Improving high-temperature wear resistance of arc-evaporated AlCrN coatings by Mo alloying

AlCrN is an essential material system used as the protective coating for tools and components. In recent years, alloying strategy has attracted widespread attention to enhance the high-temperature properties of AlCrN coatings. Here, the mechanical and tribological properties of AlCrMoN hard coatings with various Mo contents were studied. For AlCrMoN coatings with Mo contents ranging from 0 to 10.4 at.%, the primary face-centered cubic structure with columnar grain morphology was obtained. AlCrMoN coatings showed an extremely low wear rate (on the order of 10−8 mm3/N·m) at room temperature. Whereas the addition of Mo did not reduce the friction coefficient as expected. Excellent wear resistance was achieved with the increase of Mo content at 600 °C, which connects to the modification of the tribolayer. The incorporation of molybdenum oxides increased the deformation ability of the tribolayer. Moreover, the enrichment of Mo at the interface was detected, forming a Mo–N–O interlayer. These two factors promoted the good adherence of the nanocrystalline tribolayer in the wear track and thus prevented further wear at 600 °C.