Effects of constituent layers and interfaces on the mechanical and tribological properties of metal (Cr, Zr)/ceramic (CrN, ZrN) multilayer systems

The influences of constituent layers and interfaces on the mechanical and tribological behaviors of metal (Cr, Zr)/ceramic (CrN, ZrN) multilayer coatings were systematically investigated in the present study. Four sets of multilayer coatings (Cr/CrN, Cr/ZrN, Zr/CrN and Zr/ZrN) with the same number of interfaces were synthesized by multi-arc ion plating technique. The crystalline structures of the multilayer coatings were determined by Xray diffraction and morphologies were observed by scanning electron microscope and transmission electron microscope. Furthermore, the nanoindenter, Vicker indenter, scratch tester and ball-on-disk tribometer were employed to evaluate the hardness, indentation toughness, adhesion strength and tribological properties of as-prepared coatings, respectively. Results revealed that the multilayer coatings with different constitute layers and interfaces presented different microstructures and properties. Based on the analysis of the cross-sectional indentation topographies, Zr interlayers exhibited higher crack resistances compared to Cr interlayers. Zr/CrN multilayer coating showed the highest hardness of 28 GPa, the strongest strength adhesion (> 100 N) and the lowest wear rate. The excellent tribological performance of Zr/CrN multilayer coating was mainly ascribed to the high crack resistance of Zr layer, high wear-resistant layer of CrN as well as the local coherent interface between Zr and CrN sublayers.