Electro-co-deposition of corrosion resistant nickel/zinc alloys onto steel substrates

Claim 1

An apparatus for the continuous plating of corrosion resistant coatings on iron or steel strip substrates which comprises, in combination, a plating line including a seriatim arrangement of cleansing and plating tanks, liquid segregation means between said tanks, and strip propulsion and advancing means; said plating tanks including a first nickel plating section fitted with nickel anodes and filled with a nickel ion-containing electrolyte and means for making said strip cathodic to deposit a substantially pure nickel priming layer on said strip, and a second alloy plating section fitted with zinc and nickel anodes and filled with an electrolyte maintained at a temperature range of 135° F. to 145° F., said electrolyte containing nickel and zinc ions, wherein the combined metal ion-content of nickel and zinc in the electrolyte is in the range of 10 to 25 oz/gal, the ratio of nickel to zinc in the electrolyte is in the range of 0.1 to 1 to 0.4 to 1 and the nickel ion content is in the range 1.4 to 3.5 oz/gal, said alloy plating section containing means for making said strip cathodic and providing a cathodic current density to said strip in the range of 15 to 120 amperes per square foot of strip; whereby the strip, after cleansing is advanced by said propulsion means to said first nickel plating section for the application of a nickel priming layer and then is advanced to said second section where said primed strip is then coated with a corrosion-resistant electrodeposited layer of a nickel/zinc alloy having a content of 10% to 14% nickel, the balance being zinc, wherein said first plating section and said second plating section are successive sections of a contiguous plating tank both sections of which are filled with the electrolyte of said second section, and wherein the current density in said first section is adjusted by said cathodic making means at less than about 10 amperes per square foot, then rising up to 15 to about 120 amperes per square foot for the subsequent alloy deposition.

Claim 2

An apparatus for the continuous plating of corrosion resistant coatings on iron or steel strip substrates which comprises, in combination, a plating line including a seriatim arrangement of cleansing and plating tanks, liquid segregation means between said tanks, and strip propulsion and advancing means; said plating tanks including a first nickel plating section fitted with nickel anodes and filled with a nickel ion-containing electrolyte and means for making said strip cathodic to deposit a substantially pure nickel priming layer on said strip, and a second alloy plating section fitted with zinc and nickel anodes and filled with an electrolyte maintained at a temperature range of 135° F. to 145° F., said electrolyte containing nickel and zinc ions, wherein the combined metal ion-content of nickel and zinc in the electrolyte is in the range of 10 to 25 oz/gal, the ratio of nickel to zinc in the electrolyte is in the range of 0.1 to 1 to 0.4 to 1 and the nickel ion content is in the range 1.4 to 3.5 oz/gal, said alloy plating section containing means for making said strip cathodic and providing a cathodic current density to said strip in the range of 15 to 120 amperes per square foot of strip; whereby the strip, after cleansing is advanced by said propulsion means to said first nickel plating section for the application of a nickel priming layer and then is advanced to said second section where said primed strip is then coated with a corrosion-resistant electrodeposited layer of a nickel/zinc alloy having a content of 10% to 14% nickel, the balance being zinc, wherein said first plating section and said second plating section are successive sections of a contiguous plating tank both sections of which are filled with the electrolyte of said second section, and wherein the current density in said first section is adjusted by said cathodic making means at less than about 10 amperes per square foot, then rising up to 15 to about 120 amperes per square foot for the subsequent alloy deposition.