Preparation of Ti(C_xN_1-x) thick films on titanium by plasma electrolytic carbonitriding

Porous nanocrystalline Ti(C_xNi_1-x) thick films firmly bond to the substrate were obtained on commercial pure titanium by plasma electrolytic carbonitriding (PECN). The evolutions of the inicrostructure and phase composition of the PECN modified film with the treatment time were investigated. The results show that the thickness, ratio of C/N and pores size of the film tend to increase with the discharge time. When discharge-treated for 150 min, the film is about 15 μm in thickness and exhibits nanocrystalline characteristic with a grain size range of 40-60 nm. The TiH₂-riched layer induced by the permeation of hydrogen during the PECN locates beneath the film, and it can be completely removed by subsequent vacuum annealing treatment while the composition and surface morphology of the Ti(C_xN_1-x) film keep unchanged.