Influence of crystallographic texture on friction in a-Al₂O₃/Ti(C,N) ceramic tool coatings

Abstract

This work explores the influence of the crystallographic texture on the resulting frictional response in two ceramic coatings systems containing top alpha-Al2O3 layer with no and fiber texture. The microstructure was analyzed by electron backscatter diffraction, the surface roughness was characterized by white light interferometry, and the micro hardness was measured by standard Vickers testing. The coefficient of friction (COF) was measured using ball-on-disk tribometry under linear reciprocating sliding motion. Our results verified a strong correlation between the crystallographic texture of the top alpha-Al2O3 layer and the resulting COF. This effect can be mainly attributed to the lowest critical shear stress within the basal dislocation slip {0001} < 11-20 >, which facilitates the generation of plastic deformation at the top surface layer. This work highlights the understanding of the complex correlations between microstructure and tribological performance of ceramic coatings.