Al-Cu-Li合金在盐溶液中的腐蚀行为以及腐蚀机理研究进展

Research Progress on Corrosion Behavior and Corrosion Mechanism of Al-Cu-Li Alloy in Sodium Chloride Solution

摘要:

Al-Cu-Li合金是航天航空工业中重要的轻质结构材料，已成为国产大飞机结构件的关键材料之一。飞行器在海洋等潮湿环境服役时，易受到具有腐蚀性的卤化物阴离子的侵蚀，尤其是在Cl^-离子侵蚀作用下，Al-Cu-Li合金构件表面易出现点蚀、晶间腐蚀和剥落腐蚀现象。Al-Cu-Li合金的局部腐蚀主要归因于合金相与合金基体间存在电势差，进而导致在腐蚀介质中形成微型腐蚀原电池。综述了Al-Cu-Li合金在NaCl溶液中的腐蚀行为以及热处理工艺对合金耐腐蚀性能的影响，重点分析了粗大第二相颗粒和时效析出相对Al-Cu-Li合金腐蚀性能的影响，研究了典型第3代Al-Cu-Li（2A97-T3、2A97-T6、2060-T8和2099-T83）合金以及航空用常规高强铝合金2024-T4在3种不同浓度NaCl溶液中的侵蚀行为以及在质量分数3.5%NaCl溶液中的电化学行为。综合分析各试样的微观腐蚀形貌、腐蚀电化学参数以及腐蚀程度，最终得出各试样的耐腐蚀性能由强至弱为：2A97-T3>2A97-T6>2024-T4>2060-T8>2099-T83。最后揭示了Al-Cu-Li合金在腐蚀介质中的腐蚀机理，总结了在海洋环境下铝合金的防腐措施。本文为后续Al-Cu-Li合金防腐性能的发展和飞机耐腐蚀性能的提升提供了参考。

Abstract:

Al-Cu-Li alloy is a critical lightweight structural material in aviation and aerospace industry, which has become one of the key materials to manufacture the large aircraft structures in China. When the aircraft is in service in humid environments such as the ocean, it is vulnerable to be eroded by corrosive halide anions, and especially under the Cl^- ion erosion, its surface of Al-Cu-Li alloy components is prone to pitting corrosion, intergranular corrosion and exfoliation corrosion. The local corrosion of Al-Cu-Li alloy is mainly attributed to the potential difference between the alloy phase and the alloy matrix, which leads to the formation of micro-corrosion battery in the corrosive medium. The corrosion behavior of Al-Cu-Li alloy in NaCl solution and the effect of heat treatment on the corrosion resistance of the alloy were reviewed. The effects of coarse second phase particles and aging precipitates on the corrosion properties of Al-Cu-Li alloy were analyzed. In addition, the corrosion behavior in NaCl solution of different contents and electrochemical behavior in 3.5wt% NaCl solution of typical third generation Al-Cu-Li (2A97-T3, 2A97-T6, 2060-T8 and 2099-T83) alloys and conventional high strength aluminum alloy 2024-T4 used in aviation were studied in NaCl solution. The micro-corrosion morphology, corrosion electrochemical parameters and corrosion degree of each sample were analyzed. Finally, the corrosion resistance of each sample was obtained, from strong to weak in an order of: 2A97-T3>2A97-T6>2024-T4>2060-T8>2099-T83. Finally, the corrosion mechanism of Al-Cu-Li alloy in a corrosive medium was revealed, and the anti-corrosion measures of aluminum alloys in marine environments were summarized. This reseach progress provides reference for the subsequent development of the Al-Cu-Li alloy corrosion protection process and the enhancement in the corrosion resistance of aircraft in humid environments.