クエン酸浴によるニッケル-タングステン合金メッキの浴組成と表面状態について

抄録

The compositions of citric acid-ammonia baths for Ni-W alloy plating were studied for practical purposes as well as conditions of electrolysis, amount and component ratio of the alloy deposited.
The results obtained were as follows:
(1) The composition and amount of the alloy deposited were kept constant in a relatively wide range of variation in composition of the baths containing nickel sulfate, sodium tungstate, and citric acid, and a deposit of good quality, containing 35-40% of W, was obtained.
(2) A deposit of good quality was also obtained by the addition of ammonium citrate as a complexing agent. However, pH of the bath had to be adjusted to about 9.0 with sodium hydroxide.
(3) The addition of a small amount of hydrazine sulfate as a reducing agent was effective in the improvement of deposition efficiency.
(4) The hardness of Ni-W alloy deposit as plated was 500-600Hv. It was elevated to 900-1000Hv by the heat treatment at 500-600°C in a vacuum furnace.
(5) Ni-W alloy plating was converted into Ni-W solid solution when it was heat- treated at 500-600°C.