(中国科学院 半导体研究所 全固态光源实验室，北京 100083)
摘 要: 在304不锈钢(304SS)和Q235碳钢上分别熔覆Ni60A及Ni60A-WC金属粉末，以及添加Cr和Cr3C2的涂层，利用光学显微镜(OM)、扫描电镜(SEM)、能谱仪(EDS)分析涂层的宏观形貌、微观组织和元素分布，用显微硬度计对涂层的硬度进行测试分析。结果表明：基材中元素成分的不同会导致涂层气孔和裂纹的差异，Ni、Cr元素含量高的304SS上的涂层气孔和裂纹数明显比Q235碳钢上的少；基材的导热性能对涂层的稀释率与性能具有明显影响，导热性能差的304SS稀释率大，WC颗粒分解多，涂层组织粗大；由于Q235导热性能好，冷却速率高，导致涂层硬度高，Ni60A+40%WC涂层平均硬度高达1000HV0.2。此外，Cr和Cr3C2的加入能有效防止涂层气孔的产生。
关键字: WC涂层；激光熔覆；显微组织；显微硬度
（Laboratory of All-Solid-State Laser Sources, Institude of Semiconductors,
Chinese Academy of Scienses, Beijing 100083, China）
Abstract:Ni60A and Ni60A-WC laser cladding coatings were prepared on 304 stainless steel and Q235 carbon steel, respectively, as well as adding Cr and Cr3C2 coatings. The macroscopic morphology, microstructure and elemental distribution of the coatings were analyzed by optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The microhardness of the coatings were tested with microhardness tester. The results show that the element composition on the substrate can cause the differences of pores and cracks. The pores and cracks of the coatings on 304 stainless steel (with high contents of Ni and Cr elements) are significantly less than those of the the coatings on Q235 carbon steel. The thermal conductivity of the substrates have a significant impact on the dilution rate and performance of the coatings. Because of poor thermal conductivity, the coatings on 304 stainless steel have high dilution rate, more WC particles decompose and then coarsen the microstructure. The average hardness of Ni60A +40%WC coating on Q235 substrate up to 1000HV0.2 attributes to its good thermal conductivity and high cooling rate. Furthermore, pore free coatings adding with Cr and Cr3C2 are obtained.
Key words: WC coating; laser cladding; microstructure; microhardness
