Syntheses and mechanical properties of Ti-B-C coatings by a plasma-enhanced chemical vapor deposition

Ti-B-C coatings were synthesized on WC-Co and Si wafer substrates by PECVD technique using a gaseous mixture of TiCl4, BCl3, CH4, Ar, and H2. In this work, the boron content was varied in a wide range from TiC to TiB2, and microstructure and mechanical properties of synthesized Ti-B-C coatings were systematically investigated. From our instrumental analyses, the synthesized Ti-B-C coatings was concluded to be composites consisting of nanocrystallites TiC, quasi-amorphous TiB2, and amorphous carbon at low boron content, on the contrary, nanocrystallites TiB2, quasi-amorphous TiC, and amorphous carbon at relatively high boron content. The microhardness of the Ti-B-C coatings increased from ∼ 23 GPa of TiC to ∼ 38 GPa of Ti0.33B0.55C0.11 coatings with increasing the boron content. The Ti0.33B0.55C0.11 coatings showed lower average friction coefficient of 0.45, in addition, it showed relatively better wear behavior compared to other binary coatings of TiB2 and TiC.