Bio-Tribology and Corrosion Behaviors of a Si- and N-Incorporated Diamond-like Carbon Film: A New Class of Protective Film for Ti6Al4V Artificial Implants

Ti6Al4V artificial implants are increasingly demanded for addressing human dysfunction caused by an aging population and major diseases. However, they are restricted due to the release of vanadium and aluminum ions in the process of corrosion and wear. This work is aimed to provide a protective film for Ti6Al4V artificial implants, and then, a Si-incorporated diamond-like carbon (Si-DLC) film and Si- and N-incorporated DLC (SiN-DLC) film were deposited on the surface of Ti6Al4V by plasma-enhanced chemical vapor deposition. Results suggest that the thickness of the as-deposited DLC film is approximately 2 μm, and the SiN-DLC film shows the lowest surface roughness (53.0 ± 3.6 nm) compared with the Ti6Al4V and DLC films. The above DLC film possesses high mechanical properties compared with Ti6Al4V, and the SiN-DLC film shows the best resistance to plastic deformation. In addition, the DLC film exhibits high adhesive strength (>13 N) with Ti6Al4V, which is a prerequisite for service in liquid environments. Whether in SBF solution or SBF + BSA solution, the friction coefficient and wear rate of the above DLC film are much lower than those of Ti6Al4V, and the SiN-DLC film displays the optimal tribological properties (0.072 and 1.82 × 10^-7 mm³·N^-1·m^-1, respectively). Moreover, Si-DLC and SiN-DLC films possess similar corrosion resistance but are far better than Ti6Al4V. Cytotoxicity test results show that the SiN-DLC film can significantly improve cell viability and promote cell proliferation to a certain extent. Consequently, the SiN-DLC film is a protective film with more potential for artificial implants.