Deposition of diamond-like carbon films containing metal elements on biomedical Ti alloys

Three kinds of diamond-like carbon (DLC) films, which contain different metals (Ti, Cr, Zr) and different interface designs, were deposited on biomedical titanium alloy (Ti–6Al–4V, ASTM F136) by using a cathodic arc evaporation system. Preliminary results showed that the DLC films are hydrogenated, amorphous and dense in structure. Scratch tests and Rockwell indentation tests reveal that the graded structures can improve the adhesion of DLC films. The Raman analyses showed that the Cr-containing DLC films possess lower ID/IG ratio, lower G-peak positions, and higher coating hardness. The pin-on-disk wear test in different environments (air and simulated body fluid) revealed that all the DLC films improve the wear performance of the substrates, and the wear coefficient is lower in simulated body fluid than that in air. In addition, the Cr-containing DLC films exhibited the lowest friction coefficient of 0.06 in simulated body fluid and 0.16 in air with the counterface of UHMWPE. Because of their dense structure, good adhesion and superior corrosion resistance in SBF, the Cr-C:H/CrN films exhibited significantly low friction in SBF. The ICP-MS analysis revealed the release of Cr ion is 2.22–10.03 ppm from the Cr-contained DLC films, which is less than that from Co–Cr–Mo alloy (106.17 ppm), showing that the Cr-containing DLC films meet the requirement of biomedical applications. The potentiodynamic test revealed that the corrosion resistance of the ASTM F136 titanium alloys is increased substantially by the metal-containing DLC coating.