| 摘要 |
A plated aluminum product, and the method of making such product is disclosed for use in automotive bumpers. A plated outer decorative coating is used and is preferably constituted of chromium (0.000005-0.00005'' thick) on nickel (0.0003-0.003'' thick). An electroplated pretreatment system is employed between the outer decorative coating and aluminum alloy and consists essentially of at least a brass strike containing, for purposes of increased lateral corrosion resistance, an as-deposited copper content in the range of 60-75% by weight, and the aluminum substrate should preferably be restricted to a zinc content of 4.5-5.5%. The pretreatment system may be expanded to include a copper layer encased in two layers of brass, a first layer most adjacent the aluminum substrate containing said 60-75% copper and a second brass layer most adjacent the decorative coating containing 50-60% copper. The plating solution for carrying out the brass plating is constituted to provide enhanced covering and throwing power, and specifically may contain 3.6-9.6 oz./gal. sodium cyanide, the ratio of sodium cyanide to metal should be 0.12-1.6 times the metal, 2-5 oz./gal. sodium hydroxide, 4-12 oz./gal. sodium carbonate, and a total brass metal content of 3-6 oz./gal. divided to contain 68-85% copper and 15-32% zinc.
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