Electroplating of wear-resistant nanocrystalline coatings from a bath containing basic chromium(III) sulfate (chrome tanning agent)

Abstract

Regularities of the electroplating of chromium-carbon alloy coatings from a bath containing basic chromium(III) sulfate, carbamide, formic acid, sodium sulfate, aluminum sulfate, orthoboric acid, and sodium dodecyl sulfate are studied. Replacement of chromium sulfate as a source of trivalent chromium ions in the solution with basic chromium sulfate (chrome tanning agent) results in a decrease in the current density when metal deposition begins. As a result, the covering power of the bath increases. The effects discovered are determined by changes in the composition of the discharged chromium complexes. A certain excess of OH− groups in the inner sphere of electroactive chromium complexes results in acceleration of electroplating. The studied electrolyte based on chrome tanning agent enables one to produce thick high-quality nanocrystalline Cr-C alloy coatings with improved tribological characteristics.