Preparation and Characterization of Micro-Arc Oxidation Coating and Carbon Film on Titanium

To increase the binding force between titanium substrate and carbon film and enhance the protective properties of the coatings, a titanium oxide coating structure with metallurgical bonding for the substrate was prepared using micro-arc oxidation (MAO) technique, and then a carbon film was deposited using ion beam deposition combined magnetron sputtering technique on the titanium oxide coating to obtain a duplex coating. Microstructure and properties of the film-based systems were comparatively studied by SEM equipped with EDS, AFM, wear test and electrochemical experiment. Results show that the surface carbon film could not completely cover the micropores of the MAO coating, and the MAO titanium oxide coating on Ti substrate has porous features, which effectively increases the binding force between the top carbon film and the Ti substrate. The Ti substrate/MAO coating/carbon film system has the lowest friction coefficient, the lightest fluctuation and the smallest width of wear scar in the process of friction, showing the excellent tribological performance. However, the corrosion resistance of the newly designed composite coating is worse than that of the Ti substrate/Ti interlayer/carbon film. This is related to a thin carbon film and porous characteristics of MAO coating of the composite coating, because the corrosion medium easily enters the interface between the carbon film and MAO coating through the micropores, thus reducing the resistance corrosion. © 2020, Science Press. All right reserved.