目的 通过改变极间距来控制膜层在试样表面的局部生长。方法 通过改变阴极面积来营造均匀与非均匀的电场环境。分别进行微弧氧化试验，根据时间-电压曲线、弧光放电现象、膜层厚度分布等，分析了非均匀电场环境下，极间距对6061 铝合金微弧诱发和生长过程的影响。结果 非均匀场强下，极间距从2 mm 增大到50 mm 时，终止电压先从550 V 降低到450 V，随后又逐渐上升到650 V；微弧诱发时间从10 s 增加到310 s 后，又减小到90 s；中心区域膜层厚度从7.5 μm 减小到1.5 μm，后又增加到4 μm，边缘区域的厚度则从0 μm 缓慢增加到4 μm。微弧氧化在较小极间距的情况下，极间距的增大会降低反应速率和提高膜层的均匀性。结论 极间距的变化会对膜层的生长速率、膜层厚度以及膜层的形貌特征产生很大影响。通过调整合适的极间距可以控制膜层的生长区域，实现膜层的局部优先生长。

The work aims to control local growth of film on sample surface by changing inter-electrode distance. Inhomogeneous electric field was created by changing the cathode area. Micro-arc oxidation tests were conducted respectively. In accordance with time-voltage cruve, arc discharge, distribution of film thickness, etc., effects of inter-electrode distance on micorarc induction and growth process of 6061 aluminum alloy in inhomogeneous field were analyzed. In inhomogeneous field, final voltage firstly decreased to 450 V from 550 V when inter-electrode distance increased from 2 mm to 50 mm, then it gradually increased to 650 V; micro-arc induction time increased from 10 s to 310 s and then decreased to 90 s; film thickness in central area decreased to 1.5 μm from 7.5 μm and then increased to 4 μm while that in marginal area slowly increased to 4 μm from 0 μm. In case of small inter-electrode distance of micro-arc oxidation, increase of inter-electrode distance might reduce reaction rate and improve film homogeneity. Inter-electrode distance can have significant effects on the growth speed, thickness and morphology of the film. Growth region can be controlled by adjusting appropriate inter-electrode distance to realize local preferential growth of the film