氧化铝增强镍基涂层的激光熔覆合成研究

Research on Laser Cladding Synthesis of Nickel-Based Coatings Reinforced with Alumina

摘要: 高强韧性车钩是连接列车和车辆平稳行驶的保证。因此，本文通过激光熔覆工艺在车钩基体表面制备高强韧性的氧化铝增强镍基复合涂层，并通过扫描电镜和透射电镜和EBSD分析了熔覆层的结构、成分及微观组织。结果表明，在激光熔覆过程中，液态金属流动场可以打碎粗大的树枝晶并细化晶粒，而且Al₂O₃硬质相加剧了流动场的流动性，进一步细化了晶粒并改变了树枝晶的生长方向，从而在熔覆层中形成了尺寸细小的晶粒组织；激光熔覆镍基复合涂层的显微硬度是基体显微硬度的2.31倍，预示该涂层具有良好的力学性能。本文的研究结果将为高强韧化车钩设计提供很好的理论指导。

Abstract: High strength and toughness coupler is the guarantee to connect the train and the vehicle running smoothly. Therefore, in this paper, a high-strength and toughness alumina reinforced nickel-based composite coating was prepared on the surface of the coupler substrate by laser cladding process, and the structure, composition and microstructure of the cladding layer were analyzed by scanning electron microscopy, transmission electron microscopy and EBSD. The results show that during the laser cladding process, the liquid metal flow field can break the coarse dendrites and refine the grains, and the Al₂O₃ hard phase aggravates the fluidity of the flow field, further refines the grains and changes the growth direction of the dendrites, thus forming a fine grain structure in the cladding layer. The microhardness of the laser cladding Ni-based composite coating is 2.31 times that of the substrate, indicating that the coating has good mechanical properties. The research results of this paper will provide good theoretical guidance for the design of high-strength and toughness couplers.