中文摘要：

为改善汽轮机叶片性能,利用5 kW CO2激光器在汽轮机末级叶片表面制备NiCrBSiCoWC涂层,利用SEM观察熔凝层组织,利用HB1000B维氏硬度计测试熔凝层显微硬度,在XP-5数控高温摩擦磨损试验机上进行磨损试验,分析影响叶片熔凝层开裂行为的因素。实验结果表明：激光熔凝层与基材形成良好的冶金结合,熔凝层组织均匀,当熔凝层厚度为0.2～0.3 mm,基材预热至220℃时,熔凝层裂纹宽度和长度能得到有效控制,熔凝层平均硬度约为964 HV,其耐磨性比基体有明显的提高,熔凝层磨损后表面平滑,磨损体积减少约89%。

英文摘要：

To improve the mechanical properties of the last-stage steam turbine blade,NiCrBSiCoWC coating on the surface of the turbine blade was carried out at first by using CP-3000 multiple functional flame sprayer and then by 5 kW CO2 laser for melting-cladding the sprayed coating.The morphologies and micro-hardness of NiCrBSiCoWC layer were investigated by SEM and hardness tester HB1000B.Wear-resistance was tested on XP-5 high-temperature wearing tester,and the effect factors on the cracking behavior of cladding layer was analyzed.The results show that adhesion between the laser melting-cladding layer and the substrate is good,and microstructure of the layer is homogenous.When coating thickness and temperature of substrate are appropriate,the width and length of cracks on the surface of the cladding layer can be effectively controlled.The average hardness of the coating is 964 HV and wear-resistance is higher than that of the substrate.The wear volume of the NiCrBSiCoWC clad turbine blade reduced by 89%.