Effect of CrMoN addition on the thermal stability and cyclic impact resistance of TiVN coatings

By adding V atoms to TiN, the tribological and mechanical properties of TiVN coatings are improved. Multilayered coatings, rather than monolayered ones, may further enhance the mechanical properties and thermal stabilities of TiVN. Therefore, an approach was employed in this study to synthesize gradient-and-multilayered CrMoN/TiVN coatings through vacuum arc ion plating. During the impact fatigue test that utilized a cyclic loading device, the correlation between cyclic impact resistance and coating structures of the deposited coatings were evaluated. Vacuum annealing and high temperature oxidation at temperatures exceeding 600 °C were used to assess the thermal stability of the coatings. Although the as-deposited TiVN coating achieved the highest hardness of 30.2 ± 2.5 GPa, the CrMoN/TiVN multilayer coating only experienced a slight decrease to 29.1 ± 2.2 GPa, which exceeded the solid solution quaternary CrMoTiVN mixture rule prediction. When compared to the high-hardness monolayered TiVN and the low-hardness CrMoN, the CrMoN/TiVN multilayer coatings demonstrated the best resistance to cyclic impact. The TiVN coating displayed the worst oxidation resistance, as shown by the emergence of elongated vanadium-rich Ti-V oxide slats on the surface after oxidation. The CrMoN coating exhibited higher oxidation resistance than TiVN, and small granular chromium oxides formed on the surface beyond 700 °C. The addition of CrMoN to TiVN to form CrMoN/TiVN resulted in improved oxidation resistance by inhibiting the oxidation of TiVN. A different oxidation behavior was found for the CrMoN/TiVN coatings. The design of gradient-and-multilayered CrMoN/TiVN coatings is proven to be advantageous for applications that aim to enhance the thermal stability and cyclic impact resistance of mechanical tools.