Characterization and properties of quaternary Mo–Si–C–N coatings synthesized by magnetron sputtering technique

In this paper the direct current unbalanced reactive magnetron sputtering and composite target techniques were exploited to deposit quaternary Mo–Si–C–N coatings on Si wafer and stainless steel (1Cr18Ni9) in an Ar/N2 gaseous mixture. The chemical composition, microstructure, morphology, hardness, and friction coefficient of these films were characterized by means of X-ray diffraction, XPS, field emission scanning electron microscopy, TEM and nanoindentation. With the increase of C content in the range of C/(C + Mo + Si + N) = 0–12 at.%, the crystallite size decreases from 32 nm to 5 nm and the average friction coefficient of Mo–Si–C–N coatings decreases from 0.24 to 0.17, while the hardness increases at first and then decreases after passing a maximum value of about 27 GPa at 9 at.% C. It was suggested that in the Mo–Si–C–N coatings C atoms substitute for the N atoms in the nano-sized crystalline Mo2N to form Mo2N(C) solid solution phase and the microstructure of the Mo–Si–C–N coatings may be nano-sized crystalline Mo2N(C) embedded in the amorphous SiNx and CNx phases.

Research Highlights
► The friction coefficient of Mo–Si–C–N coatings reached 0.17.
► The hardness reached a maximum value of about 27 GPa at 7 at% C.
► The coatings consist of nano-crystallites Mo2N(C) embedded in SiNx and CNx phases.