Synthesis and evaluation of TaC nanocrystalline coating with excellent wear resistance, corrosion resistance, and biocompatibility

To improve the mechanical properties, corrosion resistance, and biocompatibility of implanted titanium alloys, a TaC nanocrystalline coating was deposited on Ti–6Al–4V alloy using a double-cathode glow discharge method. The microstructure of the newly developed coating was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The coating exhibits a dense and uniform structure, composed of equiaxed TaC grains with an average grain size of 15.2 nm. The mechanical properties of the TaC-coated Ti–6Al–4V alloy were evaluated by a scratch tester, a nanoindentation tester, and a ball-on-disc tribometer. The average hardness of the TaC nanocrystalline coating is about 6 times higher than that of uncoated Ti–6Al–4V alloy and the specific wear rate of the coating is two orders of magnitude lower than that for Ti–6Al–4V at applied normal loads of 4.9 N under dry sliding condition. The electrochemical behavior of the TaC nanocrystalline coating after soaking in Ringer's solution for different periods was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Furthermore, in vitro cytocompatibility of the coating was assessed using MC3T3-E1 mouse osteoblastic cells. The results showed that the TaC coating exhibits better corrosion resistance and biocompatibility as compared to uncoated Ti–6Al–4V alloy.