Effect of carbon content on the microstructure and properties of W–Si–C–N coatings fabricated by magnetron sputtering

A series of W–Si–C (4–5 at.%)–N nanocomposite coatings with different C contents have been deposited on Si wafer substrates by reactive magnetron sputtering of W–Si–C composite target in Ar + N2 mixed atmosphere. Microstructure characteristics and mechanical properties of W–Si–C–N coatings were investigated in this paper. Results exhibited that W–Si–C–N coatings possess nanocomposite microstructure where nano-crystallites W2(C, N) embedded in amorphous matrix of Si3N4/CNx/C. As the C content increased, the hardness and Youngs’ modulus of the W–Si–C–N coatings first increased and then decreased, reaching the maximum value of approximate 36 GPa and 382 GPa, respectively, for coatings containing 11.1 at.% C. All the coatings are in compressive stress state, ranging from 0.8 to 2.0 GPa. In addition, friction coefficient of the W–Si–C–N coatings considerably decreased with the increase of C content.

► W–Si–C–N hard coatings were sputter deposited on silicon substrate using direct current magnetron sputtering technique.
► W–Si–C–N coatings were composed of nc-W2(C, N) and a-Si3N4/CNx/C.
► Hardness and Youngs’ modulus of W–Si–C–N coatings reached maximum value of 36 and 382 GPa, respectively.
► Residual stress built in coatings are in compressive state, ranging from 1.8 to 2.0 GPa.
► The lowest friction coefficient of W–Si–C–N coatings is 0.26.