The effects of deposition parameters on the structure and properties of titanium-containing DLC films synthesized by cathodic arc plasma evaporation

Abstract

Titanium-containing diamond-like carbon films were deposited by mixing C+ and Ti+ plasma streams originating from cathodic arc plasma sources in argon (Ar). The deposition was processed at substrate bias voltages ranging from −50 to −300 V and a Ti target current ranging between 20 and 70 Amps. Film characteristics were investigated using Raman spectroscopy and high resolution X-ray photoelectron spectroscopy (HRXPS). The film microstructures were evaluated by using an atomic force microscope (AFM), a field emission scanning electron microscopy (FEGSEM), a glancing angle X-ray diffractometry (GAXRD) and a high-resolution transmission electron microscopy (HRTEM). Mechanical properties were investigated by using a nanoindentation tester, a ball on disc wear test and a scratch test. Raman spectra proved that the intensity of D and G bands decreased by increasing the bias voltage and Ti target currents. HRTEM results established that titanium-containing DLC films revealed a snake-skin like structure, consisting of nano scale TiC particles, comparable to GAXRD and HRXPS results. HRXPS analysis showed that the concentrations of titanium increased from 4.9 to 23.9 at.% and the C concentration proportionally decreased from 91.6 to 69.3 at.% as the Ti target current was gradually increased from 30 Amp to 70 Amp. Wear tests proved that the friction coefficient of titanium-containing DLC films were lower than that of DLC films. The scratch test also proved that the adhesive strength of Ti-DLC was significantly higher than that of conventional DLC.