| 摘要 |
PURPOSE:To obtain uniform plating with high adhesive strength with a simple method by cathodically electrolyzing Al or an Al alloy in an aqueous chloride soln. and carrying out substituting plating. CONSTITUTION:This pretreatment is applicable to pure Al or an Al alloy, especially a slowly cooled industrial pure Al casting or high purity Al with >=99.99% purity. As an electrolytic soln. an aqueous soln. of sulfate or other salt besides NaCl or other chloride is used after adjusting to 3.5-11.5pH with acid or alkali. Current density adequate for the electrolysis is about 5-80A/dm<2>, and >= about 15sec is enough time to finish the electrolysis. By the electrolysis a fine rough surface is formed on the Al grain surface without excessively developing the grain boundaries, and by carrying out substituting plating by an ordinary method using Zn, Sn or an alloy thereof after the electrolysis, uniform plating with high adhesive strength is obtd. |
