Residual stress in Ni–W electrodeposits

In the present work, the residual stress in Ni–W layers electrodeposited from electrolytes based on NiSO4 and Na2WO4, is investigated. Citrate, glycine and triethanolamine were used as complexing agents, enabling complex formation between the nickel ion and tungstate. The results show that the type of complexing agent and the current efficiency have an influence on the residual stress. In all cases, an increase in tensile stress in the deposit with time after deposition was observed. Pulse plating could improve the stress level for the electrolyte containing equal amounts of citrate, glycine and triethanolamine (TEA) as complexing agent. An additive as 1,3,6 naphthalene trisulphonic acid which has a grain refining effect, and chloride, which enables dissolution of metal during the anodic cycle, reduced crack occurrence in the electrodeposits.