目的 在45#钢基体表面制备耐磨性优于基材的梯度涂层。方法 采用激光熔覆技术在基材上制备连接层后，分别用未添加WC颗粒、添加3%和5%WC颗粒的铁基合金粉末制备耐磨涂层。通过金相显微镜（OM）、X射线衍射仪（XRD）、扫描电子显微镜（SEM），研究了涂层的微观结构。通过维氏显微硬度计和M-2000磨损试验机，研究了涂层的力学性能。结果 获得的涂层致密，没有裂纹和气孔等缺陷，涂层内部WC清晰可见。连接层与基材具有良好的冶金结合，涂层组织主要有等轴组织、柱状组织和共晶组织。耐磨层物相组成为奥氏体（γ-Fe）、γ(Fe,Ni)固溶体和Fe-Ni-Cr固溶体。涂层表面的显微硬度最高为559HV1，比基材硬度（182HV1）提升了3倍多。随着WC含量的增加，涂层的磨损量显著下降。结论 基材与连接层有沿基体表面生长的平面晶，涂层内部为柱状晶、树枝晶和共晶等组织，涂层顶部多为细小的等轴晶。加入WC，涂层的显微硬度提高不明显，但WC周围的组织细化，显微硬度提高。无WC的涂层磨损机理主要为粘着磨损；3%WC的涂层磨损较轻，磨损仍以粘着磨损为主；5%WC的耐磨层磨损最轻，磨损机理为磨粒磨损，WC的加入明显提高了涂层的耐磨性。

A gradient coating was prepared on a 45 steel substrate to obtain a coating with better wear resistance than the substrate. After the connection layer was prepared on the substrate by laser cladding, the wear-resisting layer was prepared by using iron-based alloy powders without added WC particles and added 3% and 5% WC particles, respectively. The microstructure of the coating was studied by optical microscope (OM), X-ray diffraction (XRD) and scanning electron microscope (SEM). The mechanical properties of coating were studied by Vickers microhardness tester and M-2000 wear tester. The coating is dense without defects such as cracks and pores, and the WC particles inside the coating are clearly visible. The connection layer and the substrate have a good metallurgical bonding. The coating microstructure mainly has equiaxed, columnar and eutectic structure. The phase of the wear layer is austenite (γ-Fe), γ(Fe,Ni) solid solution and Fe-Ni-Cr solid solution. The average microhardness of the coating is 559HV1 which is more than 3 times higher than substrate (182HV1). As the WC content increases, the amount of wear of the coating decreases significantly. The substrate and the connecting layer have planar crystals grown along the surface of the substrate, and the inner structure of the coating is columnar crystal, a dendrite and eutectic structures, and the top of the coating is mostly a small equiaxed crystals. The addition of WC particles did not significantly improve the microhardness of the coating. The wear mechanism of coating without WC is mainly adhesive wear. The coating wear of 3% WC is light wear and wear is still mainly adhesive wear. The wear mechanism of 5% WC wears the lightest wear mechanism is abrasive wear. The addition of WC can significantly improve the wear resistance of the coating.