Controlled nucleation and growth in chromium electroplating from molten LiCl-KCl

TLDR: In this article, the relationship between the electrochemical parameters and the resulting structures of chromium electrodeposits obtained by electrolysing chromous chloride (CrCl2) dissolved in the LiCl-KCl eutectic have been established.

Abstract: The relationships between the electrochemical parameters (which can be controlled) and the resulting structures of chromium electrodeposits obtained by electrolysing chromous chloride (CrCl2) dissolved in the LiCl-KCl eutectic have been established. The electrodeposition of chromium under ordinary potentiostatic conditions leads to pure chromium but this is not in a form to provide an adequate protective coating as it is difficult to avoid dendrite formation and low initial coverage together. These limitations can be overcome by the sequential use of a high overpotential pulse to initiate good coverage and continuing electrodeposition at low overpotential to minimize dendrite formation. The structures and morphologies of chromium electroplates were optimized. The good protective coatings that resulted were adherent, coherent and reasonably free of cracks and pores. The macro-and microthrowing powers of the bath were excellent and the high purity of the chromium electroplates led to low (130–280 HV) measured microhardness.