Tribological, electrochemical and biocompatibility properties of Ti6Al4V alloy produced by selective laser melting method and then processed using gas nitriding, CN or Ti-C:H coating treatments

Ti6Al4V alloy samples prepared by selective laser melting (SLM) were nitrided at a high temperature of 900 °C and then coated with amorphous carbon nitride (CN) or DLC-doped Ti (TiC:H) thin films using a closed field unbalanced magnetron sputtering (CFUMS) system. The microstructures, mechanical properties and coating adhesion strengths of the various specimens were evaluated by X-ray diffraction, nanoindentation tests and Rockwell hardness tests, respectively. The tribological properties of the samples were examined in 0.89 wt% NaCl solution by means of reciprocating sliding wear tests performed against 316L, Si3N4 and Ti6Al4V balls under a load of 10 N for 1440 s. In addition, the corrosion properties were evaluated by potentiodynamic polarization tests. Finally, cytotoxicity tests were performed using mouse leukemic monocyte macrophage cells (Raw 264.7) for culture periods of 1, 3 and 5 days, respectively. Overall, the Ti6Al4V sample processed using a duplex nitriding and DLC coating treatment exhibited a good coating adhesion, the highest wear resistance, the best corrosion resistance and excellent biocompatibility.