Optimization of PVD parameters for the deposition of ultrahard Ti-Si-B-N coatings

Multicomponent Ti-Si-B-N coatings were deposited on high-speed steel (HSS) substrates by reactive magnetron sputtering using a SHS TiB + 20 wt% Si target. The influences of the substrate temperature, bias voltage, and nitrogen partial pressure on the structure and the elemental compositions of the films were studied. The films were characterized by high-resolution transmission electron microscopy (HRTEM), Auger spectroscopy (AES), and X-ray diffraction (XRD). The results of HRTEM analysis indicated the formation of an ordered-disordered structure with fine crystalline grains of hexagonal Ti(B,N)(x) phase and amorphous integrain layers, The stoichiometry of the Ti(B,N)(x) phase was strongly affected by PVD process parameters. The films were characterized in terms of their microhardness and wear resistance. The reasons for the high value of microhardness appear to be the result of stoichiometric phase composition, compressive residual stress, and dense and fine microstructure of the Ti-Si-B-N coatings. The tribological wear test results indicated the superior wear-resistant properties of Ti-Si-B-N coatings compared to TiN and Ti(C,N) coatings.