Preparation and characterization of multilayered titanium/titanium-diamond-like carbon films

The titanium/titanium diamond-like carbon (Ti/Ti-DLC) multi-layered films are deposited by combined electron cyclotron resonance microwave plasma enhanced chemical vapor deposition method and mid-frequency magnetron sputtering method using acetylene as the reactive gas and Ti target with a purity of 99.99%. The structures, compositions and surface morphologies of the samples are characterized by X-ray diffraction, scanning electron microscope, and X-ray photoelectron spectrometer. The mechanical properties of Ti/Ti-DLC multilayer films are investigated by microhardness tester, friction wear test instrument and surface roughmeter. The results show that TiC phase appears in multilayered film. The main growth mode of the film is island mode and there exists columnar crystal structure neither in Ti layer nor Ti-DLC layer. The properties of the multi-layered film, including composite hardness, friction coefficient, surface morphology and surface roughness are affected by the modulation period Lambda. It is shown that nano-hardening effect takes place when Lambda is small while large particles appear on the surface of the film, leading to a large surface roughness and friction coefficient. The layered structure of the film is not clear when Lambda <= 50 nm.