| Plasma surfacing is a commonly used the surface modification technology. By plasma arc heating, the surface of the substrate material formation of molten pool, and feeding way is by synchronizing the melting state of powder into the molten pool. The coating and base material form a good Metallurgical bond coating, and improve the strength, wear ability and corrosion resistance of the material. Usually, the plasma surfacing technology can be used by reason of high temperature. It is the characteristics of low dilution rate. In the automotive, aerospace, metallurgy field is widely used in material surface modification and repair. Improve plasma surfacing process, thus to improve the performance of coatings, has attracted much attention of experts and scholars at home and abroad. Preparation of coating on plasma overlaying welding technology in the process of practice, add a certain amount of rare earth oxides can effectively improve all aspects of the properties of materials, so as to adapt to the working environment more complex. Therefore, this article chose the light rare earth oxide La2O3 as add material, study the La2O3 effect on the microstructure and properties of WC/Ni coating.In this paper. Select Ni and WC pseudo binary eutectic point as material composition proportion, the quality of the WC percentage of 40 wt.%. Studied the influence of plasma surfacing welding process, welding current, welding speed, feeding speed and the welding torch height on the preparation of the coating microstructure, through the study of the metallographic of coating, porosity, scanning electron microscope (SEM), X-ray diffraction (XRD) phase composition analysis, to determine the optimum process parameters of the WC/Ni is:the welding current is 160A,welding speed is 200 mm/min, powder feeding speed is 30 rad/min, welding torch height is 15 mm..On this basis, a certain amount is added to the coating of La2O3 (0.5 wt.%,1.0 wt.%,1.5 wt.%,2.0 wt.%), deal and not deal simple with the best technology parameters to comparison, comparing the difference of microstructure with them. At the same time, choose the best sample performance testing, including:microhardness, friction and wear resistance and electrochemical corrosion resistance. Can be found that, the microhardness, wear resistance and electrochemical corrosion resistance have obvious improvement after adding the rare earth materials. But when continue to increase the amount of rare earth oxides, three kinds of performance has a certain degree of decline. When adding 0.5 wt.% La2O3, coating the microhardness of peaks at 1400 HV; The coating is the least wear weightlessness,0.019 g. When adding 1.0 wt.% La2O3, best the electrochemical properties of coatings, the corrosion potential of-0.802 V, the corrosion current density of 2.771 e-005A·cm-2.Meanwhile, a preliminary analysis in the formation of coating preparation process and the change of thermodynamics in the molten pool. And preliminary discussion the interface, the solubility of coating, the size of the nucleation and growth process of the thermodynamics, it is concluded that the solubility of WC/Ni and nucleation size W element. At the same time, the material size effect and wetting Angle of coating, the combination of reaction by coating the wetting Angle of nucleation process, and the corresponding coating in the growth process.
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