A Study On Preparation And Mechanical Property Of CrN Film And Ti-Si-N Nanocomposite Films

In this work, hard films Cr, CrN and Ti-Si-N were deposited on the stainless 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 and wear-resistant experiments were used to test the hardness and wear 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.When the substrate temperature is400℃, Cr target power is450W and the Ar pressure is0.4Pa, the micro-hardness of Cr film is1680Hv.XRD shows that the Cr film have strong (110) preferred orientation.When the substrate temperature is350℃, work pressure is0.6Pa, Cr target power is450W, the Ar pressure is0.4Pa and N2partial pressure is0.2Pa. The micro-hardness of CrN film reaches maximum2100Hv (the main phase is Cr2N). The film has strong Cr2N (111) and Cr2N (110) preferred orientation. When the N2partial pressure is0.1Pa, the friction coefficient of CrN film reached the minimum value of0.23.When the substrate temperature is350℃, work pressure is0.3Pa, Ti target power is400W and Ti-Si target power is560W, the comprehensive property of the Ti-Si-N films(Si content is7.8at%) is best:the micro-hardness is6020Hv, the friction coefficient is0.24(load:25N.revolving speed:20r/min.friction pair:φ4mm. test time:10min). The minimum weight loss of the thin film is0.5mg (load:400g, sand paper:240#, friction times:400).With the increase of Si content, the hardness of Ti-Si-N films is increased at first, and then decreased. At low Si content, the microstructure of the Ti-Si-N films was characterized by a nanocomposite consisting of nano-sized TiN crystallites surrounded by an amorphous Si3N4. With the Si content of5.3at%-9.5at%, part phase of Si3N4exists at crystal state, as the Si content increased (12.5%), amorphous phase of Si3N4is at existence, preferred orientation of TiN grain in the Ti-Si-N film turns TiN (111) to TiN (200).When the Si content was7.8at%, sputter-deposited amorphous Si3N4was forced to crystallize and grow epitaxially with TiN layers when the its thickness was to a critical size, the preferred orientation of the crystallized phase is Si3N4(204), Si3N4(134)and Si3N4(733), the TiN crystallites of initially aligned microstructure became randomly oriented (TiN (111)、 TN(200)、TiN(311)、TiN(220)、TiN(222))and finer.