An Approach on Evaluation Technique of Tribological Properties of PVD

Abstract

In this paper, we propose slurry jet, a new type of solid particle impact test, in order to quickly evaluate wear properties of physical vapor deposited (PVD) coating drills in commercial use. By slurry jet 1μm alumina particles were impacted at high velocity perpendicular to thin PVD coatings of TiN, TiN/CrN, TiN/TiAlN deposited on a high speed steel (HSS) substrate material. The geometry of the worn surfaces was measured with a stylus profilometer at each test interval. The distance between the original and worn surface at the deepest position was measured and designated as the wear depth. Linear wear was obtained for both coating and substrate material, and the penetration through the coating into the substrate was signified by a sharp increase in slope of the wear versus time curve. In addition our tests were found to be highly reproducible for coating drills. The TiN coating drills proved to have much higher wear resistance than the substrate material. The PVD coatings deposited on the drills showed the same wear rates as those on the plate specimens as reference samples. We conclude that our proposed evaluation technique for coating drills is considerably useful as screening test when evaluating coating tools. For the coatings included in this study, the TiN/TiAlN proved to have the highest wear resistance, whereas the TiN/CrN was the worst.