Abstract
There are several ways to characterize the wear resistance of coatings in the laboratory, almost all of them applying relatively low contact pressure, both punctually and over surface contact. Pin-on-disc, reciprocal sliding and micro-abrasion wear tests are quite common configurations for this purpose. Thus, a gap was identified in terms of characterization of hard PVD coatings subject to higher levels of contact pressure. This work aims to study and compare the wear behavior of two different coatings made by PVD, a B4C (Boron Carbide) monolayer, less used, and another following a multi-layer structure of CrN/CrCN/DLC, to identify the wear mechanisms involved in quite different coatings. Both coatings were initially characterized in terms of chemical composition, thickness, morphology, structure, hardness, and adhesion to the substrate, being subsequently tested in laboratory equipment for wear tests following the block-on-ring configuration and relatively high levels of contact pressure, with a view to study the failure mechanisms of the coatings and their wear rate. CrN/CrCN/DLC multilayered coatings presented a better overall wear behavior, whereas B4C coating showed a good wear behavior regarding the load and configuration used, but in line with the behavior already observed when other wear testing configurations had been used. Thus, under the conditions imposed, CrN/CrCN/DLC coatings is the best option when high contact pressure is applied to the coated surfaces.
TGO formation and oxygen diffusion in Al-rich gamma-TiAl PVD-coatings on TNM alloys
