Abstract:Ternary Ti-B-N coatings were synthesized on AISI 304 and Si wafer by plasma-enhanced chemical vapor deposition (PECVD) technique using a gaseous mixture of TiCl₄, BCl₃, H₂, N₂, and Ar. By virtue of X-ray diffraction analysis, X-ray photoelectron spectroscopy, scanning electron microscope, and high-resolution transmission electron microscope, the influences of B content on the microstructure and properties of Ti-B-N coatings were investigated systematically. The results indicated that the microstructure and mechanical properties of Ti-B-N coatings largely depend on the transformation from FCC-TiN phase to HCP-TiB₂ phase. With increasing B content and decreasing N content in the coatings, the coating microstructure evolves gradually from FCC-TiN/a-BN to HCP-TiB₂/a-BN via FCC-TiN+HCP-TiB₂/a-BN. The highest microhardness of about 34 GPa is achieved, which corresponds to the nanocomposite Ti-63%B-N (mole fraction) coating consisting of the HCP-TiB₂ nano-crystallites and amorphous BN phase. The lowest friction-coefficient was observed for the nanocomposite Ti-41%B-N (mole fraction) coating consisting of the FCC-TiN nanocrystallites and amorphous BN phase.

Key words: Ti?B?N coating; plasma-enhanced chemical vapor deposition (PECVD); nanocomposite coating; hardness; friction coefficient