应用稀土及激光熔覆工艺制备钴基合金梯度涂层

Formation of gradient coating of Co-based alloy with rare earth by laser cladding

采用稀土变质及激光熔覆工艺在 2 0号钢基体上获得了钴基自熔合金梯度组织涂层。结果表明 ,2 0 4Co合金涂层组织为均匀的亚共晶 ,其组成相包括ε Co ,Co3 B ,M2 3 (C ,B) 6,Cr2 B及Co7W6化合物 ,平均硬度为HV10 70 ,比基体 (HV180 )高HV890 ,耐磨性与基体相比提高 1.5倍。在 2 0 4Co合金中加入 0 .6 %的稀土 ,可以获得梯度涂层。其组织由亚共晶向共晶连续过度 ,与前者相比 ,组成相增加了CeCr2 B4 ,最高硬度达HV12 0 4,比原合金高 12 .3%,耐磨性与基体相比提高近 2倍 ,比原合金提高了 2 5 %。

A method was approached about making a gradient coating of self-melt Co-based alloy on 20 steel substrate with rare earth(RE) by laser cladding. The results show that the coating with 204 Co alloy is a homogeneous sub-eutectic structure, which consists of ε-Co, Co 3B, M 23(C, B) 6, Cr 2B and Co 7W 6. The average hardness is HV1?070, HV890 higher than that of the substrate (HV180). And the wear resistance of the layer is found to be increased 1.5 times that of the base. When 0.6% RE is added into the 204Co alloy, the coating microstructure reveals a gradient variation with the layer depth. The microstructure varies continuously from sub-eutectic to eutectic. Apart from the phases contained in the 204Co coating above, this coating still contains CeCr 2B 4. The highest hardness of the coating is HV1?204, increasing 12.3% than that of 204Co alloy. The wear resistance is found to be increased about 2 times than that of the base and to be 25% higher than that of the 204Co alloy. The mechanism of forming gradient structure was discussed