| 摘要 |
The invention provides a pretreatment process for electroplating aluminum parts or strip, in which the zincating solution is modified to improve the adhesion of the subsequent electroplate to the substrate. The aluminum part or strip, such as an aluminum coin blank or strip for coin blanks, is pretreated with an improved zincate solution which provides hydroxide ions in an amount in the range of 75-175 gpl, zinc ions in an amount in the range of 15-40 gpl, nickel ions in an amount in the range of 2-10 gpl and copper ions in an amount in the range of 1.5-5 gpl. The pretreatment process preferably includes a copper strike applied from a copper cyanide strike bath at a pH in the range of 8.5-11.0, using a current density in the range of 0.1-10 A/dm2. The pretreatment and electroplating steps arc preferably conducted by barrel plating, in accordance with another aspect of the invention. The invention also provides electroplated aluminum parts or strip, such as electroplated coin blanks, including a substrate formed from aluminum or an aluminum alloy and having multiple surfaces, a layer of zincate on at least one of the surfaces of the substrate and preferably completely encasing the substrate, a strike layer of a strike metal covering the layer of zincate, and one or more electroplated layers of one or more metals covering the strike layer, said one or more electroplated layers adhering to the substrate to withstand a deformation process without delamination from the substrate. |
