7475铝合金微弧氧化膜在不同载荷下摩擦-磨损行为

Friction-wear Behaviors of MAO Film on 7475 Aluminum Alloy under Different Loads

利用微弧氧化法在7475铝合金表面制备了微弧氧化膜,通过SEM、EDS对氧化膜表面-界面形貌、磨损形貌和化学元素组成进行分析,并用划痕法表征了氧化膜与基体的结合强度。通过摩擦试验考察了试样的磨损性能,测得了其在不同载荷作用下的摩擦系数曲线。结果表明,微弧氧化膜表面存在大量凹凸特征,主要元素为Al、O和Si,另含有其他合金元素和电解质残留元素,氧化膜与基体的结合强度为71.05 N;氧化膜磨损后表面Al含量有所增加,而Si含量呈现下降趋势,此时氧化膜已被磨穿,同时,O含量基本不变,说明磨损后基体表面发生氧化现象;干摩擦条件下氧化膜的摩擦系数为0.8左右,随载荷增大,摩擦系数降低,摩擦曲线稳定性增加;在载荷为10 N时磨损量最大,磨损机制为磨粒磨损和疲劳磨损。

MAO（micro arc oxide） film was prepared on the surface of 7475 aluminum alloy by micro-arc oxidation method, the surface and interface morphologies, wear morphologies and chemical composition were analyzed by SEM and EDS, respectively. The bonding strength of oxide film and substrate was characterized by scratch test. The wear properties of the samples were investigated by friction test, and the friction coefficient curves were measured under different loads. The results show that there are a large number of convex and concave features on the surface of MAO layer, which is mainly composed of Al, O, Si and other alloying elements and electrolyte residual elements, and the bonding strength of the oxide film-substrate is 71.05 N. The content of Al on the surface of MAO film increases in some way after wear while the content of Si decreases, then, the film is worn out, meanwhile, the content of O is basically unchanged, which show that the base metal is oxidized after wear. Under dry friction condition, the friction coefficient of the film is about 0.8, which reduces with the load increasing, and the stability of friction curve increases. The wear quantity is maximum when the loading force is 10 N, and the wear mechanism is abrasive wear and fatigue wear.