Tribological and Mechanical Properties of Nanocrystalline TiN, TiAlN, and TiSiN PVD Coatings

TiN, TiAlN, and TiSiN coatings were deposited on the W6Mo5Cr4V2 steel substrate by hollow cathodicassisted multiarc ion plating technology. The tribological properties of these coatings are comparatively studied. The microstructure, element composition, nanomechanics, and wear properties of the substrate and coating surface of high-speed steel were evaluated by XRD, SEM, EDS, TEM, XPS, and nanoindentation tests. The results show that the mechanical properties of ternary coating TiAlN and TiSiN are improved compared with high-speed steel and binary TiN coatings, with TiAlN hardness and elastic modulus of 44.8 and 438.6 GPa and TiSiN hardness and elastic modulus of 34.8 and 333.2 GPa. The TiAlN coating has the strongest ability to resist plastic deformation due to solid solution strengthening. TiSiN can improve the plasticity and toughness of hard coatings after fine-grain strengthening. A strong positive correlation exists between the amount of sample wear and the H3⁄E∗2 value. The surface friction coefficients of TiN, TiAlN, and TiSiN were all small compared with high-speed steel, and the roughness at the wear tracks of high-speed steel increased while the roughness at the wear tracks of the coating samples decreased.