Improving the wear and corrosion resistance of Ti–6Al–4V alloy by deposition of TiSiN nanocomposite coating with pulsed-DC PACVD

In this work, titanium silicon nitride (TiSiN) hard ceramic coatings were deposited on Ti-6Al-4V bio-alloy to improve its wear and corrosion resistance via pulsed-DC plasma-assisted chemical vapor deposition (PACVD) method. The results showed that TiSiN coatings are composed of TiN nano-crystallites embedded in the amorphous SiNx matrix. Increasing the Si content of coating from 0 to 25.1wt%, leads to a significant reduction of its thickness from 4 to 0.5µm due to the occurrence of the controlled surface reaction phenomena. Using SiCl4 as the Si precursor for the TiSiN coatings results in increasing the surface roughness from 20.8nm of the TiN coating up to 31.4nm for the TiSiN coating with 25.1wt% Si due to the strong etching effect of SiCl4. Si addition up to 17.2wt%, reduces the TiN grains size which considerably raises the hardness (about 1000HV0.01) and also wear resistance of TiSiN coating due to the formation of the SiNx amorphous matrix and its grain growth-prohibiting effect. The electrochemical tests in simulated body fluid (SBF) represented the higher corrosion resistance of TiSiN coatings in comparison with Ti-6Al-4V alloy. The higher corrosion resistance of TiSiN coating is related to its nano-composite structure and also the formation of silicon dioxide passive layer beside the titanium dioxide layer on the surface of this coating. The highest wear resistance and corrosion protective efficiency of 77% was achieved for the TiSiN coatings with 17.2wt% and 11.3wt% of Si, respectively. [Display omitted] •The TiSiN coatings with different Si contents were deposited on Ti6Al4V by PACVD.•The microstructural, tribological and corrosion tests were performed on coatings.•The best wear resistance was obtained for the coating with 17.2wt% of Si.