| 摘要 |
1288026 Copper immersion coating R KALLENBACH 11 Sept 1970 [17 Sept 1969] 43657/70 Heading C7F Al or Al alloy is coated with Cu by electrochemical displacement in the absence of externally applied current by immersion in an acid bath containing divalent Cu, at least part of which is present as a cupric-oxalic complex. There is claimed a bath for the above process, consisting of an acidic aqueous solution of a Cu salt, a source of oxalate ions in sufficient quantity for formation of the complex, and alkali metal or ammonium ions. Preferred amounts of ingredients are Cu; 1-8g/l; K or NH 4 , 4-16g/l; chloride (e.g. from CuCl 2 ) 1-10g/l; and oxalic acid, 10-80g/l; the bath preferably has pH 2-6 and is used at 20-90‹ C. The Cu in the bath is preferably maintained near saturation concentration, e.g. by maintaining solid salt in the bath, and the bath is replenished with CuCO 3 and/or Cu oxalate. In an example, Al-Si alloy is coated using the above method, electro-plated with Ni, mechanically polished and chrome-plated. Other post-treatments disclosed are electrolytic thickening of the Cu or treatment with chromate or dichromate solution. |
