MICROSTRUCTURAL CHARACTERIZATION AND WEAR BEHAVIOR OF WC-CoCr COATING ON AZ91 MAGNESIUM ALLOY

This paper includes the microstructural and wear characterization of WC-10Co4Cr coating on AZ91 magnesium alloy. Using the scanning electron microscopy and X-ray diffraction analysis it was determined that the microstructure was formed by WC particles, CoCr matrix, present Co3W3C mixed carbide, W2C, and free carbon. The presence of W2C and free carbon indicates the partial decarburization during the spraying process. The microhardness of HVOF-sprayed coating was 1480 +/- 80 HV 0.05, which is approximately 20x higher when compared to AZ91 alloy. The friction coefficient values with the subsequent weight loss of the coating and magnesium substrate were determined. It has been proven that HVOF-sprayed WC-CoCr coating can protect the magnesium substrate from the wear.