铝合金棱角部位阳极氧化膜形貌分析

对铝合金进行阳极氧化，并进行化学浸泡试验和点滴试验，用电子探针观察棱角部位氧化膜的形貌。结果表明，试样表面部位氧化膜化学浸泡试验180min无氢气泡逸出，点滴试验时间大于30min没有观察到腐蚀迹象，达到了航空工业部标准（HB5055-1993），耐蚀性能优异。然而，试样的棱、外角和内角观察到氢气泡逸出，该处氧化膜产生破损，导致基体金属遭受腐蚀。电子探针分析发现，铝合金棱角部位氧化膜产生裂纹。其原因是棱角部位氧化膜存在边缘效应，阻止了氧化膜在三维方向连续生长，与表面部位相比，棱角部位氧化膜变薄，导致基体金属棱角部位优先遭受腐蚀。

Morphology Analysis of Anodic Oxide Film of Aluminum Alloy at Edges and Corners

An anodizing technology was used in anodic oxidation of aluminum alloy, chemical immersion test and drop test were used to test corrosion resistance of the oxide film, and electron probe was used to analyze the oxide film morphology at edges and corners. The results showed that hydrogen bubbles didn't appear in the 180 min chemical immersion test, and there were no corrosion phenomena on the oxide film during the liquid drop test more than 30 min, which reached the standard of Aviation Industry Ministry (HB 5055-1993). The corrosion resistance of the oxide film was excellent. However, hydrogen bubbles appeared at edges, external angles and internal angles of the sample. the oxide film was broken at those locations, which led to matrix metal corrosion. Electron probe results indicated that cracks were found at edges and corners of aluminum alloy's oxide film. The reason was that edge effect prevented oxide film of edges and corners from continuous growing in three-dimension directions. The oxide film at edges and corners was thinner than that on the surface, which led to the edges and corners corroded first.