Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D3/00—Electroplating: Baths therefor
  • C25D3/02—Electroplating: Baths therefor from solutions
  • C25D3/56—Electroplating: Baths therefor from solutions of alloys
  • C25D3/565—Electroplating: Baths therefor from solutions of alloys containing more than 50% by weight of zinc

Definitions

• a method of electroplating a nickel-zinc alloy on a steel strip is described, in which the plating bath is maintained within a selected pH range, through use of a preselected ratio of nickel to zinc in the bath, and a preselected plating current density, whereby an electroplated coating is formed having a nickel content of from 9.5 to 12.5%, which coating has a low internal stress, and increased resistance to corrosion.
• the corrosion resistance or salt spray life, in hours, of the flat coating is increased from 122 hours to 160 hours and 156 hours respectively
• the salt spray life of the bent edge of the coating is increased from 133 hours to 156 hours and 172 hours respectively
• the salt spray life of the bent edge of the coating is increased from 98 hours to 133 hours and 145 hours respectively.
• Ni-Zn metal ratio 0. 63 0. 60 0. 56 0. 59 0. 58
• plating bath having a pH of from 2.5 to 3.5, in which nickel chloride and zinc chloride have been dissolved in sufficient amounts for each gallon of the bath to have a zinc content of from 8 to 10 ounces and a nickel content of from 4 to 5 ounces, and in which the strip is made a cathode as it passes through the bath, and an electroplating current density of 50 to 100 amperes per square foot of cathode surface of the strip is maintained, whereby a zinc-nickel alloy coating is electrodeposited on the steel strip, the alloy consisting of from 6.5 to 9.5% nickel with the remainder zinc.
• the bath is maintained at a temperature of from to F.
• the aforesaid coating is characterized by the fact that it has an expansive internal stress of about 500 to 1400 p.s.i., and has substantially greater corrosion resistance than zinc.
• the zinc in the bath is provided in the form of zinc chloride (ZnCl and the nickel in the form of nickel chloride (NiCl 6H O)
• the wetting agent is used to lower the surface tension of the bath to eliminate pitting, if encountered, and to improve the uniformity of deposit appearance.
• the identity of the wetting agents chosen is not important, although they must, of course, be compatible with the bath and cause no deleterious effects.
• Some of the wetting agents used in commercial nickel plating have been found to be satisfactory, as, for example, sulfated or sulfonated lauryl alcohol, one of the commonest so used. Others which produce less foam may be preferred, but the selection of such Wetting agents most suitable for specific conditions is well within the knowledge of those skilled in the art of electroplating, there being a wide variety available from purveyors of materials for nickel plating processes.
• the pH value of the bath should be maintained between 4.0 and 4.5, the bath temperature at 125-135 F., the current density at 40-100 a.s.f., and the percentage of nickel in the deposit within the range of 9.5 to 12.5%, with 11% as the optimum. Chanpes in the nickel content of the deposit, within this range are efiected primarily by changing the nickel-zinc metal ratio in the bath. An increase in the pH value of the bath beyond 4.5 is undesirable, due to the fact that this results in an increase in the expansive stress produced in the deposit.
• the method of plating steel strip with a zinc-nickel alloy which comprises: causing the strip to traverse an aqueous plating bath having a pH of from 4.0 to 4.5, in which nickel chloride and zinc chloride have been dissolved in sufficient amounts for each gallon of the bath to have a zinc content of from 7 to 9 ounces and a nickel content of from 4 to ounces; making said strip a cathode as it passes through said bath and maintaining an electroplating current density of from 40 to 100 amperes per square foot of cathode surface of the strip, whereby a zinc-nickel alloy coating is electrodeposited on the steel strip, said zinc-nickel alloy consisting of from 9.5 to
• a method of plating a metallic article with a zincnickel alloy which comprises: coating the article in an aqueous plating bath having a pH of from 4.0 to 4.5, in which nickel chloride and zinc chloride have been dissolved in sufiicient amounts for each gallon of the bath to have a zinc content of from 7 to 9 ounces and a nickel content of from 4 to 5 ounces; making the article a cathode in the bath and maintaining an electroplating current density of from to amperes per square foot of cathode surface of the article, whereby a zinc-nickel alloy coating is electrodeposited on the article, said zincnickel alloy consisting of from 9.5 to 12.5% nickel with the remainder zinc, and which coating has substantially greater corrosion resistance than a coating produced under like condition, but having a pH value of the bath of less' than 4.

Landscapes

• 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)

Applications Claiming Priority (1)

Publications (1)

Family

ID=25166262

Family Applications (1)

Country Status (8)

Cited By (12)

• 1969
  • 1969-01-31 US US795713*A patent/US3558442A/en not_active Expired - Lifetime
  • 1969-07-07 JP JP44054056A patent/JPS4932172B1/ja active Pending
  • 1969-07-23 GB GB37151/69A patent/GB1224680A/en not_active Expired
  • 1969-07-29 FR FR6925904A patent/FR2029731A1/fr active Pending
  • 1969-07-30 LU LU59192D patent/LU59192A1/xx unknown
  • 1969-07-30 BE BE736791D patent/BE736791A/xx not_active IP Right Cessation
  • 1969-08-21 NL NL696912739A patent/NL140293B/xx not_active IP Right Cessation
• 1971
  • 1971-09-01 ES ES371102A patent/ES371102A1/es not_active Expired

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