|
As modern tools and dies coating materials, Ti-Si-N nanocomposite films have attracted great interest due to its high hardness, low internal stress, excellent wear resistance, high cohesion strength between film and substrate material, fine thermal and chemical stability and simple preparation process and all of these advantages of Ti-Si-N films show good conformity with requirements of surface protective treatment of mould and high-speed cutting tools in the field of modern manufacture industry.In this work, hard films Ti-Si-N were deposited on the die steel substrates by a DC reactive magnetron sputtering system. X-ray diffraction, Scanning Electron Microscope, Energy Dispersive Spectrometer and Transmission electron microscopy were used to analysis the phase composition, crystal structure, surface morphology, and elemental composition of thin films. Micro-hardness Tester, wear-resistant experiments and electrochemical workstation were used to test the hardness, wear resistance and corrosion resistance of thin films. By changing the N2partial pressure, substrate temperature and Si content, the properties of hard films were studied, the best process parameters of the films found out, and then studied the sclerosis mechanism of Ti-Si-N film.With the increase of Si content, the hardness of Ti-Si-N films is increased at first, and then decreased. With the Si content of3.8at%～7.6at%, phase of Si3N4mainly exist as amorphous, the microstructure of the Ti-Si-N films was characterized by a nanocomposite consisting of nano-sized TiN crystallites surrounded by an amorphous Si3N4.The grain size of TiN is decreased with the increase of Si content, reduced to8nm when Si content is7.6at%and nitrogen partial pressure is0.03Pa, meanwhile, the preferred orientation of the crystallized phase is TiN (111), and the thickness of amorphous Si3N4layers increased to a critical size (0.3～0.5nm).Under the influence of its thickness, diffraction peak of crystal face (111),(200),(311),(220) and (222) of TiN broadened. When the substrate temperature is300℃, nitrogen partial pressure is0.03Pa, work pressure is0.22Pa, Si content of Ti-Si target is8m%and Ti-Si target power is450W, the comprehensive property of the Ti-Si-N films(Si content is7.6at%) is best:the micro-hardness is4954Hv, the friction coefficient is0.07(load:25N, revolving speed:20r/min, friction pair:Φ4mm, test time:10min). The minimum weight loss of the thin film is0.2mg (load:400g, sand paper:240#, friction times:800). The corrosion resistance of films is good, its corrosion current is only2.434X10-6A and AC impedance achieved104order of magnitude,
|