The Electrodeposition of Cobalt–Chromium Alloys from Sulfate–Oxalate Solutions

Abstract

The kinetics of separate and concurrent discharge of cobalt and chromium ions from sulfate–oxalate solutions is studied. Cobalt–chromium alloys with the cobalt content of 4 to 94% and carbon content of 1 to 4% are obtained. At a concurrent discharge of chromium and cobalt ions, the deposition potential of chromium is shifted by 150 to 200 mV in the positive direction. The shift depends on the current density and cannot be accounted for by the energy of mixing of the components. The alloying of chromium with cobalt decreases the overpotential of the hydrogen discharge. The codeposition with chromium did not decelerate the reduction of cobalt ions in contrast to the electrodeposition of nickel. The main reasons for the difference between the effect the alloying with chromium produces on the electrochemical reduction of nickel and cobalt, which are similar in their properties, are considered.