Dense VSiCN coatings deposited by filament-assisted reactive magnetron sputtering with varying amorphous phase precursor flow rates

Abstract

Phase-modulated VSiCN coatings were deposited with hot filament assistance by magnetron sputtering of a vanadium target in a gas mixture of argon, nitrogen, and hexamethyldisilazane (HMDS). HMDS flow conditions and total working pressure were varied to influence coating amorphous phase content (0 at.% ≤ Si ≤ 9 at.%). Scanning electron microscopy revealed that deposition with HMDS vapor disrupted columnar growth and increased coating growth rate by as much as 27% relative to a VN 0.8 reference. Coating surface morphologies were characterized by atomic force microscopy . A transition from a nodular appearance ( R q = 8.9 nm) for the VN 0.8 coating to a pitted appearance ( R q = 2.7 nm) for the coating containing 9 at.% Si was observed. X-ray diffraction analysis and transmission electron microscopy indicated that the VSiCN coatings contained a nanocrystalline B1-VC x N y phase and an amorphous phase, whose phase fraction increased with HMDS flow. The crystallographic out-of-plane preferred orientation of the VN 0.8 coating was (220) while all VSiCN coatings were (111) textured. Coating hardness and apparent elastic modulus were measured by nanoindentation . The VSiCN coating with 3 at.% Si exhibited the highest hardness of 31.4 GPa, which was 8.8 GPa greater than the VN 0.8 coating. Coating apparent elastic modulus decreased with increasing HMDS flow from 288 GPa to 188 GPa. All coatings exhibited excellent adhesion to stainless steel substrates as evaluated by the Rockwell indentation test . The disruption of columnar growth and incorporation of Si in VSiCN coatings is a possible method of improving the high temperature wear resistance of VN-based coatings. • Deposition of dense, non-columnar VSiCN coatings is demonstrated. • Hexamethyldisilazane (HMDS) vapor is used as an amorphous phase precursor. • Granular and pitted surface topographies are obtained with R q < 3 nm. • Coating preferred orientation is (220) for the VN 0.8 reference and (111) for VSiCN. • Hardness decreases from 31 GPa to 19 GPa with increasing amorphous phase content.