Mechanism of Chromium Electrodeposition as a Particular Case of Mechanism of Induced Codeposition of Metals

Abstract

The chromium reduction from standard worked-out chromium-plating electrolyte containing compounds of trivalent and hexavalent chromium and sulfuric acid is considered. It is shown that the reduction of Cr(III) ions with the formation of intermediate adsorbed Cr(II) species is the main electrochemical process. The intermediate species can be further electrochemically reduced to the metal or chemically interact with Cr(VI) species to form a cluster compound, which is stepwise reduced to the metal with a slow transfer of the first electron. Chromium reduction proceeds according to the mechanism of induced codeposition of metals proposed earlier.