Evaluation of High Temperature Dry Sliding Wear Behaviour of Thermal Sprayed and Microwave Fused WC12Co and CeO2 Modified WC12Co Composite Coatings

Abstract

Thermal spray methods are used to increase the wear resistance of working surfaces. Microwave post-treatment is the advanced approach for enhancing the properties of thermal spray coatings. The current investigation focuses on the wear behavior of HVOF-sprayed and microwave-treated coatings. The WC12Co and CeO2 modified WC12Co composite coatings were successfully deposited on AISI4140 steel using the HVOF thermal spray technique. The coatings were tested in both as-sprayed and microwave post-treatment conditions. The dry sliding wear tests were carried out at temperatures of RT, 200, 400, and 600 ℃ with various loads. Vickers hardness tester, Scanning Electron Microscopy (SEM), and X-ray diffraction (XRD) equipments were used to investigate the microhardness, microstructure, and phases of coatings, respectively. In both compositions, the microwave-fused coating had a fine homogeneous structure and higher hardness than the as-sprayed depositions. For typical loads of 20 N and 40 N for both compositions, the friction coefficient decreased with increasing temperature in the as-sprayed and fused coatings. At all conditions, the microwave fused coating outperforms the as-sprayed coating in terms of wear resistance. During sliding action, the fused coatings exhibit tribo-oxide layers, which provide the best wear resistance of the microwave fused composite coatings. The wear resistance of the WC12Co coatings is improved as compared to CeO2 modified WC12Co coatings.