Influence of material properties on the wear of composite coatings

Aluminium matrix composite (AlMC) materials are finding more and more applications in machine construction. The addition of reinforcing materials to the matrix significantly improves the composite wear resistance. However, the presence of particles of a very hard, ceramic phase (Al2O3 and SiC) increases the wear of the sliding counterpart operating against the composite. Therefore, there exists a need to find methods of protecting the counterpart from the excessive wear. Cr+Al2O3 coating on cast iron piston rings running against the AlMC composite cylinders and anodic hard coating+metal (AHC+metal) type composite layer on engine cylinders elaborated at the Department of Material Science of the University of Silesia in Katowice are examples of such methods. In this paper, the mechanism of wear of the cast iron paired with AHC+Ni composite surface layer is presented. It is shown that wear depends on local material properties and stereological characteristics of the surface layer. The finite element method was used to determine the local stresses and strains.