Tribological behavior of SAPS sprayed Al2O3-TiO2 and NiCr-Cr3C2 coatings under severe load conditions

Plasma sprayed Al2O3-TiO2 and NiCr-Cr3C2 coatings have been widely used in various components with severe wear conditions. In this study, the microstructure and friction-wear behavior of both coatings were comparatively studied in order to provide an insight into their tribological properties under heavy load. The results suggested that although both of the coatings showed almost the similar porosity and hardness, the wear rate of NiCr-Cr3C2 coating was only 44% as much as that of Al2O3-TiO2 due to a higher toughness. The delamination, grooves and pits were observed on the worn surface of Al2O3-TiO2 or NiCr-Cr3C2 coating. The wear behavior of both coatings was associated with abrasion, accompanied by a certain extent of delamination and adhesion. For Al2O3-TiO2 coating, the high hardness Al2O3 particles that deeply embedded in the surface of softer friction pair (Ni55) caused serious adhesive tearing and scratch under normal and radial stresses.