Anodizing pretreatment for nickel plating
AssigneeKaiser Aluminum & Chemical Corporation
InventorHenry J. Wittrock
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Abstract
This invention relates to a process of pretreating an aluminum surface for subsequent nickel plating to provide improved adhesion and corrosion resistance. The pretreatment process comprises subjecting the aluminum surface to anodizing in a phosphoric acid electrolyte in such a manner so that the voltage is increased to operating levels within 30 seconds, preferably in less than 15 seconds.
Claims8
In the electrolytic plating of nickel onto an aluminum substrate having low levels of insoluble intermetallic particles wherein the aluminum substrate is first anodized in an acidic aqueous electrolyte containing only phosphoric acid as the acid species and then a layer of nickel is electrolytically plated onto the anodized substrate from an acidic aqueous solution containing at least one nickel compound, the improvement comprising controlling the anodizing procedure so that a predetermined voltage in the range between about 45 and 75 volts is reached within 30 seconds from the start of the anodizing procedure, causing a high initial current density not exceeding 120 amps/ft.sup.2 which decays to a level between 15 and 50 amps/ft.sup.2.
Dependencies are inferred from the claim text.