大面积激光熔覆制备原位自生TiB_2-Ni金属陶瓷复合涂层的研究

In Situ Synthesis of TiB_2 Ni Metal Ceramic Composite Coating by Large Area Laser Cladding

利用多道搭接激光熔覆技术,在 45钢表面制备出原位自生TiB2颗粒增强Ni基金属陶瓷复合涂层,可以实现金属基体的高韧性与陶瓷材料优异性能的良好结合,改善材料表面性能。采用XRD,SEM对涂层的组织结构进行了研究。结果表明:多道搭接涂层主要由γ (Ni, Fe)粘接金属基体和以TiB2为主的原位析出硬质颗粒组成。B, Ti, Ni, Fe元素在涂层中基本呈均匀分布,涂层最表面Ti稍有富集。涂层组织是由γ (Ni, Fe)先共晶奥氏体枝晶及晶间TiB2 /γ (Ni, Fe)共晶组成。熔覆搭接区以马氏体相变方式冶金结合。熔覆层与基体及各道熔覆层之间界面结合良好。

Ni based metal ceramic composite coating reinforced by in situ synthesized TiB_2 particles was fabricated on AISI1045 steel substrate making use of overlapping laser cladding, so as to improve the surface properties of the steel by integrating the high ductility of the metal matrix with the excellent mechanical properties of the ceramic reinforcement. The resulting composite coating was characterized by means of scanning electron microscopy and X ray diffraction. It was found that the Ni based composite coating mainly consisted of γ (Ni, Fe) bonding metal matrix and the (in situ) synthesized TiB_2 hard particulates. The element B, Ti, Ni, and Fe were almost homogeneously distributed in the composite coating, while Ti was slightly enriched on the superficial layer of the coating. The composite coating was composed of the advanced austenite dendrite of γ (Ni, Fe) and intergranular TiB_2/γ (Ni, Fe) eutectic in terms of the microstructure. The cladding layers and the matrix and the inter cladding layers had strong interfacial bonding, which was attributed to the metallurgical bonding in the overlapped cladding area where martensite transformation occurred.