Effect of substrate bias on biocompatibility of amorphous carbon coatings deposited on Ti6Al4V by PECVD

Long service life of implants is of high importance to patients. This study deposited amorphous carbon (a-C) coatings on biomedical grade Ti6Al4V substrate using plasma-enhanced chemical vapor deposition (PECVD). The effect of substrate bias power on microstructure and corrosion of the coatings is investigated and compared with the bare Ti6Al4V substrate. The experimental results show that the substrate bias power of 30 W leads to amorphous carbon in microstructure. With increased bias nanocrystalline graphite appears. All coated samples have significant improvements in corrosion resistivity as compared to Ti6Al4V alone. The sample deposited at bias power of 30 W with a thickness of 150 nm demonstrated the lowest corrosion current of 6.47 nA/cm2 and the lowest corrosion rate of 8.05 nm/year, which can postpone the corrosion of the Ti6Al4V substrate for at least 18 years. From the in-vitro cell culture studies, the best sample also registered the higher cell viability and biocompatibility as compared to bare Ti6Al4V, thus could be helpful in promoting healing.