Improved tribological, electrochemical and biocompatibility properties of Ti6Al4V alloy by gas-nitriding and Ti-C:H coating

Ti-C:H coatings are deposited on untreated Ti6Al4V alloy samples and high-temperature gas-nitrided Ti6Al4V alloy samples by means of CFUBMS. Therefore, four types of specimen, i.e., Ti6Al4V, nitrided Ti6Al4V (N-Ti6Al4V), T-C:H-coated Ti6Al4V (Ti-C:H/Ti6Al4V) and T-C:H-coated nitrided Ti6Al4V (Ti-C:H/N-Ti6Al4V) are considered. The microstructure, adhesion and hardness of the Ti-C:H coatings are examined using a Raman spectrometer, scratch tester and nanoindenter, respectively. The tribological properties of the coated and uncoated samples are investigated using a reciprocating sliding wear tester in NaCl solution. The corrosion performance of the four specimens is evaluated by means of potentiodynamic polarization tests. Finally, the biocompatibility of the various samples is investigated using purified mouse leukaemic monocyte macrophage cells (Raw 264.7). Overall, the results show that the gas-nitriding treatment increases both the hardness and the surface roughness of the samples. Moreover, of the various samples, the Ti-C:H/Ti6Al4V sample exhibits excellent tribological properties and the best corrosion resistance and biocompatibility performance.