铝合金化学氧化膜盐雾试验后腐蚀点评定方法研究

目的制定飞机用2024铝合金表面阿洛丁1200S化学氧化膜盐雾试验后腐蚀点的评定依据。方法通过开展铝合金化学氧化膜盐雾试验,分别利用目视、SEM微观、能谱分析和电化学阻抗测试等手段,表征盐雾试验后的腐蚀形貌及特征。结果试验后样品表面出现的典型腐蚀特征尺寸大于或等于0.15 mm时,正常视力的检测人员均能目视可见。目视可见的黑点、典型彗星状拖尾或只有彗星尾巴等形貌处的化学转化膜和基材已腐蚀,局部有腐蚀点的膜层,其耐蚀性大幅下降,失去对侵蚀性介质的阻挡能力。结论仅出现不符合目视可见和基体腐蚀特征,不能判定为腐蚀点。当出现肉眼可见的黑点,典型彗星状拖尾或只有彗星尾巴等形貌,可判定为腐蚀点。在实际生产检验检测过程中,可采取类似方法研究腐蚀点的评判方法,建立铝合金表面处理盐雾试验后腐蚀图谱和腐蚀点评定准则。

Corrosion Evaluation Method of Aluminum alloy Chemical Oxidation Film after Salt Spray Test

The evaluation basis of corrosion point on surface of 2024 aluminum alloy for aircraft after salt spray test of alodine 1200S chemical oxide film is established.The corrosion morphology and characteristics of aluminum alloy chemical oxide film after salt spray test are characterized by visual, SEM microscopic, energy spectrum analysis and electrochemical impedance test. After the test, when the size of typical corrosion characteristics on the surface of the sample is greater than or equal to 0.15 mm, all the inspectors with normal vision can visually see it. The visible black spots, the typical cometary tail or only the comet tail and other morphologies of the chemical transformation film and substrate have been corroded, and the corrosion resistance of the film layer with local corrosion points has decreased significantly, losing the ability to block the corrosive medium. The corrosion point can not be determined as only the non-compliance with the visible and matrix corrosion characteristics. When black spots are visible to the naked eye, the typical cometary tail or only the comet tail can be judged as corrosion spots. Similar methods can be adopted to study the evaluation method of corrosion spots in the actual production inspection and test, and the corrosion maps and evaluation criteria of corrosion spots after the salt spray test of aluminum alloy surface treatment can be established.