为了分析激光功率对Co基梯度耐磨涂层组织和性能的影响, 采用激光熔覆在20CrMnMo钢表面依次熔覆St6, St12B, Co47+WC(质量分数为0.05)合金粉末制备厚度约为2.4mm的Co基梯度耐磨涂层, 进行了微观组织分析、显微硬度测试、摩擦磨损试验。结果表明, 不同激光功率下涂层表面均没有出现裂纹且各涂层中晶体形貌相似, 表层出现致密的等轴晶、过渡层出现粗大的柱状晶、底层出现平面晶和树枝晶; 600W时耐磨层中发现未熔WC颗粒, 800W耐磨层发现CoW2B2硬质相; 在600W～800W范围内, 激光功率越高, 涂层整体的显微硬度和耐磨性越好; 激光功率为800W时, 耐磨层显微硬度达到730HV0.1, 涂层耐磨性相对于基体提高了300%。此研究结果对激光熔覆制备Co基梯度耐磨涂层提供了参考依据。

In order to analyze effect of laser power on microstructure and properties of Co-based gradient wear-resistant coatings, alloy powders of St6, St12B and Co47+WC (mass fraction of 0.05) were claded on the surface of 20CrMnMo steel. Co-based gradient wear-resistant coatings with the thickness of about 2.4mm were prepared to do microstructure analysis, microhardness test, friction and wear test. The results show that there is no crack on the surface of the coatings under different laser powers. The morphology of the crystals in each coating is similar: dense equiaxed grains in the surface layer, large columnar crystals in the transition layer, and plane and dendrites in the bottom layer. The unmelted WC particles are found in the wear-resistant layer at 600W. The hard phase of CoW2B2 is found in the wear-resistant layer at 800W. From the study about the properties of the coatings, the higher the laser power, the better the microhardness and wear resistance of the coatings in the range of 600W to 800W. When laser power is 800W, microhardness of the wear-resistant layer is 730HV0.1, and wear resistance of the coating is 300% higher than that of the matrix. The results of this study provide a reference for the preparation of Co-based gradient wear-resistant coatings by laser cladding.