TiC/a-C Nano-Composite Films Fabricated by Using Closed-Field Unbalanced Magnetron Sputtering for Biomedical Applications

Hydrogenated amorphous carbon films (a-C:H or DLC) exhibit high hardness, low friction coefficient, and high wear resistance. Variations in the tribological properties were studied for amorphous carbon films fabricated by using closed-field unbalanced magnetron sputtering with TiC thin films as an adhesive layer. The a-C, a-C:Ti, and TiC/a-C nano-composite films were prepared using closed-field unbalanced magnetron sputtering with graphite and titanium as targets. Various structures of Ti-doped a-C and TiC interlayers under the amorphous carbon (a-C) film were examined to improve the tribological properties, and characteristic changes in the nano-composite structure were observed. The structure of the nano-composite film showed improved tribological properties, including high hardness, low friction coefficient, low surface roughness, and good adhesion of the a-C thin films. With a Ti-doped a-C film in a laminated structure, the tribological properties were improved to a high hardness value of >28.5 GPa, a high elastic modulus of >250 GPa, and a smooth surface with a roughness of <0.1 nm.