Proceedings of the Korean Institute of Surface Engineering Conference (한국표면공학회:학술대회논문집)

The Korean Institute of Surface Engineering (한국표면공학회)
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Influence of some additives on the process of Ni-W alloy electroplating

  • Wu, Yi-Yong (School of Materials Science and Engineering, Harbin Institute of Technology) ;
  • Kim, Dong-Soo (Surface Engineering Department, Korea Institute of Machinery and Materials) ;
  • Chang, Do-Yon (Surface Engineering Department, Korea Institute of Machinery and Materials) ;
  • Kwon, Sik-Chol (Surface Engineering Department, Korea Institute of Machinery and Materials)
  • Published : 2001.11.01
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Abstract

Ni-W alloy deposit is one of the best alternatives to hard chromium plating because of its good mechanical properties (high hardness, high strength, and good wear resistance). Ni-W alloy is deposited from weakly acidic or alkaline electrolytic bath with nickel sulfate, sodium tungstate or APT, and some kinds of organic hydroxy-acid complex and ammonia salts. W content of the deposit can be changed from 0 to 5Owt% and the coating with high W content is more attracted. But, meanwhile, the deposited layers are always found high internal stress, which cause them to become brittle and to bond insufficiently with the substrate. On the second hand, as the W content is incresed, the current efficiency reduced, which results in large quantities of hydrogen evolution and then produces bubbles on surface and pitting appearance In this paper, the influence of some additives on Ni-W alloy electroplating was investigated by means of compositional analysis and SEM. The initial results showed that 2-butyne-1,4-diol was the best brightener for Ni-W plating process. It could brighten and level deposit, but decreased the cathodic current efficiency. Its optimum concentration range is from O.lgjL to 0.5gjL. Besides, three kinds of additives including 2-butyne-1,4-diol were examined with Dagguchi method.

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