Effect of S on Passivation of Ni Plating

Nickel plating containing intentionally introduced S was produced to obtain Ni film that is resistant to passivation, and the oxidative dissolution of the film was investigated. Dull Watt's and bright Watt's baths were used as base baths. In order to prepare the plating baths for the production of S-containing Ni films, colloidal S formed by decomposition of Na 2 S 2 O 3 was dispersed into the base baths. The colloidal S dispersion allowed Ni films with high S contents to be obtained from these baths, with a maximum S content of 3.8 atom % achieved. The Ni films produced using the plating baths containing dispersed colloidal S inhibited the passivation of the Ni films, with this suppression increasing with increasing S content. The Ni film obtained from the bright Watt's bath had higher concentration of S relative to the Ni film obtained from the dull Watt's bath and inhibited the passivation more strongly.