Abstract
In order to solve the faults of electrodeposited cobalt described in the previous papers, the authors studied a new type of bath containing cobalt sulfate and sodium citrate.
The following conclusions were reached.
1) Components and conditions suitable for plating were as follows:
(a) Concentration of cobalt sulfate was above 0.5mol/l.
(b) Ratio of concentration in mol between cobalt sulfate and sodium citrate was 1:0.5-1:1.3.
(c) The value of pH was 4-7, and preferably 5-6 in practice.
(d) Ammonium sulfamate and 2. butyne-1.4 diol were possible to be used as additive agents.
2) The plating baths mentioned above contained complex ions and excess of cations.
3) These baths were suitable for being used for insoluble anode, because they had a wide range of controlling conditions as mentioned above.
