目的 优化激光路径填充方式以减少皮秒加工圆凹坑底部的堆积现象，并探究基于该激光路径填充方式的皮秒激光关键参数对Ni60/WC涂层表面圆形凹坑形貌参数的影响规律。方法 采用搭建的紫外皮秒激光微加工平台在Ni60/WC涂层表面加工预先规划的直径为230 μm的圆凹坑，通过白光干涉仪测试加工所得圆凹坑的整体三维形貌对圆凹坑底部形貌进行表征。采用同心圆网格复合激光路径填充方式对圆凹坑底部堆积现象进行优化，并通过单因素法分析该路径下皮秒激光关键参数，即加工功率、扫描次数、扫描速度对圆形凹坑深度、直径和圆度系数的影响规律。结果 通过优化的同心圆网格复合激光路径填充方式加工所得圆凹坑材料去除体积为7.59×10⁶ μm³，轮廓算术平均高度为21.37 μm，对比原始的网格激光路径填充方式，加工的圆凹坑底部无明显堆积;基于此激光路径填充方式，在测试工艺参数范围内，圆凹坑深度、直径和圆度系数随激光功率的增大呈二次函数增大;随着扫描速度的增大，圆凹坑深度、直径呈线性减小，圆度系数呈线性增大;圆凹坑深度、直径和圆度系数随扫描次数的增加均呈线性增大。结论 同心圆网格复合激光路径填充方式可以有效改善Ni60/WC涂层表面皮秒加工圆凹坑底部堆积现象，针对直径(230±5) μm、深度(30±5) μm的圆凹坑，优选出的皮秒激光加工参数范围为:激光功率6~7 W，扫描速度6 000~8 000 mm/s，扫描次数1~2次。

Recent studies show that surface texture with reasonable parameters can improve tribological properties of materials and prolong the service life of machinery. Laser ablation of dimples on the surface of Ni60/WC coating of fracturing pump plunger is an effective means to improve the lubrication and wear resistance of the plunger-root seal system. However, the accumulation at the bottom of the dimples produced by the current grid filling method is serious, which is not conducive to the improvement of wear resistance of the plunger coating by dimples. In order to optimize the filling methods of laser path and reduce the accumulation at the bottom of dimples in picosecond machining, the effect of key picosecond laser parameters on the surface of Ni60/WC coatings under this path on the shape parameters of dimples was investigated. A dimple with a diameter of 230 μm was planned on the surface of the Ni60/WC coating through the built picosecond processing platform and the ultraviolet picosecond laser micro-processing platform. The bottom morphology of the dimple was characterized by the 3D morphology obtained by white-light interferometer test. The concentric grid composite filling method was used to optimize the stacking phenomenon at the bottom of dimples, and the single factor method was used to analyze the effect of picosecond laser processing power, scanning times and scanning speed on the depth, diameter and roundness coefficient of dimples. The results showed that the removal volume of dimple materials obtained by the optimized concentric circle grid filling method was 7.59×106 μm3, and the arithmetic average height of contour was 1.37 μm, which showed no obvious accumulation compared with the original grid filling method. Based on the filling path, the depth, diameter and roundness coefficient of the dimples increased as a quadratic function with the increase of laser power within the testing parameters. With the increase of the scanning speed, the depth and diameter of dimples decreased linearly, while the roundness coefficient increased linearly. The depth, diameter and roundness coefficient of dimples increased linearly with the increase of scanning times. In conclusion, the concentric circle mesh composite filling method can effectively improve the accumulation phenomenon at the bottom of dimples during picosecond machining of Ni60/WC coating surface. For the dimples with diameter of (230±5) μm and depth of (30±5) μm, the optimal range of picosecond laser processing parameters is as follows:the laser power is 6-7 W, the scanning speed is 6 000-8 000 mm/s, and the scanning times are 1-2 times. This study optimizes the picosecond laser bottom stacking of Ni60/WC coating material with dimple texture parameters arranged on the surface, and optimizes the laser processing range. In this study, the key parameter evaluation method of picosecond laser processing for designing texture parameters of dimples on the surface of Ni60/WC coating material is preliminarily formed, which lays a foundation for industrial processing of optimum texture on Ni60/WC coating surface by laser beam splitting technology.