Porous nanocrystalline Ti(CxN1 − x) thick films by plasma electrolytic carbonitriding

Nanocrystalline Ti(CxN1 − x) films on titanium were prepared by plasma electrolytic carbonitriding (PEC/N) at 600 V in an electrolytic solution containing triethanolamine and formamide using a pulse power supply. XRD, EDAX, FESEM and TEM were employed to characterize the phase components, element composition, and microstructure of the films. Rockwell C indenter and Vicker’s indentation test were used to evaluate the adhesion and hardness of the films. The obtained results show that the films are porous and composed of Ti(CxN1 − x), without apparent discontinuity in the interfaces adjacent to the titanium substrate. The thickness, ratios of C/N and pores sizes of the films tend to increase with the discharge time. When discharge-treated for 2.5 h, the film is about 15 μm thick and exhibits nanocrystalline characterization with grain size of 40–60 nm. Its hardness is Hv 2083 at the load of 0.2 N and the adhesion, Pc value, is more than 500 N. The formation process and mechanism of the Ti(CxN1 − x) films are discussed.