Mechanical properties of carbon-doped TIN films by ion beam irradiation in ethylene gas atmosphere

Carbon-doped TiN films were prepared on a AISI 304 stainless steel substrate by dynamic ion mixing technique and He+ ion irradiation in an ethylene gas atmosphere. The composition and structure of the films were analyzed by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) measurement. In addition, the Knoop hardness and coefficient of friction of the films were measured, and the influence of an ethylene gas pressure on the mechanical properties was investigated. he XPS measurement, the doped carbon resulted in Gaussian-like carbon depth profiles with a maximum concentration of 40 at.%, and in the formation of titanium carbide and graphite in the surface of TiN film. Carbon-doped TiN films exhibit higher hardness value of 2300–2550 kgf/mm2 and a low friction coefficient of 0.15 in comparison with TiN film. From these measurements of XPS, XRD and mechanical properties, it was clear that mechanical properties for carbon-doped TiN were affected by concentration and chemical state of carbon in the surface layer of TiN.