The Effect Of Heat Treatment On Microstructure And Performance Of Ni-WC Coating Formed By Vacuum Fusion Sintering

Made Ni-base alloy tungsten Carbide composite coating with 1.0 percent CeO₂ content and without CeO₂ on 45 steel by the way of Vacuum fusion sintering. Then we disposed the samples with normalizing, quenching and tempering. After those hot treatments, first, we observed the coating's microstructure by Optics Microscope (OM),then observed and measured the histology of alloying-coating, diffusion horizon and matrix by Scanning Electron Microscope (SEM) and Energy-Dispersive Spectrometer (EDS). After that, we also measured the samples' hardness, wear-resisting property and bond strength by Rockwell hardometer, microhardness instrument, abrasion machine and fatigue testing machine. The results showed that:(1) Different heat treatments had little influence on the coatings, but it had much influence on the matrix. There was diffusion layer between the coating and matrix, which was a white light area, and heat treatments widened the diffusion layer.(2) Adding 1.0 percent CeO₂ changed the shape and distribution of WC,WC became smaller and distributed uniformly, made it fused with nickel-base alloy better, this made the quality of coatings improved more.(3) Different heat treatments did little effect on the coatings' surface hardness, but it improved the hardness of matrixes in a large scale. The coatings' longitudinal microhardness assumed as "the mountain" shape distribution, the microhardness of the coatings with 1.0 percent CeO₂ was higher than that without CeO₂.(4) Different heat treatments almost had no influence on the bond strength between coatings and matrixes. But the bond strength of samples with 1.0 percent CeO₂ was larger than that without CeO₂.(5) Different heat treatments improved the wear resistance of the coatings and wear resistance of the coatings with 1.0 percent CeO₂ was better than that without CeO₂.