Effect of high energy shot peening on the wear resistance of TiN films on a TA2 surface

Abstract

TiN films were deposited by pulsed magnetron sputtering on the surface of pure titanium TA2 treated or not treated with high-energy shot peening (HESP). The morphology and crystal structure of the TiN thin films were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The film-substrate adhesion, hardness and modulus of elasticity of the TiN films were measured by a scratch tester and a nanoindentation tester. The wear resistance of the TiN films was measured by a microtribotester. The results showed that, compared with the original pure titanium, the TA2 surface treated by HESP exhibited a large number of defects and a high chemical activity, which enabled the surface to quickly capture and fix Ti and N plasma during the sputtering process and induced heterogeneous nucleation, thus leading to the refinement of the grain size of the TiN film and a thicker and denser film. With prolongation of the HESP time, film-substrate adhesion increased from 20.1 N for the original TA2 to 39.2 N for the 30-min HESP-treated TA2, and the nanohardness of the TiN films increased from 14.0 GPa for the original TA2 to 29.7 GPa for the 30-min HESP-treated TA2. HESP treatment could stabilize the friction coefficient and improve the wear resistance of TiN thin films. The specific wear rate of TiN films decreased from 0.061 mm3/N·m for the original TA2 to 0.029 mm3/N·m for the 30-min HESP-treated TA2.