Wear resistance and wear mechanisms of WC-12%Co thermal sprayed coatings in three-body abrasion

In this study, the three-body abrasion resistance of AISI 1020 annealed steel samples coated with WC-12%Co coatings produced by the Jet Kote(R) thermal spray process was evaluated. The tests were performed using SiO2, Al2O3 and SiC as abrasives and five levels of stress ranging from 0.10 to 0.60 MPa. By measuring the weight loss, the wear rate was evaluated after reaching the steady state of wear. Characterisation of the abrasives was performed using an image analyser and scanning electron microscopy. The microstructure and wear mechanisms of the coatings were characterised by scanning electron microscopy. The relationship between stress and wear rate was found to be dependant on abrasive type; this is due to different degrees of fragmentation of the abrasive. The effect of stress on the wear rate depended on the nature of the abrasive due to the fragmentation process of the abrasives. The results indicated that abrasion resistance and predominant wear mechanisms were strongly dependent on abrasive hardness. In tests using SiO2 abrasive a combination of micropolishing associated with gradual degradation of the lamellae was the predominant wear mechanism. Plastic deformation by microploughing and microcutting were the predominant wear mechanism in tests with Al2O3 abrasive. In tests with SiC abrasive, interlamellar brittle fracture was the predominant mechanism. (C) 1999 Elsevier Science S.A. All rights reserved.