| 摘要 |
In some cases, it is necessary to coat aluminum with nickel, and the most difficult operating conditions are probably met here in the case of aluminum pistons in internal combustion engines. With known processes, adhesion problems occur in the further coating with other metals. Without intermediate activation, satisfactory solutions are not obtained. However, the problem is solved by high proportions of nickel sulfate, small proportions of an acid which stabilizes the pH values, and very small proportions of a fluoride which loosens the oxide layer appearing in the licer bath, of a chloride which promotes the dissolution of the nickel anodes and of a phosphite which improves the adhesive strength of the nickel layer. The solids are kept in suspension in the bath by vigorous circulation, for example by means of air. The particle size should preferably be 3 micrometers.
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