Investigation of the properties of Cr coatings deposited in an improved Cr(III) electrolyte

Abstract

In this study, mechanical and tribological properties of Cr coatings obtained from a Cr(III) sulfate bath with addition of the heterocyclic compound (HCC) prepared on mild steel have been investigated. The chromium plating electrolyte containing the HCC additive enables us to deposit the Cr coatings at low (20°C) temperature and low current densities. Small amounts (from 20 to 60 mgl^–1) of HCC were added to the Cr(III) sulfate bath in order to study the effects of HCC on coating formation. At an optimal concentration of 40 mgl^–1, the HCC additive to the solution ensures a high surface microhardness of the Cr deposits obtained (HV_0.05 = 1036 kg mm^–2) without a subsequent heat treatment. The dry sliding wear tests have shown that the Cr coatings have both a low friction coefficient and a low wear rate. The Cr(III) bath with the HCC additive is more eco-friendly and requires less energy compared with a conventional Cr(III) process.