目的 研究不同粒径微米金刚石对Ni-P金刚石化学复合镀层摩擦磨损性能的影响。方法 选择出一组优良的Ni-P化学镀工艺参数，在镀液中分别加入不同粒径的金刚石微粒，制备含不同粒径微米级金刚石颗粒的化学复合镀层。用SEM和XRD，观察并分析了不同粒径金刚石对热处理前后Ni-P金刚石化学复合镀层微观形貌和组织结构的影响；通过硬度和摩擦磨损实验，研究了不同粒径金刚石颗粒对复合镀层硬度及摩擦磨损性能的影响。结果 制备的复合镀层厚度为30 μm左右，金刚石质量分数达到21%~25%，且金刚石均匀分散在Ni-P镀层中。热处理前镀层为非晶结构，经过400 ℃×2 h的热处理后，镀层晶化为硬度更高的Ni3P。金刚石能提高镀层硬度，其中粒径为9 μm的复合镀层硬度最高，达到1261HV。Ni-P金刚石复合镀层的摩擦系数为0.4~0.52，随着金刚石粒径的增大，摩擦系数不断减小。金刚石使镀层的磨损机制发生了变化，随着金刚石粒径的增大，硬质合金球的磨损加剧。结论 随着金刚石粒径的增大，镀层硬度增加，摩擦系数减小，耐磨性增大。

The work aims to study effects of micro-diamond particle size on friction and wear properties of Ni-P diamond electroless composite coatings. An electroless composite coatings containing different sizes of micron diamond particles was prepared by adding different sizes of diamond particles in Ni-P plating solution based upon reasonable Ni-P electroless plating parameters. The effects of diamond particle size on morphology and microstructure of Ni-P diamond electroless composite coatings before and after heat treatment were observed and analyzed by using SEM and XRD. The effects of diamond particle size on the friction and wear properties as well as hardness of the Ni-P and Ni-P diamond composite coatings were investigated by performing hardness as well as friction and wear experiments. Thickness of the prepared coatings was about 30 μm and diamond grits were homogeneously dispersed on the coatings with diamond content of 21%~25%. The Ni-P diamond composite coatings were non crystalline structure before heat treatment, and crystallized into Ni3P of higher hardness after 400 ℃ for 2 h heat treatment. The diamond particles could increase hardness of the Ni-P diamond (9 μm) composite coatings to up to 1261HV. Friction coefficient of the Ni-P diamond composite coatings ranged from 0.4~0.52 and decreased continuously as diamond particle size increased. The addition of diamond particles changed wear mechanism of the Ni-P coating. The cemented tungsten carbide ball was worn more seriously as the diamond particle size increased. Both hardness and wear resistance of Ni- P-Diamond coatings increase while friction coefficient decreases as diamond particle size increases.