Wear behavior of microwave-annealed and cryogenically treated thermal spray coatings: A comparative evaluation

Abstract

In this current study, two post-processing techniques, i.e. microwave annealing and cryogenic treatment were employed on WC-10Co-4C detonation gun (D-gun) coating to improve the tribological properties. The effect of both the post-treatment on the microstructure and mechanical properties was studied using optical micrograph (OM), scanning electron microscopy (SEM), X-ray diffractometry (XRD) and energy-dispersive X-ray spectroscopy (EDS). Microwave annealing, resulted in a significant change in the size and morphology of WC particles. However, cryogenic processing showed minimal variation with slight decrease in the WC particle size. Phase changes were observed after both the post-treatment techniques. The cryogenically treated sample showed considerable improvement in the hardness while there was a slight reduction in the hardness after microwave processing. Among all the coatings, the microwave processed sample had the highest fracture toughness. The improvement in hardness after the cryogenic process was attributed to the formation of η phase and the presence of nano precipitates in the coating matrix. Cryogenically treated coating showed significant improvement in the wear resistance of the WC D-gun coating due to the improvement in the microhardness in the coating.