Classifications

• • 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
  • 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
  • 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
  • Y10T428/12493—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.]
  • Y10T428/1266—O, S, or organic compound in metal component
  • Y10T428/12667—Oxide of transition metal or Al
• • 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

• This invention relates to a method for covering objects with a decorative bright nickel/chromium coating having excellent corrosion resistance and the products produced by the method.
• a method for coating an object with a bright nickel coating comprising the step of electroplating said object with nickel from a bright nickel electroplating bath containing bath insoluble solid particles therein to produce on said object a bright nickel coating containing solid particles therein, said particles having a conductivity not exceeding the conductivity of graphite, the concentration of said solid particles in said bright nickel plating bath not exceeding, in grams per liter of liquid bath, 20 d/s., b being the average diameter of said particles in microns, and s being the specific gravity of said particles.
• This bright nickel coating having particles therein is then plated with chromium to produce a highly corrosion resistant bright nickel/chromium coating.
• the invention is further directed to certain preferred operating conditions, as Well as the resultant products.
• a thin intermediate layer containing particles is. deposited between the bright nickel layer and the chromium layer, and a bare structure of more than 50% bare surface is achieved, however, on the condition, that the intermediate layer does not become too thick, or, in other words, that the galvanic intermediate treatment will not last too long, as in that case the nickel/chromium coating would turn dull.
• the intermediate layer of Patent No. 3,298,802 is eliminated, with the particles being incorporated into the base bright nickel layer.
• the bright nickel plating bath Prior to the present invention it was generally accepted that in order to obtain bright nickel coatings and to avoid any dulling of the coating, the bright nickel plating bath had to be very carefully filtered to remove all particles therefrom. However, it has been surprisingly found that, under the proper conditions, it is possible to produce highly bright nickel coatings from bright nickel plating baths having solid particles therein. High brightness can even be obtained from entirely cloudy electrolyte baths. The coatings obtained from such bright nickel plating baths having particles therein are highly bright nickel coatings having particles embedded therein.
• the most significant and the controlling factors which are involved in obtaining the bright nickel coating from particle containing bright nickel baths are: (1) The concentration of the solid particles; (2) The size (diameter) of the particles; (3) The specific gravity of the particles.
• the size (diameter) of the particles The dulling effect on the nickel coating increases as the size of the particles decreases. For example, if using two baths of the same concentration of particles having the same particles therein with the particles of one bath having a diameter of 0.05 micron and the particles of the other bath having the diameter of 1 micron, the dulling effect of nickel plating will be far greater in the case of the bath having particles whose diameter is 0.05 micron. In the case of particles having a size of 1 micron, a multiple of a concentration of the particles can be used before obtaining the same dulling eitect as would be produced when using particles of 0.05 micron. In this application, both in the specification and in the claims, when referring to particles which occur in a flat or plate-like form, such as aluminum oxide, it is taken for their diameter the diameter of a sphere having the same volume as the plate.
• the specific gravity of the particles plays a part insofar that, using particles with a higher specific gravity, a greater concentration may be applied with respect to the rate of the dulling effect.
• the nature of the particles also plays a certain part, such, that in applying transparent materials (glass powder, quartz powder and diamond powder, etc.) the concentration may be slightly higher than is the case with substances like aluminum oxide, titanium oxide, filtering earth, iron oxide, chromium oxide or molybdenum oxide. Where the size of the particles is the same, at most twice as much may be added of the transparent materials as of the non-transparent solid substances.
• d is the average diameter of the solid particles in microns
• s is the specific gravity of the particles
• c is the concentration of the particles in the plating bath expressed in grams per liter of liquid bath.
• the nickel plated from such bright nickel plating bath will be a bright nickel layer having particles embedded therein.
• the loss of brightness can be avoided by increasing the current density, or by increasing the amount of conventional brightening agent in the bath, such as butynediol, propargyl alcohol, chinaldine-ethyliodide, etc.
• an optimal brightness can be obtained in all cases, even under unfavorable conditions, when the concentration of particles is about 25% of the maximum permitted. In other words, even under unfavorable circumstances, satisfactory brightness can be obtained with a good open chromium coating when the concentration 0 of the particles does not exceed 5 d./s.
• concentration c of the particles should not be less d.s. in order to obtain desired corrosion resistance together with the brightness.
• concentration c of the particles should not be less d.s. in order to obtain desired corrosion resistance together with the brightness.
• concentration c of the particles should not be less d.s. in order to obtain desired corrosion resistance together with the brightness.
• a concentration c should be between about d./s. and 10 d./s., and a preferred concentration should be about 5 d./s.
• Quartz powder- 1 2. 6 52 12. 5 MOS 0.05 4.8 4.8 1.25 0. 3 3. 5 21 5. 25 0.2 2. 6 10. 4 2. 5 0. 3 7. 3 43. 8 l1 2 2. 5 25 0. 4 5. 2 41. 6 10. 5 0. 3 5. 2 31. 2 7. 5 0. 2 2. 6 10. 4 2. 5 1 3. 1 62 15 0. 05 1. 8 1. 8 0. 45 O. 1 4. 5 9 2. 25 0. 1 4. 1 8. 2 2
• Nickel sulfate NiSO '6H O
• Nickel chloride NiCl -6H O
• Boric acid H BO 40 Saccharine 1 2 Butyne2-diol-1,4 (HOH2CCE-CH2OH)
• Chromic oxide Cr O 300 Sulphuric acid (H 50 3 at a temperature of 40 C. and with a current density of 15 A./d.m.
• the pattern of the open pores is developed by copperplating in an acid copper bath to render the pores more readily visible.
• a microscopic examination with a magnification of at least 300 times it is found that approximately 20% of the surface will lie bare.
• the aluminum oxide has the following sieve anaylis:
• the average particle size d is calculated as follows:
• nickel hydroxide is added until 4 grams of nickel hydroxide per liter of bath liquid have been precipitated.
• the suspension of nickel hydroxide is kept in motion by means of a stirrer.
• the average diameter of the nickel hydroxide particles is 0.1 micron.
• the particles can be added to any standard bright nickel plating bath. It is possible to add the particles to any other normal type of nickel plating bath, even those not producing a bright plate and obtain resistance to corrosion, but the essence of the invention is not only to produce resistance to corrosion, but to obtain a bright finish which, according to the prior art, was hitherto considered unobtainable.
• EXAMPLE 3 This example compares the brightness and corrosion resistance produced according to the invention with that obtained from plating baths outside the scope of the invention.
• a number of iron covers were plated with a nickel layer 10 microns thick, using the following baths and then the nickel was subsequently overplated with chromium from a standard chromium plating bath. The following baths were used:
• the barium sulphate had an average diameter of 0.1 micron and a specific gravity of 4.5, the kaolin an average diameter of 0.1 micron and a specific gravity of 2.6, and the calcium carbonate an average diameter of 0.05 micron and a specific gravity of 1.8.
• Coatings A, B C and D all show a uniform high brightness. Of these layers, A represents a control, since no particles were used in bath A. Coatings B C and D are within the scope of the present invention, while the remaining ones are outside the invention. Covers B and C showed a uniform satiny lustre.
• the brightness of the resulting plating is substantially the same 'as that which would have been produced by utilizing the same bath without the particles, but the utilization of the particles Within the ranges of the invention produced a corrosion resistance significantly greater than that which the plating has when produced in the absence of particles.
• the particles as used in the present invention serve to produce the corrosion resistance of the chromium plate.
• nickel When nickel is plated from a bath containing particles, some of the particles become embedded in the nickel layer as the latter is formed, and also cover part of the surface thereof. Since the solid particles are nonconductive, or semi-conductive, no nickel will be deposited on these particles, so that pores will be formed in the nickel layer, which may be closed again during further formation of the nickel layer. Accordingly, the surface of the ultimate nickel layer will show pores "and non-conductive or semi-conductive particles on which no chromium is deposited during the subsequent chromium plating, so that a microporous chromium layer is formed, the porosity or openness of the chromium layer imparting the corrosion resistance.
• the number of particles which are embedded in a nickel layer depend primarily upon the particles concentration in the nickel bath. Obviously, if there is a high cencentration, relatively more particles will be embedded in the nickel layer which will produce a uniformly light diffusing layer. As the concentration of the particles is lowered, normally it would be thought that the embedding of particles would be non-uniform (caused by various factors, such as locally varying current density and/or non-homogeneous distribution of the particles in the bath), and therefore a smoky or non-uniform coating would be produced and these are the results predicted by the above mentioned three patents.
• concentration range for solid particles there is a concentration range for solid particles, said concentration range being intermediate zero concentration and the concentration range which produces a smoky appearance, at which the solid particles are embedded in the layer in sufiicient amount to produce corrosion resistance and at the same time, without affecting the brightness of the layer.
• the controlling factors are the specific gravity and the particle size and it is not necessary to consider the number of particles in the bath as a separate factor. In fact, the number of particles is not a separate factor, but inherently is defined by the specific gravity and the particle volume in conjunction with the concentration. The particle volume can be calculated from the particle diameter.
• the diameter of the particles used in the present invention fall within the range of colloidal up to about 10 microns.
• the size of the particles should not exceed about 5 microns.
• These figures refer to the diameters of substantially each particle used.
• the average particle diameter should not exceed about 2 microns, and preferably the average diameter should not exceed about 1 micron, the optimum average particle diameter should be about 0.1-0.5 micron.
• a method for coating an object with a bright nickel/ chromium coating comprising the steps of electroplating said object with nickel from a bright nickel electroplating bath containing bath insoluble solid particles therein to produce on said object a bright nickel coating containing solid particles therein, said particles having a conductivity not exceeding the conductivity of graphite, the concentration of said solid particles in said bright nickel plating bath not exceeding, in grams per liter of liquid bath, 20 d./s., d being the average diameter of said particles in microns, and s being the specific gravity of said particles, and then electroplating chromium over said bright nickel coating containing solid particles therein, the concentration of said particles being at least d./s.
• the particles are selected from the class consisting of quartz powder, MoS, A1 0 China Clay, CeO B C,, Fe O Cr O glass powder, SiC, CaCo BaSO and Ni(OH) References Cited UNITED STATES PATENTS 3,061,525 10/ 1962 Grazen 204-9 3,152,971 1 0/1964 Tomaszewski et al. 204-41 3,152,972 10/1964 'Brown et a1 204-41 3,152,973 10/1-964 Tomaszewski et a1. 204-41 HOWARD S. WILLIAMS, Primary Examiner.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Electroplating And Plating Baths Therefor (AREA)
• Electroplating Methods And Accessories (AREA)

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Cited By (16)

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• 0
  • NL NL123689D patent/NL123689C/xx active
  • NL NL279109D patent/NL279109A/xx unknown
• 1963
  • 1963-04-19 GB GB15559/63A patent/GB1042355A/en not_active Expired
  • 1963-05-24 DE DE1963N0023216 patent/DE1496928A1/de active Pending
  • 1963-05-29 SE SE5932/63A patent/SE313476B/xx unknown
• 1967
  • 1967-07-06 US US651381A patent/US3449223A/en not_active Expired - Lifetime

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