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

Quaternary Ti–B–C–N films were synthesized on AISI 304 and Si wafer by a PECVD technique using a gaseous mixture of TiCl4, BCl3, CH4, Ar, N2, and H2. The microstructure of Ti–B–C–N films was characterized by instrumental analyses of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron microscopy (HRTEM) in this work. Our Ti–B(9 at.%)–C–N coatings had a fine composite microstructure consisting of nano-sized Ti(C,N) crystallites surrounded by amorphous BN phase. The micro-hardness of Ti–B–C–N coatings steeply increased from ∼ 21 GPa of Ti–C–N up to ∼ 42 GPa of Ti–B(9 at.%)–C–N films. In addition, Ti–B–C–N coatings showed the lowest average friction coefficient compared with other coatings of TiN, TiC, and Ti–C–N coatings prepared under the same PECVD condition. A systematic investigation of the microstructure and mechanical properties of Ti–B–C–N coatings with various boron contents is reported in this paper.