherein said particulate material is talc.
  • a 'process for preparing a metal plate receptive to a decorative noble metal electrodeposit characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 7 wherein said particulate material is graphite.
  • a process for preparing a metal plate receptive to a decorative noble metal electrodeposit characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 7 wherein said particulate material is molybdenum disulfide.
  • a process for preparing a metal plate receptive to a decorative noble metal electrodeposit characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 7 wherein said particulate material is tungsten disulfide.
  • a process for preparing a metal plate receptive to a decorative noble metal electrodeposit characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble 15 metal plate as claimed in claim 7 wherein said particulate material is latex plastic.
  • a process for preparing a metal plate receptive to a decorative noble metal electrodeposit characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 12 wherein said latex plastic is selected from the group consisting of butadiene-styrene copolymer, vinyl chloride polymer, vinyl acetate polymer and vinylidene chloride-acrylonitrile copolymer.
  • a process for preparing a metal plate receptive to a decorative noble metal electrodeposit characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 12 whereinv said latex plastic is acrylonitrile-butadiene-styrene terpolymer.
  • a process for preparing a metal plate receptive to a decorative noble metal electrodeposit characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimedin claim '1 wherein said conductive metal layer is selected from the group consisting of nickel, nickel-tin, cobalt, silver, rhodium, platinum, copper, bronze, brass, zinc, cadmium and manganese.
  • a process for preparing a metal plate receptive to a decorative noble metal electrodeposit characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 15 wherein said conductive metal layer is nickel.
  • a process for preparing a metal plate receptive to a decorative noble metal electrodeposit characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 1 wherein said efiective thickness of said conductive metal layer is 0.02-3 micron;
  • a process for preparing a metal plate receptive to a decorative noble metal electrodeposit characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 1 wherein the actual thickness of said conductive metal layer is 20%200% of the maximum thickness of said stratum of particles whereby said effective thickness of said conductive metal layer is less than said maximum thickness of said stratum of particles.
  • a process for preparing a metal plate receptive to a decorative noble metal electrodeposit characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 1 comprising affixing to a basis material bearing a conductive nickel surface a stratum of latex plastic particleshaving a particle size of about 0.05-15 microns and a density of said conductive nickel surface of about 5,0002,000,000 particles/cm.
  • a process for preparing a decorative electrodeposited chromium plate characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said chromium plate, comprising afiixing to a basis material bearing a conductive metal surface a stratum of particles having a particle size of about 0.05-15 microns and a density on said conductive metal surface of about 1005,000,000 particles/cm.
  • a conductive metal layer free of said particles having an effective thickness less than the maximum thickness of said stratum of particles thereby forming a matrix wherein said particles are retained affixed to said surface in fixed position in said conductive metal layer, and at least some of said particles intercept the surface of said conductive metal layer; and electrodepositing on said matrix a decorative chromium plate whereby said chromium plate contains microporous areas and microcracked areas over substantially its entire surface.

Abstract

IN ACCORDANCE WITH CERTAIN OF ITS ASPECTS, THIS INVENTION RELATES TO NOVEL COMPOSITIONS AND TO THE PROCESS FOR PREPARING A METAL PLATE RECEPTIVE TO A DECORATIVE NOBLE METAL DEPOSIT, CHARACTERIZED BY THE PRESENCE OF MICROPOROUS AREAS AND MICROCRACKED AREAS OVER SUBSTANTIALLY THE ENTIRE SURFACE OF SAID NOBLE METAL PLATE, WHICH COMPRISES AFFIXING TO A BASIS MATERIAL BEARING A CONDUCTIVE METAL SURFACE A STRATUM OF PARTICLES HAVING A PARTICLE SIZE OF ABOUT 0.05-15 MICRONS AND A DENSITY ON SAID CONDUCTIVE METAL

SURFACE OF ABOUT 100-5,000,000 PARTICLES/CM.2, AND DEPOSITING IN SAID STRATUM OF PARTICLES A CONDUCTIVE METAL LAYER HAVING AN EFFECTIVE THICKNESS LESS THAN THE MAXIMUM THICKNESS OF SAID STRATUM OF PARTICLES THEREBY FORMING A MATRIX WHEREIN SAID PARTICLES ARE RETAINED AFFIXED TO SAID SURFACE IN FIXED POSITION IN SAID CONDUCTIVE METAL LAYER, AND AT LEAST SOME OF SAID PARTICLES INTERCEPT THE SURFACE OF SAID CONDUCTIVE METAL LAYER.

Description

Apnl 6, 1971 H. CHESSIN- 3,574,068
' PROCESS FOR PREPARING A METAL PLATE RECEPTIVE T0 A DECORATIVE METAL DEPOSIT v -Fi1ed Nov. 23, 1965 INVIZNTUR.
H YMA/v CHESS/N BY C424 6. JEUTTER AI'I'OQA/E) United States Patent US. Cl. 20416 20 Claims ABSTRACT OF THE DISCLOSURE In accordance with certain of its aspects, this invention relates to novel compositions and to the process for preparing a metal plate receptive to a decorative noble metal deposit, characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate, which comprises affixing to a basis material bearing a conductive metal surface a stratum of particles having a particle size of about 0.0545 microns and a density on said conductive metal surface of about 1005,000,000 particles/cm. and depositing in said stratum of particles a conductive metal layer having an effective thickness less than the maximum thickness of said stratum of particles thereby forming a matrix wherein said particles are retained affixed to said surface in fixed position in said conductive metal layer, and at least some of said particles intercept the surface of said conductive metal layer.
This invention relates to a novel process for preparing a metal plate particularly characterized by its receptivity to noble metal plate, typified by a corrosion-resistant decorative electrodeposited chromium plate containing microcracked areas and microporous areas over substantially the entire surface of said chromium plate.
As is well known to those skilled in the art, decorative noble metal plate typified by chromium plate may be obtained by e.g. electrodepositing chromium onto a surface of electrodeposited nickel. However chromium plate obtained in this manner may be subject to defects including gross cracking or crazing and excessive corrosion which decreases usefulness as decorative chromium.
Prior art processes have attempted to overcome the problem of gross cracking in chromium plate by including in the nickel plating bath (from which may be deposited the nickel undercoat for the chromium plate) a substance which produces a microporous condition in the chromium plate subsequently deposited.
However prior art methods have not succeeded, by employing additives in the nickel plating bath, in preventing gross cracking over all areas of the subsequently deposited chromium plate and thus it has not been possible to attain a chromium plate characterized by the presence of microcracked areas and microporous areas over substantially the entire surface of said chromium plate.
It is an object of this invention to permit attainment of a plate particularly characterized by its receptivity to a noble metal plate typically a decorative chromium plate. It is a further object of this invention to provide a chromium plate which is highly useful as a decorative chromium plate, and which contains microcracked areas and microporous areas over substantially the entire surface area of said chromium plate. Other objects will be apparent to those skilled in the art from inspection of the following description.
"ice
In accordance with certain of its aspects, the process of this invention for preparing a metal plate receptive to a decorative noble metal deposit, characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate, comprises affixing to a basis material bearing a conductive metal surface a stratum of particles having a particle size of about 0.05-15 microns and a density on said conductive metal surface of about 5,000,000 partic1es/cm. and depositing in said stratum of particles a conductive metal layer having an effective thickness less than the maximum thickness of said stratum of particles thereby forming a matrix wherein said particles are retained affixed to said surface in fixed position in said conductive metal layer, and at least some of said particles intercept the surface of said conductive metal layer.
The basis material which may be treated according to this invention may include a basis metal such as iron, steel, zinc, or brass which has been first plated with a nickel, etc., either pure or in the form of alloy. The preferred basis metal to be plated in accordance with this invention may be steel, zinc, or brass and most preferably steel, zinc, or brass which has been first plated with a conductive deposit such as a plate of bright nickel, typically preceded by a first plate of copper, bronze, or semi-bright nickel.
Other basis materials which may be treated by the process of this invention may include plastics and resins including acrylonitrile-butadiene-styrene, acetals, acrylics, alkyds, allyls, aminos, cellulosics, chlorinated polyethers, epoxys, furanes, fiuorocarbons, isocyanates (urethanes), polyamides (nylons), phenoxys, phenolics, polycarbonates, polyesters, polyethylenes, polypropylenes, silicones, polystyrenes, polyvinyls, and copolymers, etc. of these materials. When the basis material to be treated by process of this invention is a plastic or resin, the surface thereof will be treated as by deposition thereon of a conductive deposit, such as a nickel deposit.
The basis material bearing a conductive surface, preferably a bright nickel plate, may be immediately treated after disposition of such plate or it may be water rinsed; or it may be rinsed, dipped in aqueous acid solution such as O.5%-10%, say 2%, by weight of sulfuric acid prior to further treatment. The so-treated material may be dried or it may be further treated as is. If drying has been permitted, the conductive surface may be cleaned as by cathodically treating in alkaline cleaner followed by rinsing in water or dipping in an acid solution before further treatment.
Nickel plating baths which may be employed in the practice of this invention in forming plate on the surface of the basis material may include various electrodeposition baths. Typical baths may include those indicated below, all values being grams per liter (g./l.), except for the pH which is electrometric.
A typical Watts bath which may be used in practice of this invention may include baths containing the following components in aqueous solution:
A typical sulfamate-type bath which may be used in practice of the process of this invention may include the following components in aqueous solution:
TAB LE II Component Minimum Maximum Preferred Nickel sulfamate 330 400 375 Nickel chloride, hydrated 15 60 45 Boric acid 33 55 45 pH 3 5 4.
A typical chloride-free, sulfate-type bath which may be used in practice of the process of this invention may include the following components in aqueous solution:
TAB LE III Component Minimum Maximum Preferred Nickel sulfate, hydrated 300 500 400 Boric acid 35 55 45 pH 3 5 4. 0
A typical chloride-free, sulfamate-type bath which may be used in practice of the process of this invention may include the following components in aqueous solution:
TAB LE IV Component Minimum Maximum Preferred Nickel sulfamate 300 400 350 Boric acid 35 55 45 pH 3 5 4. 0
A typical pyrophosphate-type which may be used in practice of the process of this invention may include the following components in aqueous solution:
A typical fluoborate-type bath which may be used in the practice of the process of this invention may include the following components in aqueous solution:
TABLE VI Component Minimum Maximum Preferred Nickel fiuoborate, hydrated- 250 400 300 Nickel chloride, hydrated.-. 15 60 30 Boric acid 15 30 20 pH 2 4 3. 0
It will be apparent that the above baths may contain components in amounts falling outside the preferred minima and maxima set forth, but that most satisfactory and economical operation may normally be effected when the components are present in the baths in the amounts indicated.
The plating baths may further contain brighteners or other additives such as sodium saccharate or wetting agents. High-foaming wetting agents such as sodium lauryl sulfate may be particularly useful when employed in conjunction with mechanical agitations; and low-foam ing agents such as sodium dialkylsulfosuccinates may be particularly useful when employed in conjunction with air agitation.
In practice of this invention, the basis material preferably bearing a first plate (of e.g. copper) and a nickel or duplex nickel plate, may be further treated by afixing thereto a stratum of particles having a particle size of about 0.05-15 microns.
Typically the particles may be finely-divided, naturallyoccurring or artificially prepared materials. They may be spherical, chunky, angular, ovular, elongated, plateletshaped, etc. Preferably they may be flat, i.e. have two dimensions substantially greater than the third dimension. The preferred particles may be platelets.
Typical particulate materials which may be employed may include talc; kaolin; wax; graphite; sulfides such as molybdenum disulfide and tungsten disulfide; pigments including barytes, chromium-cobalt green and cobalt-aluminum blue and oxides such as silica and alumina; particles of plastic e.g. polymers or copolymers of styrene, butadiene, acrylonitrile, vinyl acetate, vinyl chloride, etc.; diatomaceous earths; powdered aluminum; activated carbon; silicates e.g. sodium silicate; carbonates, e.g. calcium carbonate; carbides; sulfur; etc., or mixtures of these materials.
There may also be present other additives such as polar organic compounds, e.g. amides, amines, long-chain alcohols, acetylenics, etc., to enhance the properties of adhesion, inhibition, or dispersion.
Application of particles may be effected by contacting the basis material with particles. The particles may be blown over the surface of the conductive metal surface of the basis material. The basis material may be dipped into a bed, preferably a fluidized bed of particles i.e. particles suspended in an upflowing stream of gas. Afiixing of particles may be effected by electrostatic or electrophoretic techniques on the basis metal piece. If desired, the basis metal may be wet to assist deposition thereon and adherence thereto of the particles.
The preferred particles may be used in the form of a bath i.e. a suspension, emulsion, dispersion, or latex of the solid or semi-solid particles in a fluid, preferably a liquid. In one preferred embodiment, the particles may be particles of solid suspended in a liquid in concentration as low as 0.001%, typically, 0.1%-2%, and preferably about 0.5%. Outstanding results may be obtained by use of baths containing 0.1%2% particles.
Typically the particles in the bath may be from commercially available materials: for example, talc may be. obtained having particles ranging in size up to about 7 microns. 0.0l2% of talc may be added to water and dispersed as by milling in a ball mill or in a Waring Blendor or by stirring. Similar techniques may be employed to disperse wax, pigments, kaolin, etc.
The fluid, typically aqueous medium, in which the particles may be suspended may be water, but preferably is a bath having a composition substantially similar to the bath immediately preceding from which the basis material may have been removed after treatment, e.g. a water-rinse bath or a nickel-plating bath.
Air, mechanical, or ultrasonic agitation may be used to maintain the particles in suspension. Additives such as suspending agents including surfactants, dispersants, thixotropes, emulsifiers, etc., e.g. alginates, lignosulfonates, gelatin, etc., may be present, and if desired, electrolytes including sodium sulfate, heavy metal salts, acids, etc.
When the bath is a latex bath, it may be formed from various resins. Illustrative resins which may be present in latices used in the instant invention include resins containing non-aromatic unsaturation in the repeating unit of the molecule formed from:
(a) Diene compositions including butadiene typically natural rubber; isoprene i.e. Z-methyl butadiene; chloroprene i.e. 2-chloro-butadiene; pentadiene-1-3; etc.
(-b) Acrylate compositions including acrylate and methacrylate esters such as methyl acrylate; methyl methacrylate; ethyl acrylate; ethyl methacrylate; propyl acrylate; etc.
(o) Acrylonitrile compositions including acrylonitrile; methacrylonitrile; ethacrylonitrile; etc.
((1) Vinyl compositions including vinyl chloride; vinyl acetate; l-chloro-propene-l; styrene; 0-, m-, and p-methyl styrenes; etc.
(e) Olefin compositions including ethylene; propylene; butylene; etc.
Typical compositions may include those formed from more than one of the above types, such as from two components including butadiene-styrene; butadiene-acryloniq trile; methyl acrylate-styrene; etc. or three components (terpolymers) including e.g. acrylonitrile-butadiene-styrene; etc. Most preferably polymers of the noted compositions may be used in the form of copolymers with e.g. other noted compositions.
The above compositions may be modified and typically carboxylic-modified i.e. the molecule containing aliphatic unsaturation may be modified by the addition thereto of a carboxylic acid group. Typically this may be effected e.g. by reacting the composition with maleic anhydride in order to form carboxylic groups on the polymer molecule or by hydrolyzing a CN group to a carboxyl group.
It is a feature of the latices which may be employed in practice of the process of this invention that they may be readily available from natural sources e.g. natural rubber latex or that they may readily be formed by dispersing synthetic compositions in aqueous media, e.g. butadiene-styrene polymer latices.
Illustrative specific commercially available synthetic latices which may be used in practice of this invention include:
(a) A water-based acrylic polymer latex having a nonionic emulsifier, a pH of 7, and an average particle size of 0.16 micron (such as that sold under the trademark Hycar 2601 by B. F. Goodrich Chemical Co.);
(b) A water-based copolymer of butadiene-styrenecarboxylic modified latex (i.e. a latex wherein butadienestyrene copolymer is modified by the inclusion of COOH groups), including a synthetic emulsifier, a pH of 9, and an average particle size of 0.16 micron (such as that sold under the trademark Pliolite 491 by Goodyear Industrial Products Co.);
(c) A water-based hydrocarbon resin latex having a nonionic emulsifier, a pH of 8.8 and a maximum particle size of 1 micron (such as that solid under the trademark Piccopale N-3 by Pennsylvania Industrial Chemical Corporation);
(d) A water-based vinyl acetate polymer latex having a non-ionic emulsifier, a pH of 4.0-5.5, and an average particle size of about 1 micron (such as that sold under the trademark Plyamul 40-370 by Reichhold Chemical Co.);
(e) A Water-based vinyl acetate polymer latex having an anionic emulsifier, a pH of 3.5-5.5, and an average particle size of 0.5 micron (such as that sold under the trademark Gelva T S-30 by Shawinigan Resins Corp.);
(f) A. water-based copolymer of butadiene-styrene 50/50 latex having a synthetic emulsifier, a pH of 9.6, a non-staining anti-oxidant, and an average particle size of 0.6 micron (such as that sold under the trademark Pliolite 176 by Goodyear Industrial Products Co.);
(g) A water-based vinyl chloride polymer latex having a pH of 8.0, and an average particle size of 0.16
micron (such as that sold under the trademark Dow 700 by Dow Chemical Co.);
(h) A Water-based vinyl acetate polymer latex having a pH of 4.0-5.0, an anionic emulsifier, and a particle size of 005-3 microns (such as that sold under the trademark CL-102 by Celanese Corp. of America);
(i) A water-based copolymer of vinylidene chloride acrylonitrile 85/15 latex having an anionic emulsifier; a pH of 6.0/7.0, and an average particle size of 0.2 micron (such as that solid under the trademark Saran Latex F122 A by Dow Chemical Co.);
The preferred latices may be in the form of nonconductive latices in aqueous medium, typically containing -60%, say resin in the aqueous medium. Commonly these latices may be characterized by the presence of colloidal-size particles, typically less than about one micron and commonly of the order of 0.0005-0.2 micron. The most highly preferred latices which may be used in practice of this invention to permit attainment of the preferred chromium plate containing microcracked areas and microporous areas over substantially the entire area of the chromium plate include the carboxylic-modified butadiene copolymer latices containing particles of an average size of up to about 1 micron. Typical of such latices is (b) supra sold under the trademark Pliolite 491 in which the average particle size may be about 0.16 micron. Other latices may include vinylidene chloride copolymer latices such as the copolymer with acrylonitrile, as (i) supra sold under the trademark Saran Latex F122 A15 in which the average particle size may be about 0.2 micron. A preferred latex may for example be a polyvinyl chloride latex containing 0.5% by weight of polyvinyl chloride having a nominal particle size about 0.16 micron, such as that sold under the trademark Dow 700 (g) supra). Additives including dispersants etc. may be present.
Typically the particles may be employed in the form of an aqueous dispersion having the following composition:
Parts by weight Minimum Maximum Preferred A preferred bath in the form of a dispersion which may be employed may include:
Parts by weight Application of the particles onto the metal surface may preferably be eifected by dipping the metal surface in an aqueous bath containing said particles. Dipping may be effected, preferably at ambient temperature of 10 C.-40 C., and the surface may be retained therein for time sufficient to inundate the surface, typically 5-60 seconds, preferably about 30 seconds. Moderate agitation in this step may be preferred.
The surface may then be removed from the bath bearing a stratum of particles which cling evenly distributed thereonprobably held in place by surface tension and adsorptive forces. The particles may be affixed to the surface of these forces and may be uniformly distributed thereover. Typically there may be 100-5,000,000 particles on each square centimeter of surface, and commonly 5,000-2,000,000 particles/cm? The surface so-attained may, if desired, be allowed to dry, or it may be water-washed, or it may be further processed as is e.g. bearing a thin film of adherent liquor.
The surface bearing the stratum of afiixed particles may then be further treated. There may be deposited on said surface and in said stratum, a conductive layer having an effective thickness less than the maximum thickness of the stratum of particles whereby a high portion of the upper surfaces of the particles remain uncovered. The surface may be immersed in a plating bath, preferably an electroplating bath wherein a conductive metal layer may be deposited. The conductive layer may typically be of nickel, nickel-tin, cobalt, silver, rhodium, platinum, copper, bronze, brass, zinc, cadmium, manganese, etc.; the preferred metal may be nickel. It is preferred that these baths be continuously filtered, and when necessary, treated with active carbon to prevent buildup of impurities and insolubles.
In the preferred embodiment, nickel may be deposited from any of the baths hereinbefore noted. Plating may be carried out at 15 C.-60 C., say 54 C. The average cathode current density may typically be 1.0-15 amperes per square decimeter (a.s.d.), preferably 5 a.s.d. When the pyrophosphate bath supra is used, the temperature s,574,0as
may typically be C.-35 C. and the cathode current density 0.2-2 a.s.d.
Plating may typically be carried out to produce a conductive layer preferably having an effective thickness less than the maximum thickness of the stratum of particles whereby said particles are retained in fixed position in the conductive layer and at least some of said particles penetrate the surface of the layer. Typically the effective thickness may average 0.02-3 microns, preferably 0.2 micron. There will thus be formed a matrix of particles in a conductive layer of metal, i.e. a heterogeneous matrix deposit. Microscopic inspection of the matrix deposit may readily reveal that the particles may be retained in fixed position in a matrix of the conductive layer. It will also be observed (as by dark field illumination in a microscope or by the Dubpernell test) that the particles may traverse the conductive layer and may be observed above the upper surfaces thereof.
Inspection of the stratum of particles in which the conductive layer has been deposited will clearly indicate that when the conductive layer is deposited in effective thickness less than the maximum thickness of the stratum of particles, there may be formed a matrix wherein the particles aflixed to the metal surface are retained in fixed position in the conductive layer and at least some of the particles intercept the surface of the conductive layer. When the particles in the conductive layer are substantially spherical particles having more-or-less uniform size, the resulting matrix cross-section may appear to be essentially as set forth in FIG. 1 of the drawing. Here the effective thickness of the conductive layer may be 50% 60% of the thickness of the stratum of particles and the particles more-Or-less uniformly intercept the surface of the conductive layer in which they are retained in fixed position.
In FIG. 2, there is shown a typical illustrative crosssection through the surface of a conductive layer having an effective thickness less than the maximum thickness of the stratum of particles. In this FIG. 2, the particles are heterogeneously sized; as Will be apparent, varying proportions of different sized particles intercept the surface of the conductive layer in which the particles are retained in position.
In FIG. 3, is shown a typical cross-section of a matrix formed by first aflixing a plurality of flat platelets of heterogeneous size to the basis metal and thereafter depositing a conductive layer in the stratum. As will be apparent from inspection of this FIG. 3, the effective thickness of the conductive layer is less than the actual thickness of the stratum of particles, i.e. in spite of the bridging effect, the upper portion or surface of at least some of the platelet particles is not covered by the deposited conductive layer. It will be noted however that the actual thickness of the conductive layer may be greater than the actual thickness of the stratum by as much as half the average width of the typical platelet particle.
Typically the.actual thickness of the conductive layer which yields an effective thickness less than the maximum thickness of the stratum of particles may vary from typically about 20%-30% of the thickness of the stratum to as much as 200% of the thickness of the stratum. For example, when the particles are irregular or highly porous, the actual thickness of the conductive layer may be as little as 20%. When the particles are substantially spherical and uniformly sized, the actual thickness of the conductive layer may be 50%60%. When the particles are heterogeneously sized platelets, the actual thickness of the conductive layer may be 50%200% or more typically 100% of the maximum thickness of the stratum of particles.
Under each of these conditions, the effective thickness of the conductive layer is less than the maximum thickness of the stratum of particles, i.e. the conductive layer forms a matrix wherein the particles of said stratum are retained in fixed position in the conductive layer and at least some of said particles traverse the conductive layer :and intercept or penetrate the surface of said conductive layer. In each of these embodiments, it will be observed :that the particles in the matrix remain afiixed to and :appear to be in contact with the metal surface of the basis material.
The product so-prepared may typically thus include :a metal plate (receptive to a noble metal plate, such as :a decorative chromium plate, characterized by the presence of microporous or microcracked areas over sub- :stantially the entire surface of said chromium plate) comprising a basis material bearing a conductive metal surface, and atfixed thereto -5,000,000 particles/emi each particle having a size of about 0.0545 microns, said particles being fixed in a matrix containing a conductive metal layer, at least some of said particles traversing said conductive metal layer and intercepting the surface thereof.
The basis metal plated with matrix plate, as hereinabove set forth, may then be further plated with a decorative noble metal deposit, typically chromium. Chromium plating may be effected at temperature of 30-60 C., -.say 43 C., and current density of 5-50 a.s.d., say 10 a.s.d., for 05-15 minutes, say 5 minutes, from a bath containing 100-500 g./l., say 250 g./l., of chromic acid and 1-5 g./l., say 2.5 g./l. of sulfate ion, typically derived from sodium sulfate. Other components including other chromium plating catalysts, e.g. fluoride or silicofiuoride, self-regulating strontium ion-containing compositions, fume suppressants, etc. may be present in the chromium plating bath.
The chromium plate prepared by the process of this invention may be obtained in thickness of at least 0.02 micron, typically in decorative thickness of less than about 1 micron, and may be further particularly characterized by its bright decorative appearance, its high corrosion- :resistance, and by its microcracked and microporous structure. The chromium plate, which lies over the matrix plate containing particles which may partially protrude above or intercept the surface of the conductive layer, may possess microcracking and microporosity over substantially the entire area of its surface.
The microcracked surface area of the chromium plate prepared by the process of this invention may be found to have at least 100 microcracks per linear centimeter at 40 mm. from the high current density end of a standard Hull cell panel plated with 10 amperes for 5 minutes at 43 0, compared to 5-10 microcracks per inch for the same chromium on the typical prior art nickel plate. This unexpectedly high degree of microcracking is sufficient to obtain microcracked areas over all thicknesses of chromium plated in the high and intermediate current density areas. The high degree of microcracking extends sufficiently over the surface of the chromium plate so as to be essentially contiguous with the microporous areas which are characteristic of the low current density areas of the chromium plate on the matrix surface.
This product may be inspected under a microscope and found to contain a microporous surface in the low current density areas of the standard Hull cell panel. Typically it may possess a plurality of pores, typically about one hundred to tWo or three million (at a chromium thickness of less than about 0.5 micron), more-or-less uniformly distributed over the surface of the metal. Chromium deposited, on eg a nickel plate, prepared by the process of this invention may thus be found to contain microporous areas or microcracked areas over the entire surface. Because of the presence, over all areas of the chomium plate, of microperforated areas (i.e. either microporous areas or microcracked areas), it is possible to attain the novel benefits herein set forth.
When chromium plating is applied .to the heterogeneous matrix-stratum described herein unexpected benefits are derived. Other factors being constant, the cracking of a chromium plate will depend on its thickness. Such factors as concentration of chromic acid, concentration of 0.5 micron. The degree of microcracking (attained at catalyst materials, temperature of plating, etc.; all have thickness greater than about 0.5 micron) over a typical an effect. It is characteristic of prior art chromium dematrix nickel plate may be at least 100 microcracks per posits generally that no cracking appears throughout the li ti t n first Stage of deposition, P to about micfon- AS the 5 In the following series of examples, unless otherwise thickness is increased in the undesirable second stage, ifi ll noted, basis meta] panels were plated with h range of mlcron, gross crackmg may a bright nickel plate in a standard commercial bright develop; 1n the undeslrable third stage, e.g., about 1.0- nickel plating bath The bright nickebplauad panel was 1.5 microns, spangle-type cracking, i.e., microcracking interspersed in gross cracking, may develop. In the fourth stage, microcracking alone may develop. The undesirable intermediate stages, i.e., stages two and three, may be (1). water rinsed, (2) dipped into 2% by weight sulfuric acid, (3) water rinsed, and thereafter (4) dipped into a dispersion bath containing the suspended particles desigo'bjectionable in appearance in the as-plated condition Hated Tflble The basls metal Plate was and particularly so after the initiation of corrosion has tamed 1n thls bath for about 30 seconds to form thereon emphasized the presence of the cracks. Micropores and a Stratum of Particles, removed and PasSed to a microcracks are not objectionable because the fineness of matrix bath wherein a conductive layer of bright nickel structure is not perceived by the eye except with aid of Plate Was deposited thereofl- The nickel Plating bath magnification. Furthermore the presence of these micro- (treated fI'OIIl time to time active carbon and filtered perforations over the entire plate, permits attainment of to maintain the solution free of impurities and insolubles) the outstanding corrosion-resistant properties hereinafter Contained 300 g. of nickel sulfate heptahydrate, 60 g. of set forth. nickel chloride hexahydrate, 45 g. of boric acid, and
It has been unexpectedly found in the practice of this Water to Blake up P "P invention that microporosity is produced in stage one After mckel Platmg, Panel was rinsed with and microcracking is facilitated so that the undesirable W and then Chromlum Plated in a bath Containstages two and three Le gross and spangle type cracking, 20 mg 250 g./l. of chromic acid, 2.5 g./l. of sulfate (added do not appear. Thus a final plated chromium part may as Sodlum Sulfate) at 430 have microporosity where low current densities occur Table VII sets forth the dispersed material employed. and microcracking in higher current density areas with Table VI'II sets forth the dispersant, details of operation no objectionable gross cracking or spangle. and results. The footnotes to Table VII and Table VIII The preferred thickness of the bright decorative elecindicate variations in the standard procedure. The foottroplated chromium plate may be 0.025.0 microns, say notes follow Table VIII.
TABLE VII Percent Designation of Nominal particle Example Type of dispersed material (w./w.) dispersed material Supplier size (microns) 1 gatexiiolyvinyl chloride 0. 5 Dow 700 Dow Chemical Co 0.16. 2 on o 2".-- gatetx-piolyvinyl acetate. 0. 027 Plyamul -370 Reichhold Chemical Inc 0.5 to 2.0.
1 on re 5 3 Latex-polyvinyl acetate 0. 027 Plyamul 40-370 Reichhpld Chemical Inc- 0.5 to 2.0 6 do 0. Gelva 'IS-30. Sliawinlgan Plastics Corp .5. 7 do 0. 55 Shawimgan Resins Corp. O 5. 8 Latex-styrene/butadiene- 0. 024 Firestone Plastics Co- 0 2 9 4 Control 10 MOS; powder 1. 0 Consolidated Astronautics Incl 11 WSz powder 1.0 Bemol, Ine 0.4. 12 d 1. 0 do 0.4. 13 Talc- 0. 8 Sierra Talc & Chem 0.4 to 6 maximum. 14 do 0.8 do Do. 15 do 0. 8 0 Do.
16 4 Control 17 Graphite 1. 0 10 to 12 maximum.
d 1. 0 Do. do 1. 0 4.2 maximum. .do 0.1 2t0 5.
do- 0. 4 Do. do 1. 6 Do.
tivated carbon 1. 0 do 1. 0 do 1. 0 Chromiumcobalt pigment. 1. 0 0.5 maximum. do 1.0 ....do o. Cobalt-aluminum pigment. 1. 0 V-3285- -do D0. do 1.0 V-3285... do Do. 30 WSz powder-l-Cr-Co pigment 1. 0 SubmicronWS2 andV-7687.-. Bemol, Inc. and Ferro Corp 0.4 (W82) and 0.5 maximum (Cr-Co). 31 do 1.0 do do Do.
1. Aldosterse 00-200 Glyco Chem. Inc
...' 1.0 to 6 maximum.
. D Do. 0.4 do.. do Do. 0. 2 Camel-Wh1te Harry T. Campbell Sons Corp. 10 maximum. 0. 03 Prepared by pouring hot, saturated alcohol solution of sulfur into water 1 N o dip in dispersion.
3 Directly to chromium plate from basis nickel plate.
2 Eliminate steps (1), (2), and (3) in standard sequence. 4 Directly to chromium plate from basis nickel plate.
TABLE VIII Matrix bath Chromium Bath Number of Chromium Aqueous phase Time CD Time C.D Number of microcracks thickness, Example (dispersant) (sec.) (a.s.d.) (sec.) (a.s.d.) pores/em! per cm. microns 1 Electrolyte like 60 0. 65 6O 3. 25 5, 000 0. 032
matrix. 2 60 3. 25 0.032 3 Electrolyte like 180 4. 0 60 20 7, 000 0. 20
matrix. I 4 Z 60 20 0. 20 5 3 Electrolyte like 180 4. 0 60 0. 20
matrix.
4. 0 60 20 0. 20 1. 3 60 6. 5 0. 065 1. 3 60 6. 5 0. 065 60 6. 5 0. 065 1. 3 60 6.5 0. 065 7. 0 60 0. 35 2. 0 60 10 0. 10 10 60 0. 50 7. 0 35 0. 35 l. 3 60 6. 5 0. 065 60 50 0. 50 7. 0 60 35 O. 035 2. 9 60 14. 5 0. 014 5. 2 60 26 0. 026 4. 8 120 15. 5 0. 31 4. 8 120 15. 5 0. 31 4. 8 120 15. 5 0. 31 7 60 35 0. 35 4 60 20 0. 20 3 60 15 0. 15 10 60 50 0. 5O 5. 2 60 26 0. 26 10 60 50 0. 50 5. 2 60 26 0. 26 10 60 50 0. 50 5. 2 60 26 0. 26 7.0 60 35 0. 35 4. 8 120 15. 5 0. 31 4. 8 240 15. 5 0. 62 4. 8 480 15. 5 1. 24; 4. 8 120 15. 5 0. 31 2. 2 6O 14. 5 0. 145 5. 2 60 76 0. 76
1 No dip in dipersion.
a Directly to chromium plate from basis nickel plate.
2 Eliminate steps (1), (2), and (3) in standard sequence. 4 Directly to chromium plate from basis nickel plate.
From Examples 1-38, it will be apparent that the novel process permits attainment of unexpected results. For example by comparison of Example 8 with control Example 9, it will be observed that the product chromium plate prepared in practice of this invention exhibits 16,- 000 pores per square centimeter, while the control exhibited no pores. It is entirely unexpected that a chromi- 11m plate having a thickness of 0.065 micron would have this degree of rnicroporosity; a normal commercial or prior art chromium plate of this thickness deposited over a bright nickel plate would exhibit a microporosity of essentially zero. A microporous chromium deposit is characterized by substantially improved corrosion resistance.
It will also be apparent, from a comparison of Example 13 with control Example 16 that it may be possible to produce a chromium deposit of 0.5 micron thickness which is characterized by the presence of 400 microcracks per centimeter-the control Example 16 (typical of a normal prior art plate) exhibited 10 gross cracks per centimeter and no microcracks. A chromium plate characterized by the presence of at least about 100 microcracks per centimeter possesses substantially improved corrosion resistance.
In the following examples, Hull cell panels may be bright nickel plated, water rinsed, acid dipped, water rinsed, as were the panels for the first series of examples supra. The panels may then be dipped into an aqueous dispersion of talc (Mistron Monomix brand supplied by Sierra Talc and Chemicals Inc.) having a maximum particle size of 6 microns and a median particle size of 1 micron. The basis metal, removed from the dispersion, and bearing a stratum of talc was then plated for 10 seconds in a standard commercially available bright nickel system. Current density (C.D.) at varying points on the cathode was determined.
The matrix nickel plate containing talc particles was then withdrawn from the bright nickel plating bath, water rinsed, and chromium plated for 60 seconds in a standard chromium plating bath containing 240 g./l. of chromium acid, 1.5 g./l. of sulfate (supplied as sodium sulfate), anld)2 g./l. of silicofluoride SiFF (supplied as the sodium sat The product chromium plate was observed and the number of microcracks/ cm. or the number of pores/cm? was determined by standard techniques.
In Table IX infra, the noted procedure was followed for Example 39. Example 40 was conducted in a manner similar to Example 39, except that the basis metal bearing the stratum of particles was rinsed after the dip in the dispersion. In Example 42, there was added to the dispersant 0.0012% of Hallcomid M-l8-01 (80% N,N- dimethyloleamide), C. P. Hall Co. of Illinois. In Example 43, the procedure of Example 39 was followed except that no matrix deposit was applied over the stratum of particles, this example thus serving as a control. l
TABLE IX Cone. 0.1). in N1 C.D.inCr
tale, matrix bath, bath, g./l. a.s.d. a.s.d.
Thousand pores/om.
n- H H H Jwcno wem o NnhQO M c-10 From Table D(, it will be apparent that practice of the process of this invention permits attainment of product chromium plate characterized by microcracking in desired amount at selected thickness and by microporosity at selected thickness. More significantly, Table IX shows that it is possible to plate an entire panel over a wide range of current densities and to obtain a chromium plate which, at all normal decorative thicknesses, possesses either a desired microcrack pattern or a desired microporosity. This continuity of microcracking and microporosity permits attainment, over the entire area, of a chromium plate having an unexpectedly high resistance to corrosion. In practice prior art processes, if the plater tries to produce microcracking over the entire area of a decorative chromium plate, there are produced plated areas (e.g. intermediate current density areas) which are neither microcracked nor microporous, but rather are undesirably characterized by gross cracking with attendant low corrosion resistance and poor appearance.
The following examples serve to illustrate the advantages in corrosion resistance obtained by practice of this invention.
Steel panels were copper plated and buffed to produce a final layer of buffed copper of about 7.5 microns thick. They were then plated in a bright nickel plating bath to produce a thickness of 25 microns. Except for the control which was Water rinsed and plated in chromium, the others were dipped in the noted dispersion, plated in a matrix bath of Watts nickel for 10 seconds at 3 a.s.d and then plated in chromium. After 48 hours corrosion testing (CASS) the ratings were noted.
In Table X, the CASS rating is given as a pair of numbers wherein the first number indicates the degree of basis metal corrosion and the second number indicates the appearance. In each case, over a scale of to 10, the higher numbers indicate a better rating; and values greater than 7-8 may be acceptable. Thus the control row, which is illustrative of the range of thicknesses occurring over a normal decorative plate, is unsatisfactory because over the 0.125 and 0.25 micron areas the corrosion ratings are 2/2 and 3/3 which are unacceptable. At the 0.50 micron thickness, the undesirable gross cracking attained makes the plate unsatisfactory. In contrast, in the other two examples, the micro-perforations permit attainment of satisfactory plate at all thicknesses over the plated piece.
Although this invention has been illustrated by reference to specific examples, numerous changes and modifications thereof which clearly fall within the scope of the invention will be apparent to those skilled in the art.
I claim:
1. A process for preparing a metal plate receptive to a decorative noble metal electrodeposit, characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate, comprising affixing to a basis material hearing a conductive metal surface a stratum of particles having a particle size of about 0.05-15 microns and a density on said conductive metal surface of about 100- 5,000,000 particles/cm. and then depositing in said stratum of particles a conductive metal layer free of said particles having an effective thickness less than the maximum thickness of said stratum of particles thereby forming a matrix wherein said particles are retained affixed to said surface in fixed position in said conductive metal layer, and at least some of said particles intercept the surface of said conductive metal layer.
2. A process for preparing a metal plate receptive to a decorative noble metal electrodeposit, characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 1 wherein said conductive metal surface is a nickel surface.
3. A process for preparing a metal plate receptive to a decorative noble metal electrodeposit, characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 1 wherein said density of said particles is 5,000-2,000,000 particles/cm? 4. A process for preparing a metal plate receptive to a decorative noble metal electrodeposit, characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 1 wherein said particles are platelet-shaped.
5. A process for preparing a metal plate receptive to a decorative noble metal electrodeposit, characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 1 wherein said particles are affixed to said conductive metal surface from a bath.
6. A process for preparing a metal plate receptive to a decorative noble metal electrodeposit, characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 1 wherein said particles are affixed to said conductive metal surface by dipping said basis material into a fluidized bed of said particles.
7. A process for preparing a metal plate receptive to a decorative noble metal electrodeposit, characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 1 wherein said particles are particulate material selected from the group consisting of talc, kaolin, wax, graphite, sulfide, pigments, plastics, diatomaceous earths, powdered aluminum, activated carbon, silicates, carbonates, carbides, sulfur, and mixtures of these materials.
8. A process for preparing a metal plate receptive to a decorative noble metal electrodeposit, characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 7 wherein said particulate material is talc.
9. A 'process for preparing a metal plate receptive to a decorative noble metal electrodeposit, characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 7 wherein said particulate material is graphite.
10. A process for preparing a metal plate receptive to a decorative noble metal electrodeposit, characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 7 wherein said particulate material is molybdenum disulfide.
11. A process for preparing a metal plate receptive to a decorative noble metal electrodeposit, characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 7 wherein said particulate material is tungsten disulfide.
12. A process for preparing a metal plate receptive to a decorative noble metal electrodeposit, characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble 15 metal plate as claimed in claim 7 wherein said particulate material is latex plastic. 1
13. A process for preparing a metal plate receptive to a decorative noble metal electrodeposit, characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 12 wherein said latex plastic is selected from the group consisting of butadiene-styrene copolymer, vinyl chloride polymer, vinyl acetate polymer and vinylidene chloride-acrylonitrile copolymer.
14. A process for preparing a metal plate receptive to a decorative noble metal electrodeposit, characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 12 whereinv said latex plastic is acrylonitrile-butadiene-styrene terpolymer.
15. A process for preparing a metal plate receptive to a decorative noble metal electrodeposit, characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimedin claim '1 wherein said conductive metal layer is selected from the group consisting of nickel, nickel-tin, cobalt, silver, rhodium, platinum, copper, bronze, brass, zinc, cadmium and manganese.
16. A process for preparing a metal plate receptive to a decorative noble metal electrodeposit, characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 15 wherein said conductive metal layer is nickel.
17. A process for preparing a metal plate receptive to a decorative noble metal electrodeposit, characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 1 wherein said efiective thickness of said conductive metal layer is 0.02-3 micron;
18. A process for preparing a metal plate receptive to a decorative noble metal electrodeposit, characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 1 wherein the actual thickness of said conductive metal layer is 20%200% of the maximum thickness of said stratum of particles whereby said effective thickness of said conductive metal layer is less than said maximum thickness of said stratum of particles.
19. A process for preparing a metal plate receptive to a decorative noble metal electrodeposit, characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said noble metal plate as claimed in claim 1 comprising affixing to a basis material bearing a conductive nickel surface a stratum of latex plastic particleshaving a particle size of about 0.05-15 microns and a density of said conductive nickel surface of about 5,0002,000,000 particles/cm. and then depositing in said stratum of latex plastic particles a conductive nickel layer free of said particles having an effective thickness of 0.02-3 microns, which effecttive thickness is less than the maximum thickness of said stratum of latex plastic particles thereby forming a matrix wherein said latex plastic particles are retained affixed to said surface in fixed position in said conductive layer, and at least some of said particles intercept the surface of said conductive nickel layer.
20. A process for preparing a decorative electrodeposited chromium plate characterized by the presence of microporous areas and microcracked areas over substantially the entire surface of said chromium plate, comprising afiixing to a basis material bearing a conductive metal surface a stratum of particles having a particle size of about 0.05-15 microns and a density on said conductive metal surface of about 1005,000,000 particles/cm. then depositing in said stratum of particles a conductive metal layer free of said particles having an effective thickness less than the maximum thickness of said stratum of particles thereby forming a matrix wherein said particles are retained affixed to said surface in fixed position in said conductive metal layer, and at least some of said particles intercept the surface of said conductive metal layer; and electrodepositing on said matrix a decorative chromium plate whereby said chromium plate contains microporous areas and microcracked areas over substantially its entire surface.
References Cited UNITED STATES PATENTS JOHN H. MACK, Primary Examiner T. TUFARIELLO, Assistant Examiner US. Cl. X.R. (20438, 41
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WO2003027353A1 (en) * 2001-09-17 2003-04-03 Infineon Technologies Ag Method for production of a metal layer on a support body and support body with a metal layer

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003027353A1 (en) * 2001-09-17 2003-04-03 Infineon Technologies Ag Method for production of a metal layer on a support body and support body with a metal layer
US20050052326A1 (en) * 2001-09-17 2005-03-10 Infineon Technologies Ag Process for producing a metal layer on a substrate body, and substrate body having a metal layer
US6984446B2 (en) 2001-09-17 2006-01-10 Infineon Technologies Ag Process for producing a metal layer on a substrate body, and substrate body having a metal layer

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