Comparative tribological study of air plasma sprayed WC-12%Co coating versus conventional hard chromium electrodeposit

In this work, the properties of air plasma sprayed WC-12%Co coating before and after heat treatment were compared with the properties of the hard chromium electrodeposit. WC-12%Co coatings were heat treated at 650, 900 and 1150 degrees C for 1 h in an argon atmosphere. XRD patterns confirmed the formation of an amorphous phase in the as-sprayed coating. This amorphous phase gradually transformed to eta-carbides in the course of heat treatment of the coating. This transformation was confirmed by the XRD analysis of the coatings heat treated above 900 degrees C. Pin-on-disc wear test results showed that WC-12%Co coatings had a significantly better tribological performance as compared with that of the hard chromium electrodeposits. The results also indicated that heat treatment of the WC-12%Co coatings at 900 degrees C gave the highest wear resistance among the coatings, which was due to the formation of hard eta-carbides at this temperature. (C) 2009 Elsevier Ltd. All rights reserved.