Study Of Fabrication And Properties Of TiAlSiN Composite Coatings Doping C Or WS₂

TiAlSiN coatings have been widely used to increase the lifetime and performance of cutting due to its excellent high temperature properties, but the friction coefficient is very high, so it is necessary to find a effective way to prepare TiAlSiN coatings which not only have high hardness, but also have lower friction coefficient. In this study, TiAlSiN composite coatings on W18Cr4V tool steel with different Si and Al contents were prepared by multi-plasma immersion ion implantation and deposition (MPIIID), TiAlSiCN composite coatings with different C contents were prepared though regulating C₂H₂/(N₂+C₂H₂) content ratios;TiAlSiN/WS₂ mutilayers with different modulation period were prepared by multi-plasma immersion ion implantation and deposition (MPIIID) and unbalanced magnetron sputtering.The chemical composition, microstructure, mechanical properties of these coatings at room temperature and 800℃were investigated by X-ray diffraction (XRD),scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), laser raman spectrum, nano-indentation, scratch and friction tests. Results show that the Si contents can be varied from about 0.64 to 15.8 % through changing the main arc duration time of different cathodes, TiAlSiN composite coatings have a columnar morphology, the maximal intensity of TiN (200) peaks can be found in all patterns, most of the Si and Al element exists as Si₃N₄ and Al₂O₃, the improvement of the mechanical properties of these coatings is obvious with the Si and Al element incorporated, when the Si content increases to 2.33 %, the coating exhibits a hardness of 38GPa. TiAlSiN composite coatings have relative higher friction coefficient and exhibit excellent wear resistance, the improvement of oxidation resistance with the Si and Al element incorporated may attribute to the formation of SiO₂ and Al₂O₃ oxides which inhibit the oxygen diffusion into the deposited TiAlSiN coating. The content of the carbon has important influence on mechanical properties of TiAlSiCN coatings, the hardness and the friction coefficient of the coatings reduced gradually with the increase of carbon content companied with increase of graphite Sp2 bond. Modulation period has important influence on mechanical properties of TiAlSiN/WS₂ coatings. The coating has the highest hardness of 15.9GPa when modulation period was 200nm companied by relative higher friction coefficient. With the increase of modulation period, the coating show low friction coefficient and excellent wear resistance.