Microstructure and Tribological Performance of Electrodeposited Cr Coating with Trivalent–Chromium Electrolyte

Abstract

A chromium (Cr) coating was fabricated on 45 steel by electrodeposition with a trivalent–chromium (Cr3+) electrolyte. The morphologies and element distributions of the obtained coating were analyzed using a scanning electronic microscope, energy dispersive spectrometer, atomic force microscope, x-ray diffraction, and x-ray photoelectron spectroscopy. The effects of normal load and sliding speed on the tribological performance of the Cr coating were analyzed using a friction tester. The results show that the Cr coating with the roughness of 85.5 nm is composed of the Cr phase. The average coefficients of friction (COFs) of the Cr coating under the normal loads of 1 N, 3 N, and 5 N are decreased from 1.08 to 0.69, exhibiting excellent friction reduction; while its wear rates increase with the increase of the normal load, and the wear resistance becomes poor. Moreover, the average COFs of Cr coating at the sliding speeds of 600 times/min, 700 times/min, and 800 times/min are in the range of 0.71–0.76, and the wear rate is the lowest at the sliding speed of 700 times/min, showing that the friction reduction under the normal load of 3 N and wear resistance at the sliding speed of 700 times/min are the best.