Microstructure, corrosion resistance and biocompatibility of titanium incorporated amorphous carbon nitride films

Titanium incorporated amorphous carbon nitride films were deposited by direct current magnetron sputtering. The films change from amorphous to nanocomposite structure, the relative fraction of sp3 C–N bonding decreases significantly from 2.17 to 1.64 with the increase of Ti content from 2.7 at.% to 12.3 at.%. For the films with high Ti content, the nanocrystalline TiN embedded in a-CNx matrix, while principally TiN did not appear to be well formed for the film containing low Ti content. Potentiodynamic polarization, in vitro human osteoblasts and murine fibroblast cell adhesion tests were employed to assess the corrosion performances of Ti6Al4V alloy coated with the films in Tyrodeʹs solution, and the biocompatibility of Ti-incorporated a-CNx films, respectively. Titanium incorporation increases the corrosion resistance of a-CNx films, and the higher corrosion potential and lower corrosion current density are observed for the alloy coated with the film containing lower Ti content. The high osteoblast adhesion and activation demonstrate the enhanced biocompatibility of Ti alloy coated with Ti-incorporated a-CNx films. The improved biocompatibility in biological environment is attributed to structural change after titanium introduction.