Tribological characteristics of TiN and TiCN hard coatings prepared by pulsed D.C. plasma enhanced chemical vapour deposition

The tribological characteristics of TiN and TiCN hard coatings prepared by pulsed D.C. plasma enhanced chemical vapour deposition were investigated using a pin-on-disk friction and wear tester. The cross-section morphology of the films was observed with a scanning electron microscope, while the phase composition of the films was determined on an X-ray diffractometer. Moreover, the micro hardness of the films was measured on a micro-hardness tester, while the bonding strength of the film to the substrate was determined with an indentation tester and a scratch tester, respectively. The results showed that the ratio of CH₄ in the mixed gas had a great effect on the composition, structure and tribological behavior of the corresponding TiCN film. The TiCN film had higher hardness and better wear-resistance than TiN film. It registered lower friction coefficients and higher interfacial bonding strength than the TiN film as well. This was attributed to the inclusion of C in the film, which led to the formation of TiC and improved the interfacial bonding of the film. 4Cr5MoV1Si is used as raw material of the substrate in the test.