The influence of Mo target current on the microstructure, mechanical and tribological properties of CrMoSiCN coatings in artificial seawater

CrMoSiCN coatings were successfully deposited on Si wafers and titanium alloy substrates using unbalance magnetron sputtering system, and the Mo content in coatings was controlled by adjusting the Mo target current. The topography and microstructures of CrMoSiCN coatings were observed and detected using scanning electron microscope (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. The mechanical properties of coatings were characterized using scratch and nano-indentation tests, while the tribological behavior of coatings sliding against Al₂O₃ balls in seawater was performed using ball-on-disk wear tests. The results showed that (Cr, Mo)N substitutional solid solution was formed in the CrMoSiCN coatings, and more of the Mo₂N phase appeared as the Mo target current increased. The maximum values of hardness and elastic modulus were 24.8 GPa and 321.7 GPa when the Mo target current was 2 A (10.1 at.% Mo content). The friction coefficient of CrMoSiCN/Al₂O₃ tribopairs decreased with an increase in the Mo target current. The minimum mean-steady friction coefficient was 0.37 at the Mo target current of 3 A (16.3 at.% Mo content), while the minimum specific wear rate of coatings was 1.5 × 10⁻⁶ mm³/Nm at the Mo target current of 0.5 A.