Structure, Mechanical and Thermal Properties of TiSiWN Coatings

Abstract

Elemental alloying has been proven to be a valid approach for improving the performance of coatings and has attracted significant research attention. This study aims to explore the impact of W-addition on the structure, mechanical and thermal properties of arc evaporated TiSiN coatings. Ti0.88Si0.12N coating presents a single-phase structure of fcc-(Ti, Si)N, while Ti0.88Si0.08W0.04N and Ti0.84Si0.09W0.07N coatings show a fcc-(Ti, Si, W)N and bcc-W dual-phase structure. As the W content increases, the surface quality of our coatings is obviously improved on account of the pronounced reduction in growth defects, including macroparticles and holes. Introduction of W slightly increases the hardness from 40.0 ± 0.5 GPa for Ti0.88Si0.12N to 41.6 ± 1.1 GPa for Ti0.88Si0.08W0.04N and 42.0 ± 1.0 GPa for Ti0.84Si0.09W0.07N. All our coatings possess a high thermal stability with their hardness values remaining above 38 GPa even after annealing at 1100 °C. Meanwhile, as a result of the suppressed anatase to rutile TiO2 transformation, alloying with W ameliorates the oxidation resistance of TiSiN coatings. After 750 °C oxidation for 10 h, the W-containing coatings only reveal oxide layers of ~301.5 (Ti0.88Si0.08W0.04N) and 279.2 nm (Ti0.84Si0.09W0.07N), whereas Ti0.88Si0.12N coating has already been entirely oxidized.