Baohai Yu

Effect of Axial Magnetic Field on the Microstructure, Hardness and Wear Resistance of TiN Films Deposited by Arc Ion Plating

TiN films were deposited on stainless steel substrates by arc ion plating. The influence of an axial magnetic field was examined with regard to the microstructure, chemical elemental composition, mechanical properties and wear resistance of the films. The results showed that the magnetic field puts much effect on the preferred orientation, chemical composition, hardness and wear resistance of TiN films. The preferred orientation of the TiN films changed from (111) to (220) and finally to the coexistence of (111) and (220) texture with the increase in the applied magnetic field intensity. The concentration of N atoms in the TiN films increases with the magnetic field intensity, and the concentration of Ti atoms shows an opposite trend. At first, the hardness and elastic modulus of the TiN films increase and reach a maximum value at 5 mT and then decrease with the further increase in the magnetic field intensity. The high hardness was related to the N/Ti atomic ratio and to a well-pronounced preferred orientation of the (111) planes in the crystallites of the film parallel to the substrate surface. The wear resistance of the TiN films was significantly improved with the application of the magnetic field, and the lowest wear rate was obtained at magnetic field intensity of 5 mT. Moreover, the wear resistance of the films was related to the hardness H and the H3/E*2 ratio in the manner that a higher H3/E*2 ratio was conducive to the enhancement of the wear resistance.

CrN Films Deposited by Magnetic Field-enhanced Arc Ion Plating

CrN films were deposited on high-speed-steel (HSS) substrates by arc ion plating. The influence of an axial magnetic field was examined with regard to the microstructure, chemical elemental composition and mechanical properties of the films. The film chemical composition, microstructure, surface morphology, surface roughness and hardness were investigated by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscope (SEM), Surface morphology analyzer and Viker microhardness test. The results showed that the N/Cr ratio increases when the magnetic field intensity increases from 0 to 30 mT. With increasing the magnetic field intensity, the film structures change in such way: Cr2N+CrCr2N+CrNCrN. The film micro hardness increases with the magnetic field intensity. 1

Effect of Surface Layer Structural-Phase Modification on Tribological and Strength Properties of a TiC-(Ni-Cr) Metal Ceramic Alloy

This paper reports TiC–(Ni–Cr) metal ceramic alloy (ratio of components 50:50) with nanoscaled components formed in the surface layer and smoothly transformed into the initial inner structure throughout the material under pulsed electron irradiation of the alloy surface. Principal changes in the surface layer are ascribed to the formation of gradient structure leading to the increase in wear resistance of the surface layer, drop of friction coefficient and improvement of specimen bending resistance when stressing on the irradiated surface side. The above changes of tribological and strength properties in the surface layer under pulsed electron irradiation become more apparent with increasing atomic mass of a plasma-forming inert gas.