The Additions of V and Cu on the Microstructure and Mechanical Properties of Mo-N Coatings

Due to the excellent lubricity of V2O5 and soft metals, V and Cu have been added to Mo-N based coatings to further improve the tribological properties. In this study, the Mo-V-Cu-N coatings were deposited by high power impulse magnetron sputtering (HIPIMS). The effects of V and Cu on the microstructure and mechanical properties of Mo-N coatings were investigated. With increasing V/Cu content ratio, the deposition rate decreased from 15.4 to 6.5 nm/min, and the microstructure transformed from a featureless structure into a dense columnar structure. At low Cu contents, less than 6.5 at.%, the Mo-V-Cu-N coatings exhibited a single solid solution phase of c-Mo2(V)N. When the Cu content reached 29.7 at.%, the Mo45V1Cu30N24 coating showed the lowest surface roughness of 2.0 nm, and the coating changed into a double-phase of c-Mo2(V)N and c-Cu. The adhesion strength gradually increased from 32.2 to 87.8 N with an increasing V/Cu content ratio. Due to the microstructure densification, a maximum hardness of 27.3 GPa was achieved for the Mo46V15Cu1N38 coating, which was accompanied by a high compressive residual stress.