抄録
It has been well known that the corrosion resistance of electroless nickel plating film by acid plating solution is superior to that of electroplated nickel film by Watt's bath. Effects of pH of plating solution, sort of nickel salt used, and kind of acid for dipping solution on the corrosion resistance of electroless nickel plating film were studied; in which the last effects were investigated by electrolytic polarization method, Ferroxyl tests, salt spray test, and outdoor exposure test. The following results were obtained.
1) The results of nickel sulfate were better than those of nickel chloride for the constituent of electroless nickel plating solution.
2) The decreasing order of corrosion resistance of plating film with plating solution was as follows; acid>ammoniacal>alkaline. However, the order with outdoor exposure tests was not the same as above.
3) When plating film was relatively thin, hydrochloric acid was not suitable for the pretreatment of steel substrate: while, when it was thick, there were almost no effects of the acid on its corrosion resistance.
