Friction and Wear Characteristics of Nano-Structured Ti-Si-N Films on a High Speed Steel Substrate

TiSiN nanocomposite thin films composed of nanocrystalline TiN and nanosized amorphous Si3N4 were deposited on a high speed steel substrate by pulseddirect current plasma enhanced chemical vapor deposition at 550 ℃ on an industrial setup, by properly adjusting the mixing ratio of the chlorides as the starting materials to control the compositions of the films. The friction and wear behaviors of the TiSiN nanocomposite films sliding against SAE52100 steel at ambient temperature and 400 ℃ were comparatively investigated with that of TiN film on a ballondisc friction and wear tester. The microstructures and compositions and chemical features of the films were analyzed by means of scanning electron microscopy, transmittance electron microscopy, Xray diffraction, and Xray photoelectron spectroscopy. It was found that the Si content of the films was ranged from 0% to 35at.%. The deposition rate of the films increased with increasing Si content, while the grains size coarsened therewith. The TiSiN films had a grain size ranged within 750 nm and showed much higher microhardness and much better wearresistance than the TiN film, though they recorded large friction coefficients (about 0.8 at room temperature and 0.7 at 400 ℃). Moreover, the TiSiN films of larger Si ontents had relatively poor wearresistance than the ones of smaller Si contents, which could be attributed to the enhanced grain size coarsening of higher content Si of poor electric conductivity.