Electrodeposited Cr-Al₂O₃ composite coating for wear resistance

The co-deposition of Al₂O₃ particles with chromium is possible when a rare earth element is added into a conventional hexavalent chromium bath. The effect of various plating variables on the Al₂O₃ content of the coating was studied. When the coating contains about 0.7-1.0 wt.% of Al₂O₃, the hardness of the composite coating has the highest value of about 1300 Hv, and the wear resistance of this coating is increased by two to six times as compared with that of chromium coating. The cathode polarization curves show that the rare earth affects the electrode process of chromium deposition.