No.8（2005）5.Corrosion resistance of bright deposits in nickel citrate electroplating

Tadashi DOI, Keiko YOSHIMOTO, Satomi UEHARA, Yoshio YAMAMOTO, Nobuo TAKAHASHI

For coping with the strict regulations on the drainage of boron established for environmental protection in Japan, the authors have developed a new nickel electroplating bath (a citrate bath) using citric acid instead of boric acid in a Watts bath. The citrate bath is a simple plating bath prepared by merely substituting boric acid in the Watts bath with citric acid and plating comparable with that of the Watts bath can be attained by using an existent facilities and under the same operation conditions. In order to clarify the corrosion resistance of bright deposits obtained from the citrate bath, a neutral salt spray test, a ferroxyl test, CASS test and measurements of electric potential of deposits were performed, and compared with those of the Watts bath. The difference between the both baths was observed in the corrosion resistance test, as a result of different mechanisms of electrodepostion and the different effects of brighteners in both baths. However, it was found that the corrosion resistance of the bright deposits obtained from the citrate bath was almost equivalent to that of the Watts bath. We concluded that the citrate bath offers an excellent, practical, and more environmentally friendly alternative to the use of boric acid in the Watts bath for bright nickel decorative and protective plating.

Keywords

Nickel citrate electroplating, Bright deposits, Corrosion resistance, Watts bath

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