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.