Influence of trimethylsilane flow on the microstructure, mechanical and tribological properties of CrSiCN coatings in water lubrication

•CrSiCN coatings with different Si and C contents were deposited.•CrSiCN coatings consisted of Cr(C,N) nanocrystallites and amorphous phases such as a-Si3N4(SiC, SiCN) and a-C(a-CNx).•CrSiCN coatings exhibited the highest hardness of 21.3GPa at the TMS flow of 10sccm.•CrSiCN coatings deposited at the TMS flow of 10sccm possessed the excellent tribological properties in water.•The wear mechanism changed from tribochemical wear to mechanical wear when the TMS flow increased. CrSiCN coatings with different silicon and carbon contents were deposited on silicon wafers and 316L stainless steels using unbalanced magnetron sputtering via adjusting trimethylsilane (TMS) flow, and their microstructure and mechanical properties were characterized by X-ray diffraction (XRD), scanning electron microscopy(SEM), X-ray photoelectrons spectroscopy(XPS) and nano-indenter, respectively. The tribological properties of CrSiCN coatings sliding against SiC balls in water were investigated using ball-on-disk tribometer. The results showed that the CrSiCN coatings had fine composite microstructure consisting of nanocrystallites of Cr(C, N) crystal and amorphous phases such as a-Si3N4 and a-C(a-CNx). The typical columnar structures changed from fine cluster to coarse ones when the Si content was beyond 3.4at.%. With an increase in the TMS flow, the hardness and Young's modulus of Corsican coatings all first increased, and then rapidly decreased, but the compressive stress in the coatings varied in the range of 2.8–4.8GPa. When the TMS flow was 10sccm, the CrSiCN coatings exhibited the highest hardness of 21.3GPa and the lowest friction coefficient (0.11) and wear rate (8.4×10−8mm3/Nm). But when the TMS flow was beyond 15sccm, the tribological properties of CrSiCN coatings in water became poor.