CrAlN coatings are widely used for surface protection because of their excellent properties. Alloying with additional elements has been shown to effectively modify mechanical and tribological behavior of these coatings. In this study, CrAlMoxN coatings (x = 0–18.83 at%) were prepared by an arc ion plating technology, corresponding to CrAlN and Mo-doped variants CrAlMoN-1, CrAlMoN-2 and CrAlMoN-3, respectively). The effects of Mo incorporation on the microstructure, mechanical properties, and friction-wear performance at both room and high temperature were systematically investigated. Results indicate that Mo dissolves into the CrAlN lattice to form a solid-solution structure, which induces lattice expansion as confirmed by the shift of XRD peaks toward lower angles. Furthermore, a moderate addition of Mo substantially improves the hardness, toughness, and crack propagation resistance of the coatings. All four coatings exhibit friction coefficients of approximately 0.5 at room temperature. However, at 600 °C, the CrAlMoN-2 coating demonstrates a much more stable friction coefficient curve and achieves the lowest average friction coefficient of 0.75, together with a wear rate of 3.94 × 10−6 mm3/N·m, indicating greatly improved high-temperature tribological performance.
Yang et al. (Tue,) studied this question.