Multiphase nanocomposite thin films composed of nanocrystalline TiN, nanosized amorphous Si3N4, and occasionally amorphous or nanocrysralline TiSi2, were deposited on high-speed steel substrate at 550 1C, using an industrial setup of pulsed-d.c. plasma-enhanced chemical vapor deposition technique. Feed gases used were TiCl4, SiCl4, N2, and H2. The composition of the films could be controlled well, through adjustment of mixing ratio of chlorides. The Si contents in films varied in the range 0-35 at%. It was found that Si contents in coatings play a great role on the quality of Ti-Si-N coatings. Ti-Si-N coatings of high Si contents were less dense than that of low Si contents. Ti-Si-N coatings with coarse grains show poor adhesion to substrates and high electrical resistance. The results indicated clearly that wear-resistant properties of TiN coating remarkably increase with addition of silicon, while friction coefficient remains high (about 0.8) at room temperature and reduces only slightly at elevated temperature (about 0.7 at 400℃). There was a much lower wear resistance in higher-Si-content films due to coarse mirostructure during formation of coating.

Superhard nanocomposite nc-TiN/a-Si3N4 coatings were prepared by reactive magnetron sputtering (RMS) and pulsed dc plasma-induced chemical vapour deposition (PCVD) on stainless steel substrates. The tribological behaviour of these coatings at room and elevated temperature was compared with that of TiN coatings deposited by RMS and PCVD. The results show that the superhard nanocomposite nc-TiN/a-Si3N4 coatings have a somewhat higher friction coefficient of 0.55-0.7 at room temperature that decreases to about 0.4-0.5 at 550 ℃. However, the friction coefficient of pure TiN coatings is 0.6 at room temperature and increases to 0.7 after a sliding distance of 0.1 km at 550℃.

The possibility of surface modification on dyes and tools is investigated with pulsed d.c. plasma enhanced chemical vapor deposition PECVD.on an industrial scale. The effects of pulsed parameters such as pulsed voltage and pulsed frequency on the performance of the coated samples are analyzed based on mechanical testing and microstructural examinations. The tested samples are titanium nitride film coated on steels and cemented carbides. Experiments indicate that the inner-wall of the holes can be coated with the aid of pulsed d.c. plasma, and the quality of coatings depends to a great extent on the pulsed parameters. The adhesion strength characterized by the critical force in indentation test can be increased over 1000N on the high-speed steel substrate when the processing condition is optimized, and the processing procedure plays an important role in the pulsing deposition.

Ti-6Al-4V alloy has been used with some success in orthopedic devices and other engineering components due to several beneficial properties. However, inadequate wear behavior of Ti-6Al-4Valloy has largely restricted fields of application for this material. In this paper, a new method of plasma nitriding and plasma-enhanced chemical vapor deposition (plasma-duplex process) was conducted on Ti-6Al-4V alloy in order to modify its wear performance. The results indicate that the plasma nitriding processing temperature plays a dominant role in nitrided layer formation when compared to other nitriding parameters (e.g. treatment time, gas flow ratio of H2/N2 etc.). It is also shown that plasma nitriding and TiN coatings produced by plasma-duplex processing provide a marked improvement in the wear performance of the modified Ti-6Al-4V alloy surface. However, the friction coefficients of plasma-duplex treated samples increased significantly compared to the substrate. There is also a negative effect on the wear behavior if the TiN coating adhesion is poor.

In order to design coatings with optimized wear and corrosion performance, knowledge of residual stress in hard coatings and its dependence on the processing parameters is required. In the present paper, TiN coatings deposited onto tool steels using pulsed d.c. plasma enhanced chemical vapor deposition were investigated. The processing parameters, including pulse voltage, pulse frequency and pre-nitriding time were varied. The residual stress was measured with X-ray diffraction and the interfacial adhesion between the coating and the substrate was evaluated using both indentation test(Pc)and scratch test(Lc). It was found that the residual stress and the adhesion could be adjusted by the processing parameters, and a correlation between these two properties was established. It was also evident that the residual stresses in coating deposited in the industrial-scale pulsed d.c. plasma CVD facility were much smaller than in those deposited in a conventional laboratory-scale chamber with d.c. power.