MICRO-ABRASION WEAR TESTING OF MULTILAYER NANOCOMPOSITE TiAlSiN/TiSiN/TiAlN HARD COATINGS DEPOSITED ON THE AISI H11 STEEL

Abstract

Nanostructured hard coatings are widely used to improve the wear resistance of tool steels in tribological applications. These coatings generally work under abrasive conditions and, therefore, a determination of their abrasive wear resistance has great importance. In this study, the free-ball micro-scale abrasion test, based on the ball-crater technique, has been used to evaluate the wear resistance of a multilayer nanocomposite nc-TiAlSiN/TiSiN/TiAlN hard coating. The coating was deposited on the AISI H11 cold-work tool steel using the industrial magnetron sputtering system. The microhardness and adhesion of the coating to the substrate were measured with the nanoindentation and scratch tests, respectively. The war tests have been performed using SiC abrasive slurry on ball-cratering equipment. The crater-wear volumes have been evaluated using an optical microscope (OM). An analysis of the worn craters was conducted with a scanning electron microscope (SEM). It was found that the nc-TiAlSiN/TiSiN/TiAlN hard coating has a better adhesion to the AISI H11 steel substrate and a higher abrasive wear resistance than a conventional TiN coating. A two-fold increase in the sliding speed resulted in an approximately two-fold increase in the removed-wear volume. Three different wear mechanisms, i.e., micro-scratch, lateral fracture and plastic deformation, took place on the craters formed on the nc-TiAlSiN/TiSiN/TiAlN coated steel.