目的 强化Ni基镀层并确定Al2O3尺寸对复合镀层性能的影响。方法 在以硬度为评价标准的最佳工艺条件下，制备了三种尺寸的Al2O3（微米级、50 nm、30 nm）复合镀层，研究分析了不同尺寸Al2O3复合镀层的表面形貌、显微硬度、耐磨、耐蚀等性能。结果 纳米复合镀层的表面形貌比微米复合镀层更光滑、平整、致密，晶粒更细小。Al2O3微粒尺寸越小，镀层越致密。纳米复合镀层的显微硬度、耐磨性能、耐蚀性能、抗高温氧化等性能均优于微米复合镀层及纯Ni镀层。热处理后的纳米复合镀层表面更加平整致密，热处理能显著提高镀层的显微硬度。50 nm复合镀层在保温温度为400 ℃时达显微硬度最大值461HV，30 nm复合镀层在保温温度为500 ℃时达显微硬度最大值496HV。热处理对纳米复合镀层的耐磨性能改善不明显。结论 Al2O3的尺寸越小，复合镀层的性能越好。

The work aims to strengthen the Ni-based plating and determine the effects of Al2O3 size on properties of the composite plating. Al2O3 composite platings in three sizes (micron, 50 nm and 30 nm) were prepared under optimum processing conditions taking hardness as evaluation criteria. Surface morphology, microhardness, wear resistance and corrosion resistance of the Al2O3 composite platings in three sizes were studied and analyzed. Surface morphology of the nanocomposite coating was smoother, denser and finer than that of the micron composite plating. The smaller the nanoparticles were, the denser the plating was. Microhardness, wear resistance, corrosion resistance and high temperature oxidation resistance of the nanocomposite plating were better than those of the micron composite plating and pure Ni plating. The surface of the nanocomposite plating was smoother and denser after heat treatment. The microhardness of the plating could be remarkably improved by heat treatment. The 50 nm and 30 nm composite plating exhibited the maximum microhardness of 461HV and 496HV at 400 ℃ and 500 ℃, respectively. Wear resistance of the nanocomposite plating was not obviously improved by heat treatment. The smaller the Al2O3 particles are, the better the performance of composite platings will be.