Structural, mechanical and tribocorrosion performances of CrMoSiN coatings with various Mo contents in artificial seawater

CrMoSiN coatings containing various molybdenum (Mo) contents were prepared on Si wafers and titanium alloy substrates using unbalanced magnetron sputtering system via adjusting the Mo target current. The microstructures of CrMoSiN coatings were characterized by using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and transmission electron microscope (TEM), respectively. The mechanical properties of coatings were determined using scratch and nano-indentation tests, while the tribocorrosion behavior of coatings sliding against SiC balls in seawater was performed using a linear reciprocating motion of tribometer. The results showed that Cr(Mo)SiN coatings exhibited (2 0 0) preferred orientation. By adding the Mo element into CrSiN coating, an substitutional solid solution of (Cr, Mo)N was formed, and the columnar structure became significantly dense. Consequently, the coating surface changed from “fine-dome” like morphology to a relatively flat morphology with “groove-boundaries”. The hardness of CrMoSiN coatings accordingly increased to a maximum value of 35.5 GPa at the Mo content of 11.85 at.%. Due to the formation of MoO₃, the tribocorrosion performances of coatings were enhanced.