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采用预涂激光熔覆技术,在A3钢表面制备原位生长Cr3C2-CrB复合增强镍基激光熔覆层。使用金相显微镜、扫描电镜(SEM)、能谱仪(EDS)和X射线衍射(XRD)仪对熔覆层进行了显微组织和物相分析,并测试了熔覆层显微硬度及摩擦性能。结果表明,在适当工艺条件下,熔覆层成形良好、表面光滑,涂层与基体呈现良好的冶金结合。熔覆层底部组织为包含Cr,Fe的碳、硼化物的γ(NiFe)树枝晶结构。熔覆层中上部组织为先共晶析出、规则排列的Cr3C2杆状相和CrB颗粒相分布在Fe2C/γ(NiFe)共晶基体中。由于Cr3C2-CrB复合强化相的原位生成且均匀弥散分布在基体中,使得熔覆层具有高的硬度(平均硬度HV0.31100)和良好的耐磨性,其磨损失重仅为纯Ni60熔覆层的1/3。
In-situ growth Cr3C2-CrB composite reinforced Ni-based laser cladding layer was prepared on the surface of A3 steel by pre-coating laser cladding technology. The microstructure and phase analysis of the coating were investigated by metallographic microscope, scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD). The microhardness and friction performance. The results show that under suitable conditions, the cladding layer is well formed and the surface is smooth, and the coating and the substrate exhibit good metallurgical bonding. The bottom of the cladding is a γ (NiFe) dendritic structure containing Cr and Fe carbon and boride. The upper structure in the cladding layer is eutectic first, and the regular arrangement of Cr3C2 rod-shaped phase and CrB particles is distributed in the Fe2C / γ (NiFe) eutectic matrix. Cr3C2-CrB composite strengthening phase generated in situ and uniformly dispersed in the matrix, making the cladding layer has a high hardness (average hardness HV0.31100) and good wear resistance, the wear loss is only pure Ni60 cladding 1/3 of the floor.