抄録
It is significant to examine the properties of electrodeposited silver-copper alloys for electrical contacts. At first, plating conditions and bath compositions for electroplating of the alloys were studied. Since cyanide solutions were widely used for silver or copper plating, a cyanide bath was used in this study. Two kinds of anodes, consisting of copper and silver, were used. One was that, in which silver was connected with copper at the same electric potential (designated as “non-separated anode”) and the other was that, in which connected at different electric potentials (designated as “separated anode”).
The results obtained were as follows:
(1) Bath compositions agreed qualitatively with the calculated results from equilibrium dissociation constant.
(2) In the experiments of “separated anode”, each of silver and copper was dissolved, corresponding to anode current under optimum conditions, because each potential of silver and copper anodes could be controlled.
(3) Plating conditions and bath compositions for good finishing were investigated with “non-separated anode” as follows:
metallic silver 1.29g/l, metallic copper 47.7g/l, K2CO3 18.2g/l, free KCN 1.7g/l, pH=12.4, cathode current density 0.10-0.33A/dm2, cathode current efficiency 55-91%. Chemical compositions of deposited layers were in the range of 20-92% of Cu.
(4) The above investigations with “separated anode” were as follows:
metallic silver 0.15g/l, metallic copper 65.1g/l, K2CO3 18.1g/l, free KCN 1.9g/l, pH=12.3, anode current density of silver 0.01-0.20A/dm2 and that of copper 0.72-0.92A/dm2, cathode current efficiency 90-96%. Chemical compositions of deposited layers were in the range of 79-96% of Cu.
