Elevated temperatures erosion wear behavior of HVOF sprayed WC-Co-Cr/Mo coatings on Ti6Al4V substrate

Abstract

The present research aims to investigate the effect of different impact angles and temperatures on volumetric erosion loss of WC-Co-Cr coating containing 10 wt% Mo. The composite coating was developed using High-Velocity Oxy Fuel (HVOF) process on a titanium substrate (Ti-31). A solid particle erosion behavior of the coatings is carried out at different impact angles (30°, 60°, and 90°) and temperatures (200 °C, 400 °C,600 °C, and 800 °C). The volumetric erosion loss of the coated samples was measured using an air jet erosion tester at high temperatures using Al2O3 as an erodent. The XRD, SEM/EDS, porosity, density, microhardness, bond strength, and scratch tests characterized the as-sprayed coatings. The 3D optical profilometer was employed to evaluate the volumetric erosion loss and the mode of erosion. The scratch resistance of WC-Co-Cr coating is better than WC-Co-Cr/Mo coating. The WC-Co-Cr coating shows a brittle mode of erosion up to 600 °C and a ductile mode of erosion at 800 °C. In contrast, the WC-Co-Cr/Mo coating shows a brittle mode of erosion at 200 °C and a mixed mode of erosion at 400 °C to 800 °C. The volumetric erosion loss of WC-Co-Cr is less than WC-Co-Cr/Mo for all temperatures and impact angles. The formation of oxide phases on the coating surfaces demonstrates erosion resistance at high temperatures. The results of volumetric erosion loss measured by the weight loss method correlate well with a non-contact type 3D optical profilometer.