Tribological behavior and wear mechanism of nanomultilayer AlCrN/AlTiSiN coatings at elevated temperatures

Wear resistance is a critical property of tool coatings for high-speed machining, which depends on mechanical properties and oxidation resistance of the coatings. Many works have demonstrated that AlTiSiN coating has good mechanical properties. Additionally, AlCrN coating exhibits excellent oxidation resistance. The multilayered structure has proved to improve comprehensive properties of the coatings. Therefore, AlCrN/AlTiSiN multilayer coating has a high potential to be used in machining applications. This paper focuses on the high-temperature tribological behavior of AlCrN/AlTiSiN multilayer coating. The results show that AlCrN/AlTiSiN coating exhibits good to acceptable wear resistance up to 800 °C. Meanwhile, AlCrN/AlTiSiN coating also displays the lowest friction coefficient of ∼0.5 and a wear rate of 1.8 × 10−6 mm3/N m at 800 °C, which is about 58.13% and 64.0% lower than that of AlCrN and AlTiSiN coatings, respectively. The imaging and composition analysis of the high-temperature wear tracks allowed for explaining the differences in wear mechanisms. At 800 °C, a dense thin tribofilm is formed on the surface of AlCrN/AlTiSiN coating, which acts as a glaze layer to impede wear. It provides a strategy for enhancing the wear resistance of monolayer coating in high temperatures, which combines the advantages of both high oxidation resistance of one layer and high hardness of the other layer.