Abstract
Effects of organic and metallic impurities in bright nickel plating bath on the corrosion resistance and surface appearance of nickel-chromium plating were examined.
Organic compounds were the substances supposed to be produced by oxidation or reduction of 2-butyne-1·4 diol. Metallic impurities included Cu (II), Zn (II), and Mn (II).
CASS and SO2 tests were conducted on the corrosion resistance for organic impurities, but CASS test only for metallic impurities.
The follwing conclusions were drawn from the results of experiments.
The accumulated oxidized impurities, in particular, acetylene-dicarboxylic acid, tartaric acid, an glycolic acid had worse effects on the properties of nickel-chromium plating than reduced impurities. The following results were obtained.
1) Decrease in corrosion resistance of ncikel-chromium platings.
2) Decrease in leveling power of nickel deposits.
3) Formation of milky semi-bright deposits.
It was suggested the allowable limits of the contents of metallic impurities with respect to corrosion resistance and appearance were as follows:
Zn (II) up to 0.05g/l Cu (II) up to 0.02g/l and Mn (II) up to 5g/l
