A series of researches was carried out to study the effect of addition agents, agitation of plating solution, supply of periodically interchanged current sources of d. c. and a. c. and the using of the soluble or insoluble anode on the properties of the thick deposits of tungsten-cobalt electroplating.
The result is as follows:
(1) The violent agitation of plating solution by air bubble was most effective to make the grain size small even if the thickness of the deposit was over 50 microns, while it caused the slight decrease of tungsten content of the deposit. The addition of gelatine or dextrine to the plating bath as well as the supply of interchanged current sources of d. c. and a. c. also contributed to produce fairly fine deposits, but the effect was not so remarkable as that by agitation of solution.
(2) Long period electrodeposition by using the insoluble anode as Pt brought about considerable changes in the tungsten content, crystal structure, microscopic structure of the deposit and current efficiency. In contrast to this, the using of Co anode was favorable to keep the state of deposition more stable.
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