Abstract
The properties and mechanism of peeling on nickel electroforming were investigated changing the activation treatment, the surface roughness of substrate and varying the treatment conditions (concentration, time, and temperature) of potassium dichromate solution. The results obtained are : the peeling force increases with an increse of the arithmetrical mean roughness (Ra) when the activation treatment is carried out. That is, the peeling force is proportional to Ra. Activating the surface of the substrate with an acid such as sulfuric acid reduces the peeling force below about one-half. The content (at%) of chromium in the film increases with an increse of the concentration of potassium dichromate and the treatment time. The peeling forces decrease with an increse of the content of chromium and the treatment time. On the other hand, the treatment temperature does not affect the thickness and the content of chromium in chromate film. On the basis of the results, it may be concluded that the important parameters affecting the peeling properties are as follows : firstly the roughness of surface, secondly the activation, and thirdly the conditions of chromate treatment. From measuring the thickness and content of chromate film on a substrate by AES analysis, it was found that the peeling occurs in the layer of chromate film.
