目的 通过调节负电压参数，制备具有较高硬度与较好耐磨性的2A50铝合金微弧氧化陶瓷层。 方法 通过微弧氧化，利用双极性脉冲电源，在硅酸盐为主的电解液中，于2A50铝合金表面原位生成耐磨的高硬度陶瓷层。通过改变负电压，研究其对微弧氧化陶瓷层相组成、微观结构、显微硬度和摩擦磨损性能的影响规律。利用扫描电子显微镜、X射线衍射仪表征微弧氧化膜层的微观形貌、物相组成。利用显微硬度计测试微弧氧化膜层的硬度，并通过摩擦磨损试验机评价膜层的耐磨性。结果 涂层的主要相组成为γ-Al2O3。陶瓷层由内侧致密层和外部疏松层组成，随着负电压的提高，微孔的数量和尺寸先减少后增大。微弧氧化后，2A50铝合金得到明显强化，经–100 V负电压的微弧氧化，其显微硬度由未处理的75HV0.5提高至1321HV0.5。微弧氧化陶瓷层具有良好的耐磨性，摩擦系数在0.35~0.55之间，其磨损机制为磨粒磨损和粘着磨损共存。结论 正电压较高时，较低负电压可很好地抑制微弧氧化过程中的强放电现象，以获得较为致密、坚硬且耐磨的膜层。

The work aims to prepare 2A50 aluminum alloy micro-arc oxidation ceramic layer with higher hardness and better wear resistance by adjusting the negative voltage parameters. With a bipolar pulse power, wear-resistant ceramic coatings with high micro-hardness were fabricated in-situ on 2A50 aluminum alloy by micro-arc oxidation method in silicate electrolyte. The effect of negative voltage on microstructure, phase structure, micro-hardness and wear properties was investigated by changing the negative voltage from 0 to –200 V. The microstructure, phase structure, micro-hardness and wear properties were characterize, measured and evaluated by SEM, XRD, Vikor hardness tester and tribology tester. The phase of the obtained coatings was mainly composed of γ-Al2O3. The coating consisted of the inner dense layer and the outer loose layer. As the negative voltage increased, the quantity and size of the pin holes in the coatings first decreased and then increased. Micro-arc oxidation could greatly strengthen 2A50 aluminum alloy and the micro-hardness increased from 75HV0.5 to 1321HV0.5 after a micro-arc oxidation under a negative voltage of –100 V. The obtained ceramic coatings exhibited good wear resistance and the friction coefficient was in the range of 0.35~0.55. The wear mechanism was deduced to be the combination of abrasive wear and adhesive wear. When the positive voltage is high, the lower negative voltage can well suppress the strong discharge phenomenon in the micro-arc oxidation process to obtain a dense, hard and wear-resistant film layer.