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
  • C25D5/34—Pretreatment of metallic surfaces to be electroplated
  • C25D5/38—Pretreatment of metallic surfaces to be electroplated of refractory metals or nickel
  • C25D5/40—Nickel; Chromium

Definitions

• 'rne present invention relates toa process for obtaining an adherent coating of electrode-
• posited material on.a chromium-containing alloy of iron and/or nickel and, more particularly, to
• a composite metal one layer of which is copper and another layer of which contains chromium or is constituted of a nickel-chromium-iron alloy.
• Considerable difficulty has heretofore been experienced in securing good adherence between the surface of a chromium-containing article, especially a nickel-chromium alloy of the stainless type and the surface of copper when the latter was formed by electrodeposition. Without satisfactory adherence between the foundation metal and the electrodeposited layer it is not possible to work or fabricate the product,
• certain processes attempted acid solution to an electroplating bath while still mium alloys from one tank to another in commercial practice rapidly enough to avoid danger of partial formation of a passive film on the article during the transfer period.
• a further object of the invention is the provision of a process for protecting a body made of chromium-containingalloy from which the passive film has been removed in a preparatory bath containing hydrochloric acid against reforming of such a film while the body is being transferred to a regular metal plating bath by forming on said body a protective metallic film while it is immersed in the preparatory bath.
• chromium alloy, stainless steel or the like which can be practiced on an industrial scale with conventional appliances and equipment and which is relatively cheap and permits wide commercial and industrial use.
• the article or body to be coated which is made of a chromium-containing alloy, is preferably freed from grease in the customary manner and then immersed in a bath containing hydrochloric acid to remove a passive film that forms on the surface of a chromium-containing alloy when it is exposed to air.
• a bath containing hydrochloric acid to remove a passive film that forms on the surface of a chromium-containing alloy when it is exposed to air.
• the article or body is not removed from the acid bath after the destruction of the passive film, but is coated, while still in the acid solution, with a layer, film or plate of a protective metal, such as nickel.
• I can accomplish the production of the formation of the nickel plate by adding an appropriate amount of nickel chloride to the solution containing hydrochloric acid and electrodepositing a film or plate of nickel upon the chromium-bearing surface of the article or body whil it is still immersed in the hydrochloric acid solution. Thereafter the article or body protected by a nickel plate or film can be safely removed from my special preparatory bath and transferred to the regular copper plating bath or the like without danger of the reforming or healing of the passive film.
• the coating metal such as copper, is then electrodeposited upon the article or body in the usual manner. It. has been found that the copper adheres tenaciously to the nickel-plated article or body and can be worked and fabricated without rupturing the bond between the layers.
• a body or article made of a nickel-chromiumiron alloy containing about 79% nickel, about 13% chromium, and about 7% iron was pumice scrubbed until there was no water break.
• the surface of the body or article may, of course, be degreased by any other suitable method,
• the nickel-chromium article or body was made anode for about 2 minutes at a current density of about amperes per square foot (2.2 amperes per square decimeter) using nickel electrodes as cathodes. While the article was maintained in the solution, the electric current was then re- I have found.
• anodically treated surface of the article for about 6 minutes at a current density of about 20 amperes per square foot (2.2 amperes per square decimeter).
• the composite body formed was characterized by such tenacious adherence of the copper layer to the foundation of the article that the bond was not broken when the,body was worked or fabricated including such working or fabricating operations as cold rolling or drawing. Satisfactory results were obtained by using a nickelchromium article having a thickness of about 0.03 of an inch (0.08 centimeter), a nickel protective film of about 0.00004 of an inch (0.0001 centimeter), and a copper layer of about 0.08 of an inch (0.2 centimeter).
• a process for producing copper plated chromium-containing bodies capable of withstanding accentuated cold rolling, drawing or working without separation of the copper plating therefrom which comprises degreasing a body containing about 79% nickel, about 7% iron and about 13% chromium, immersing said body in a preparatory solution containing about 240 grams per liter of nickel chloride and about 36 grams per liter of hydrochloric acid, making said body the anode of an electric circuit having nickel versed and nickel was electrodeposited on the 76 electrodes as cathodes, passing a current of about 20 amperes per square foot through said solution for about 2 minutes at a temperature of about 70 F., making said body the cathode and said nickel electrodes the anodes in said circuit, passing a current through said circuit at a current density of about 20 amperes per'square foot until a protective layer of nickel has been deposited on said body, only then removing said nickel plated body from said preparatory solution and transferring said nickel plated body to a copper
• a process for producing chromium-containing bodies having a thick plate of copper and capable of withstanding accentuated working including rolling and drawing without separation of the thick copper plating therefrom which comprises immersing a degreased body containing about 79% nickel, about 13% chromium and about 7% iron as an anode in an aqueous preparatory solution containing about 36 grams of hydrochloric acid per liter, passing a current of about 20 amperes per square foot for about 2 minutes through said preparatory solution to remove anodically a passive surface film from accuse said body and to provide said body with an active surface, making said body the cathode of an electric circuit having nickel anodes and having said aqueous preparatory solution as an elec-- passing an electric current at a current density ,of at least about 20 amperes per square foot through said solution containing nickel chloride until a thin protective layer of nickel having a thinness of about 0.0004 inch is electrodeposited on the active surface of said body, then transferring said nickel
• a process for producing chromium-containing bodies having a thick copper plating and capable of withstanding accentuated working including rolling and drawing without separation of the thick copper plating therefrom which comprises immersing a body made from an alloy containing chromium and at least one metal selected from the group consisting of nickel and iron in an aqueous preparatory solution con- 7 taining about 36 grams per liter of hydrochloric acid and nickel chloride, anodicaliy removing a passive surface film from the surface of said body by a current of about 20 amperes per square tectively plated chromium-containing body having a thin protective layer of said nickel. and thereafter transferring the protectively plated body to an aqueous acid copper plating bath and electrodepositing athicker layer of copper on said thin layer of nickel of said protectively plated body whereby a composite chromium-con.
• taining body having a thick plate of copper and capable of withstanding accentuated cold working without separation of the thick copper plating from the aforesaid body is produced.
• a process for'producing chromium containing bodies having a thick plate of copper and capable of withstanding accentuated working in- 7 eluding rolling. and drawing without separation of the thick copper plating from the base metal which comprises producing in an aqueous bath containing 36 grams of hydrochloric acid per liter an active surface on a degreased chromiumcontaining body by anodically treating at a current density of about 20 amperes per square foot for a period of time of at least 2 minutes in .said aqueous ba'th, adding about '240grams per liter of nickel chloride to said bath containing 36 grams of hydrochloric acid per liter, making said body having an active surface the cathode 0.00004 inch on said active surface. then transfoot for 2 minutes to leave an active surface.

Landscapes

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

Priority Applications (3)

Applications Claiming Priority (1)

Publications (1)

Family

ID=22648692

Family Applications (1)

Country Status (3)

Cited By (13)

Families Citing this family (4)

• 1937
  • 1937-12-01 US US177462A patent/US2285548A/en not_active Expired - Lifetime
• 1938
  • 1938-11-18 GB GB33617/38A patent/GB503008A/en not_active Expired
  • 1938-11-29 FR FR846768D patent/FR846768A/fr not_active Expired

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