稀土对激光熔覆Co基合金组织及性能的影响

为了提高热镀锌生产线关键部件的使用寿命,采用激光熔覆技术在316L不锈钢表面制备了具有不同稀土氧化物含量的Co基熔覆层.利用扫描电子显微镜、能谱仪、X射线衍射仪和显微硬度计研究了稀土氧化物对Co基合金熔覆层显微组织、相结构、显微硬度的影响.结果表明,稀土氧化物使得Co基合金熔覆层的组织更为细化,且硬度更高.添加质量分数为0.5%的CeO_2后,Co基合金熔覆层的显微硬度高达900 HV.Co基稀土合金熔覆层主要由γ-Co、Cr_7C_3及相应稀土氧化物组成.稀土氧化物的加入有效延缓了由锌液沿微裂纹扩展引起的溶解腐蚀.添加质量分数为0.5%的CeO_2后,Co基合金熔覆层的腐蚀深度约为12μm,锌蚀过渡层平直且完整,耐锌蚀性优异.

Effect of rare earth on microstructure and properties of Co-based alloy by laser cladding

In order to improve the service life of key components in hot dip galvanizing production line, the Co-based cladding coating with different contents of rare earth oxide were prepared on the surface of 316L stainless steel with the laser cladding technology. The effect of rare earth oxides on the microstructure, phase constitute and microhardness were investigated with scanning electron microscope(SEM), X ray diffractometer(XRD)and microhardness tester. The results show that the rare earth oxides make the microstructure of Co-based alloy cladding coating finer and its hardness higher. After adding the CeO₂ with the mass fraction of 0.5%, the microhardness of Co-based alloy cladding coating reaches as high as 900 HV. In addition, the Co-based rare earth cladding coatings are mainly composed of γ-Co、Cr₇C₃ and corresponding rare earth oxides. The addition of rare earth oxides can effectively postpone the dissolving corrosion caused by the propagation of molten zinc along the microcracks. After adding the CeO₂ with the mass fraction of 0.5%, the corrosion depth of Co-based cladding coating is about 12 μm, the Zn corrosion transition layer is straight and complete, and the zinc corrosion resistance is excellent.