Dry sliding wear behavior of PVD TiN, Ti55Al45N, and Ti35Al65N coatings at temperatures up to 600 °C

Three PVD nitride coatings (TiN, Ti55Al45N, and Ti35Al65N) with different Al content were deposited on the cemented carbides by cathode arc-evaporation technique. Microstructural and fundamental properties of these nitride coatings were examined. The friction and wear behavior of these coatings were evaluated at temperatures up to 600 °C. The wear surface features of the test samples were examined by scanning electron microscopy. Results showed that the friction coefficient of these nitride coatings is different depending on the temperature. The friction coefficient of TiN coating increased with the increase of test temperature; while the friction coefficient of Ti55Al45N and Ti35Al65N coatings with the addition of Al decreased with the increase of test temperature. The Ti55Al45N and Ti35Al65N coatings exhibited higher wear resistance over the one without Al (TiN coating). The wear resistance of these nitride coatings at high temperature wear tests is significantly dependent on their tribological oxidation behavior. The Ti55Al45N and Ti35Al65N coatings with the addition of Al exhibited improved wear resistance as compared to the TiN coating, which was attributed to that their tribo-chemically formed Al2O3 exhibited better tribological properties than the TiO2 of the latter.