Abstract
The plating condition of W-Co alloys in citrate solution and the corrosion resistance of its alloys in acid solution were investigated.
The result was as follows:
1. Optimum composition of bath was Na2WO4⋅2H2O 60gl/, CoSO4⋅7H2O 20g/l, and sodium citrate 60g/l, from which the bright deposits containing about 50% tungsten were obtained at pH 8.0, current density 5A/dm2, and temperature 70°C.
2. Alloy deposits and their tungsten contents were mainly affected by concentration of cobalt in the bath, but the effect of concentration of tungsten or sodium citrate was not so remarkable. When the plating was continued more than one hour, the deposits became grayish, and then occurred peeling.
3. The corrosion resistance of W-Co alloy deposits was found to be fairly good in HCl and HNO3 solutions, like that of W-Fe alloy deposits. W-Ni alloy deposits, however, were inferior to bath W-Co and W-Fe alloy deposits.
