ABSTRACT Several components in paint and plastic industry, like mixers, extrusion screws and dies, injection moulds, suffer heavily from abrasive wear. This wear is mainly induced by the presence of TiO 2 in the paint or in the plastic blend. Coating technology offers a solution to increase the wear resistance and consequently the lifetime of those components. The aim of this study is the evaluation of the micro-abrasive wear resistance of a range of commercially available hard and/or low friction coatings against rutile particles. Therefore, ball cratering tests EXPERIMENTAL SET-UP The tests were performed on a TE66 micro-scale abrasion tester manufactured by Plint. As abrasive suspensions, a typical rutile powder with small particle size (Ø 0.1-0.4 µm) and spherical grains in distilled water was used. Ball bearing steel was used as counterbody. The selected coatings ranged from hard ceramic coatings to softer low friction coatings. Four PVD coatings were used (TiN, CrN, TiCN and low temperature CrN), one CVD (TiN) and three PACVD (DLC and diamond-like nanocomposites Dylyn ® a-C:H/a-Si:O) TEST RESULTS AND EVALUATION The micro abrasion test resulted in a clear ranking of the selected coatings in function of the wear coefficient. In general, the hard ceramic coatings have the lowest wear coefficient. DLC and CrN performed very well. The softer coating types which are designed for reduction of the surface energy, such as NiP+PTFE, show an increase in wear of three orders of magnitude. However, there is no evidence for a close correlation between the wear rate and the coating hardness measured by depth sensing indentation. Only when the three very similar PACVD coatings are considered separately, the wear coefficient is significantly increasing with decreasing coating hardness. The results are obtained by using the extended Archard equation: with K c and K s are the wear coefficients of the coating and substrate respectively, V c and V s the measured wear volumes and SN the sliding distance multiplied by the applied load. Different ways of implementing equatio
