采用6 kW CO₂激光制备了含10%的TiC-钴基合金熔覆层，通过OM、SEM、EDS、XRD及显微硬度计，研究激光工艺参数对熔覆层显微组织、成分、物相及硬度变化的影响规律。结果表明，熔覆层主要由γ-Co、TiC/(Ti, W)C_1-x、Cr-Ni-Fe-C和少量的 Cr₇C₃相组成，从基体表面到熔覆层表层，组织由细树枝晶→等轴枝晶→细树枝晶，TiC弥散分布于二次枝晶臂根部、顶端或一次枝晶臂上。随激光功率降低或扫描速率增加，熔覆层枝晶含量增加，枝晶间距呈现增大趋势，TiC含量显著增加，尺寸变小，分布更均匀，而TiC形貌从边缘平滑的近圆形向不规则多边形转变，TiC溶解再析出会抑制一次枝晶或二次枝晶生长。实验范围内，随激光功率降低或扫描速率增加，熔覆层表层硬度增加，最高硬度为1246.6 HV_0.2，相对基体提升接近5倍。

The severe wear and uneven wear will happen on the surface of ductile cast iron such as the traction wheel of elevator, in the long-term working under the serious wear and impact conditions. Laser cladding can be applied to reinforce its surface, which can improve the properties and life of the cladded components, save materials and manufacturing cost and raise the economic efficiency, but as to the surface of different materials, especially the ductile cast iron, the alloy powder and process parameters for laser cladding need to be chosen carefully by the experimental studies because of the rapid melting and solidification, the difference of thermo-physical properties between the laser cladding layer and the matrix, the laser absorption of the cladding layer and matrix and so on. In this work, laser cladding is employed to fabricate Co-based composite coatings reinforced by TiC particles by a 6 kW CO₂ laser. The effects of the technical parameters of laser on the composition, phase and microhardness of the laser cladding layer are investigated by OM, SEM, EDS, XRD and microhardness tester, with the emphases of analyzing the changes of the distribution, morphology and size of TiC in the laser cladding layer. It is shown by the results that the cladding layer is mainly composed of γ-Co, TiC/(Ti, W)C_1-x, Cr-Ni-Fe-C and a small amount of Cr₇C₃ phase, and its microstructure changed from the fine dendrite crystal near the cast iron matrix to the equiaxed dendrite in the middle then to the fine dendrite crystal near the surface of laser cladding layer with the dispersed distribution of TiC at the root or tip of secondary dendrite arm, even at the branch of primary dendrite arm. The number of dendrite and the dendrite arm spacing both increase in the microstructure of the laser cladding layer and the morphology of TiC is transformed from the smooth circular shape to the irregular polygon shape, and its content obviously increases with the particle size of TiC decreasing and its distribution more uniform, when the laser power is decreased from 3.6 kW to 3.2 kW or the scanning rate increased from 350 mm/min to 410 mm/min. The growth of the primary dendrite or secondary dendrite can be inhibited by the precipitation of TiC after its dissolution in the melt pool of laser cladding. In this experiment, the hardness at the surface of laser cladding layer gradually increases with the decrease of laser power or the increase of scanning rate, in which the maximal microhardness is 1246.6 HV_0.2, up to increasing by 5 times of the matrix.