Enhancement of tribological properties of DLC by incorporation of amorphous titanium using magnetron sputtering process

Titanium-diamond-like carbon (Ti-DLC) composite coatings were deposited on 304 SUS substrates by periodic sputtering of Ti in between DLC deposition with different Ti target powers using a magnetron sputtering system. Microstructure as well as the mechanical and tribological properties of the Ti-DLC composite coatings were highly dependent on the Ti target power which was varied from 75 to 150 W. Transmission electron microscopy (TEM) confirmed that the Ti atoms in DLC coatings were in an amorphous state which was beneficial for deterring crack nucleation within the coating. Furthermore, premature delamination of a pure DLC coating with a thickness of similar to 330nm could be prevented by inclusion of Ti in DLC. All the Ti-DLC composite coatings were capable of drastically enhancing the friction and wear properties of bare 304 SUS. The coating deposited with a target power of 85 W showed the highest wear resistance with a wear rate of similar to 3.13 x 10(-11) mm(3)/N mm, which was extremely low for a dry sliding condition. This outcome was attributed to ultra-fine distribution of amorphous Ti in DLC which led to low internal stress and high I-D/I-G ratio of the coating.