掺稀土的Ni60镍基合金激光熔覆涂层性能的研究
毕业论文关键词：激光熔覆；镍基合金；稀土；显微组织；显微硬度
Abstract It’s easy to appear surface wear and fatigue damage on many engineering materials in the service process, which limits the application condition and scope of materials, reduces the service life of the material. Laser cladding is one of a surface modification technology which achieve rapidly heating and melting of the alloy powder or ceramic powder and the substrate surface under the action of laser beam. And with self cooling, It can formation the coating which has a certain excellent performance of anti abrasion, corrosion resistance and thermal oxidation. What’s more, because of the operation environment is much better and easier to realize automatic operation, it has broad application prospect. The laser cladding of multitrack process meet the people requirements on the preparation of large area and high performance coatings, has become a frontier problem in the field of laser cladding technology. This paper to take the steel 45# as matrix, Ni60, Ni60 + CeO2, Ni60 + Y2O3 powder as cladding materials, preparation containing different percentages of rare earth oxide cladding layer by laser cladding of multitrack process. Through the penetrant inspection of cladding layer, experimental of microstructure observation and microhardness determination to analysis the effect of different content of rare earth oxides on the number of cracks on the surface of coating, microstructure and hardness .In addition, to analysis overlap region of the microstructure characteristics and the hardness variation trend, observed the microstructure and measured the hardness of overlap region. The results show that when added with 0.4% CeO2 can effectively inhibit the coatings showed cracks, grain refinement, maximum improve the microhardness; Y2O3 did not decrease the coating surface crack, but when adding 0.4% Y2O3 coating microhardness and microstructure becomes finer and uniform; in the overlap region, the microstructure has significant changes and microhardness of lap region below other parts of the coating; crystal morphology of the cladding layer with the growth characteristics of directional solidification.
Key words: laser cladding; Ni based alloy; rare earth elements; microstructure; microhardness
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