激光熔覆Ni/TiB_2复合涂层的组织与性能研究

Microstructure and performance of laser cladding of Ni/TiB_2 composite coatings

在45钢表面利用激光熔覆技术制备了Ni/TiB_2金属陶瓷复合涂层,利用光学显微镜、扫描电子显微镜、能谱仪、显微硬度计等,分析了涂层的显微组织特征、元素的分布以及涂层的机理等,并对试样硬度进行了测定。结果表明,在合理的工艺参数下,超细TiB_2的加入,细化了激光熔覆涂层的晶粒,熔覆层显微组织主要由细小的等轴晶组成,TiB_2陶瓷颗粒分布在枝晶间,而分解后的Ti均布于枝晶内,通过细晶强化、固溶强化及第二相强化等,大大提高了涂层的硬度。

The metal-ceramic composite coatings of Ni/TiB_2 have been attained by laser cladding on 45~# carbon steel. The microstructure and distribution of the elements in the cladded coating and the mechanism of the coatings to form are analyzed with OM, SEM and EDS, and the micro-hardness along with the depth is measured. Results show that the microstructure of the cladded coatings are mainly fine equal-axis grains, growth of which is inhibited under sound process parameter with added ultrafine powder of TiB_2. TiB_2 distribute around the γ-Ni dendrites and Ti are in the dendrites. The hardness of coatings which have been reinforced by small grains, solid solution mechanism and second phase have been improved.