Influences of bias voltage on mechanical and tribological properties of Ti-Al-C films synthesized by magnetron sputtering

Ti-Al-C films were deposited on silicon (100) substrates using magnetron sputtering TiAl target and graphite target in argon atmosphere at various substrate negative bias voltages. The composition, surface morphology, hardness and friction coefficient of the resulting films were characterized using x-ray photoelectron spectroscope, energy dispersive spectrometry, atomic force microscopy, nanoindentation and tribological tester. Results show that the structure and properties of the deposited films strongly depend on the applied substrate negative bias voltage. The Ti-Al-C films deposited at high substrate negative bias voltage show high surface roughness, low hardness and short wear life. In contrast, the Ti-Al-C films deposited without negative bias voltage exhibit uniform and smooth surface, a high hardness of approximately 37 GPa and low friction coefficient and long wear life. Excellent friction and wear behaviors of the Ti-Al-C films deposited without negative bias may be attributed to the dense structure and high hardness.