为了研究稀土元素CeO2对激光熔覆涂层性能的影响, 以45#钢为基体、Ni60和Ni60+CeO2粉末为熔覆材料, 采用激光熔覆多道搭接工艺制备了含不同含量稀土氧化物的熔覆层。通过对熔覆层着色探伤、显微组织观察、显微硬度测定的试验, 分析不同含量的稀土氧化物对熔覆层表面裂纹数量、显微组织、硬度的影响规律。结果表明,CeO2的最佳掺杂质量分数为0.004; 适量稀土元素CeO2的掺杂, 可使熔覆涂层裂纹数量减少, 熔覆层的显微组织更加均匀而细小;熔覆涂层表面显微硬度远高于基体, 维氏硬度是基体的3.6倍, 搭接区域硬度值是基体的3倍左右。这表明稀土元素的添加可以抑制裂纹、细化晶粒, 并在一定程度上提高熔覆层硬度。

In order to study effect of rare earth element CeO2 on laser cladding coatings, cladding layers with different contents of rare earth oxides were prepared by laser cladding overlap processing, using 45# steel as substrate, Ni60 and Ni60+CeO2 powder as cladding material. Through experiments of cladding layer dye test, microstructure observation, and microhardness mensuration, effect of different contents of rare earth oxides on cladding layer surface cracks’ number, microstructure, and hardness was analyzed. The results show that the optimal doping mass fraction of CeO2 is 0.004. The crack number of the cladding coating is reduced and the micro structure of the cladding layer is even and tiny with the doping of rare earth element CeO2. The microhardness of the cladding coating surface is much higher than that of the matrix. The Vivtorinox hardness is 3.6 times of that of the matrix. The hardness of the lapping zone is about 3 times of that of the matrix. The addition of rare earth element can restrain the crack, refine the grain and improve the hardness of cladding layer to some extent.