Structure and wear characteristics of TiCN nanocomposite coatings fabricated by reactive plasma spraying

In this present work, titanium carbonitride (TiCN) coatings were successfully fabricated by reactive plasma spraying from agglomerated Ti-graphite feedstock under reactive nitrogen atmosphere. The microstructure and morphology were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution TEM. The mechanical and tribological performances were measured using a nanoindentation tester, tensile tester and block-on-ring tribometer. Results show that typical equiaxed grains with size about 40-90 nm is obtained. The as-sprayed coating consists of nano scaled TiC0.7N0.3, TiC0.3N0.7 and Ti2O crystalline phases with some amorphous phases (graphite and CNx), which would influence the mechanical and tribological properties of coating directly. When compared with TiN coating, TiCN coating exhibits a higher hardness and higher H/E and H3/E2 ratios with values of 27.1 GP, 0.1 and 0.3 GPa, respectively. This could benefit TiCN coating possessing high deformation resistance and large elastic recoverability to reduce the damage by impact and wear. Furthermore, the main wear mechanism of TiCN coating is tribo-oxidation wear and abrasive wear.