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采用2 k W半导体激光器在304不锈钢表面进行同轴送粉的激光熔覆Co基合金试验,以提升其表面性能,解决失效问题。通过光学显微镜、扫描电镜、X射线衍射仪研究了熔覆层的显微组织和相结构。采用显微硬度计、摩擦磨损试验机和气蚀装置测试了熔覆层的显微硬度、耐磨性与抗气蚀性。结果表明,Co基合金熔覆层组织均匀、致密,与基体结合良好,没有微观裂纹与气孔等缺陷。熔覆层组织主要由初生γ-Co枝晶固溶体及其间的共晶组织组成,其主要组成相为γ-Co、Fe Ni固溶体、Co Cx和Cr23C6等碳化物。熔覆层最高显微硬度为484 HV0.2,平均显微硬度为474 HV0.2,较基体提高2倍以上;熔覆层的平均摩擦系数和磨损量分别为基体的50.8%和29.2%;熔覆层的抗气蚀性能较基体提高了2.7倍。
A 2 k W semiconductor laser was used to coat the 304 stainless steel surface with a laser cladding Co-based alloy test to improve the surface properties and solve the failure problem. The microstructure and phase structure of the cladding layer were studied by optical microscope, scanning electron microscope and X-ray diffraction. The microhardness, abrasion resistance and cavitation resistance of the coating were tested by microhardness tester, friction and wear tester and cavitation device. The results show that the microstructure of the Co-based alloy cladding is uniform and compact with good bonding with the matrix without microscopic cracks and pores. The microstructure of the coating mainly consists of primary γ-Co dendrite solid solution and the eutectic structure in between. The main phases are γ-Co, Fe Ni solid solution, Co Cx and Cr23C6 carbides. The highest microhardness of the cladding is 484 HV0.2, the average microhardness is 474 HV0.2, which is more than 2 times that of the matrix. The average friction coefficient and wear amount of the cladding are 50.8% and 29.2% of the matrix, respectively. The cavitation erosion resistance of the cladding layer is 2.7 times higher than that of the matrix.