Setellite21 cobalt-based alloy coating was deposited on 45 steel by electro-spark deposition. Microstructure and phase composition of the coating were analyzed. Wear resistance and wear mechanism of the coating were researched. The results indicate that the coating with compact structure is mainly composed of Co, Co6W6C, CoCx and CoCr. Average microhardness of the coating is 445.34 HV0.5, which is about 2 times to that of the substrate. The coating presents excellent wear resistance with no obvious peelings and scratches. Wear resistance of the coating is about 2.3~2.7 times to that of the substrate. Wear mechanism of the coating mainly contains abrasive wear and fatigue wear, and along with oxidization wear.

Stellite190 cobalt alloy coating was deposited on 45 carbon steel by electro-spark deposition. Formation mechanism, microstructure, phase composition and mechanical properties of the coating were researched, fracture mechanism of the coating was analyzed. The results indicate that, the coating has dense and well distributed microstructure, mainly composed of Co, (CoCrW)6C, Cr7C3. The coating presents excellent mechanical properties with a tensile strength of 731.83 MPa, a bonding strength of 213.01 MPa and good peeling resistance. The mechanism for tensile fracture of the coating is dimple fracture, and for shear fracture is cleavage fracture.

In order to improve the anti-wear and anti-corrosion properties of mechanical parts used in high temperature friction conditions, the Ni-W alloy brush plating coatings were prepared and their tribological properties at elevated environment temperatures were investigated. The results show that the friction coefficients of Ni-W/GCr15 tribo-couples are in the range of 0.168～1.048, which take on the decreasing trend as the increase of environment temperatures. The wear losses of the coatings increase at elevated temperatures, and the critical temperature in which the coatings produce serious wear from slight wear is 250°C. The wear mechanism of the coatings are micro-cutting at room temperature, then it changes into adhesive wear accompanied by a certain of delamination when temperature is high than 250°C. When temperature is higher than 400°C, the main wear mechanism of the coatings is adhesive wear and delamination.

The graphite/CaF2/TiC/Ni-base alloy composite coating was prepared on the surface of 45 carbon steel by plasma spray. Effects of loads, friction counterparts and lubricants on the tribological properties of the composite coating were investigated. The results show that the wear rate of the GCTN composite coating against Si3N4is 0.67×10-3mm3/m, which is about 2 times that against GCr15 steel, because Si3N4induces micro-cutting wear of the composite coating. Water and NaCl solution may induce increasing of friction coefficients and wear rates. Especially, wear rate of the GCTN composite coating in NaCl solution is increased by 3.1 times compared with those under dry sliding and water. The GCTN composite coating presents better anti-wear property than Ni-base alloy coating in different environmental mediums.

In this study, a number of experiments on surface grinding of nanostructured WC/12Co (n-WC/12Co) coatings were conducted on a precision surface grinding machine with a horizontal axis and rectangular worktable. The residual stresses in the as-sprayed and ground n-WC/12Co coatings were measured with the X-ray diffraction method. According to the experimental study and theoretical analysis, this paper investigates the influences of grinding parameters, such as depth of cut, feedrate of workpiece, abrasive grit size and wheel bond type on residual stresses precision grinding of n-WC/12Co coatings.