Abstract
Tungsten-iron alloys were deposited from ammoniacal alkaline tartrate electrolytes in a wide range of metal composition. The iduced codposition was studied by steady-state and galvanostatic pulsed d.c. electrolysis, X-ray diffraction of electrodeposits, and direct chemical analysis of the metal composition of the solution sorbed on the electrode surface. Comparison of alloy composition was made between the alloy obtained by steady-state d.c. electrolysis and the alloys obtained by interrupted galvanostatic pulsed d.c. electrolysis. The result showed that, in the steady state of electrolysis, the tungsten percentage of the metal contained in the solution adjacent to the cathode surface was extremely higher than that in the bulk of the electrolytes having different metal compositions. The result of direct chemical analysis of the solution near the cathode surface showed that the preferential deposition of tungsten was not an anomalous phenomenon. It was found that the preferential deposition of tungsten occurred by the following interaction between electrolytes and cathode materials. (a) There was a preferential adsorption of tungsten in some ionic state, and (b) The tungsten percentage of the metal contained in the adsorbed layer, covering both of non-polarized and polarized electrodes, was higher than that in the electrodeposits.
