Investigating the Abrasive Wear Resistance of Thermal-Sprayed WC-Based Coatings

Abstract

The purpose of this research was to investigate the abrasive wear behavior of WC–NiMoCrFeCo (WC-N) and WC–FeCrAl (WC-F) coatings deposited by high-velocity oxygen fuel (HVOF) spraying. The abrasive wear resistance was evaluated by a dry sand rubber wheel (DSRW) test rig using abrasives silica 70 and alumina 60, and the values were then compared to those of conventional WC-Co (WC-C) coatings. The abrasive wear with silica 70 indicated the “soft abrasion” regime, while alumina 60 abrasive caused a “hard abrasion” for all coatings. Moreover, the wear rate of the coatings abraded by alumina 60 was around 1.2-7.8 times greater than that of silica 70. WC-F exhibited the greatest wear resistance compared to other coatings tested by silica 70 due to its lower mean free path and higher hardness compared to other coatings. WC-C coating revealed the cobalt matrix removal followed by WC fracture and pullout using abrasive silica 70, while WC-F and WC-N coatings represented a combination of subsurface cracking, WC pullout, and fracture. Abraded by alumina 60, WC-C, WC-F, and WC-N coatings showed the evidence of grooving, pitting, and cutting. Moreover, WC-C coating had the highest wear resistance due to its high fracture toughness and low porosity, protecting WC-C coating against severe cracking and grooving, respectively. Cross-sectional images of the wear scars revealed a significant sub-surface cracking for WC-F and WC-N coatings while no significant cracking could be detected for WC-C coating.