Microstructure And Properties Of Ti-Si-N Nanocomposite Films Deposited By Magnetron Reactive Co-sputtering

Ti N films are widely applied in abrasive, mechanical, aerospace and other fields because of the high hardness, high wear resistance and high melting points. The properties of these films can be improved through adding other elements such as Al, Si in order to meet the increasing actual needs. In the last decade, Ti-Si-N nanocomposite films have been paying more attention due to their excellent mechanical properties. However, because the optimization of microstructure and properties are not easily attained, the study on preparation process is still of great significance.The Ti-Si-N nanocomposite films were deposited using magnetron co-sputtering, and the effect of power of Si target, negative bias, substrate temperature and N2 flow rate on the microstructures, mechanical and corrosive properties of the Ti-Si-N nanocomposite films were studied by X-ray diffraction(XRD), atomic force microscopy(AFM) Multi-function Test instruments for surface properties of material, nano-indenter electrochemical methods. The experimental results were obtained as follows:The effect of the power of Si target on microstructures and properties of Ti-Si-N nanocomposite films was studied. The results indicate that Si3N4 is amorphous in the Ti-Si-N films. With increasing power of Si target, the preferred orientation was changed from(111) to(200) plane, and the sizes of the Ti N grains in the films first decreased and then increased. The films were more compact and smoother. When the power of Si target increased, the film/substrate adhesion force, nanohardness, elastic modulus and corrosion resistance were improved.The effect of the substrate temperature(100℃~400℃) on microstructures and properties of Ti-Si-N nanocomposite films was researched. The grain sizes of films were smaller at lower temperature, but the surface roughness was larger because there were many large particles present on the surface. As the temperature increased, the average grain sizes of the Ti N crystallites slightly increased and the film surface became smoother and denser. At substrate temperature of 300 ℃, the film/substrate adhesion force and the hardness reached the maximum values of 46 N and 23.0GPa, respectively. Meantime, the corrosion resistance of Ti-Si-N nanocomposite films was the best. When the temperature continued to increase to 400 ℃, the average grain sizes rapidly grew, causing that the mechanical properties and corrosion resistance became poorer.The influence of the negative bias voltage on Ti-Si-N nanocomposite films was investigated. The results show that with increasing negative bias voltage, the Ti N(111) diffraction peak intensity decreased, however the Ti N(200) diffraction peak intensity increased. When the negative bias voltage was-80 V, the surface roughness RMS reached the minimum value of 3.63 nm. The average sizes of the Ti N grains in the films first decreased and then increased. When the negative bias voltage was-120 V, the average sizes reached the minimum value of 8.6 nm. Meantime, the film/substrate adhesion force and the corrosion resistance were the highest, too.The effect of the flow rate of N2 on Ti-Si-N nanocomposite films was studied. The results indicate that the preferred orientation is(200) crystal plane, and the grain size is essentially unchanged, almost independent of the N2 flow rate. And when the flow rate of N2 was 8 m L/min, the surface roughness was the smallest. In this case, the film/substrate adhesion force, the hardness and elastic modulus reached the maximum value of 31 N, 15.8 GPa and 279.2 GPa, respectively, and corrosion resistance of the film was best. But if the flow rate of the N2 is too high, the properties of the films will be reduced instead.