EFFECT OF BATH STABILIZERS ON ELECTROLESS NICKEL DEPOSITION ON FERROUS SUBSTRATES

A study has been made of electroless nickel (EN) deposition on ferrous substrates in the presence of four bath stabilizers-lead ion, iodate ion, mercaptobenzothiazole and maleic acid. Deposit morphology and spr eading of EN to carbon inclusions in carbon steel and gray cast iron w ere examined by SEM/EDS analysis. The porosity of EN coatings was meas ured as a function of bath stabilizer concentrations, It was found tha t the stabilizers retarded the rate of EN deposition on carbon inclusi ons and increased the porosity of EN coatings. Maleic acid decreased t he phosphorus content of EN coatings. Sulfur and lead codeposited in t he presence of mercaptobenzothiazole and lead ion, respectively. This paper summarizes the results of these investigations.