机场道面除冰液对飞机镀镉层腐蚀机理研究

During the aircraft runs in winter, airlines found that a large number of cadmium plating layer on aircraft parts were corroded because of contacting with the runway deicing/anti-icing fluid. Although the related test methods in existing runway deicing/anti-icing fluid standard can evaluate the affect of runway deicing/anti-icing fluid on aircraft cadmium plating, but the laboratory test methods can not well assess the actual corrosion of runway deicing/anti-icing fluid on aircraft metal materials because the corrosion mechanisms have not been mastered. Preliminary study of our research team found that the corrosion of aircraft cadmium plating due to runway deicing/anti-icing fluid is a complex corrosion process coupling of the electrochemical corrosion, dynamic thin liquid film corrosion and atmospheric corrosion under the repeated wet and dry alternating conditions. In this study, the corrosion behavior and corrosion mechanism of aircraft cadmium plating due to runway deicing/anti-icing fluid will be systematic studied with the proposed corrosion electrochemical methods, especially the advanced electrochemical noise technology and thin liquid film corrosion electrochemical research method, combined with weight loss corrosion tests and various microscopic analytical tools. The research results will help enrich and develop the theory of corrosion electrochemistry, and provide an important theoretical guidance for the establishment of the more realistic corrosion test and assessment standard methods. At the same time, these studies have important theoretical value and practical significance for the R & D of new runway deicing/anti-icing fluid with better corrosion inhibition performance and advanced corrosion control measures of aircraft cadmium plating which will better ensure flight safety.

在飞机冬季运行过程中，航空公司发现大量飞机零部件表面镀镉层的腐蚀与接触跑道除冰液有关，尽管现有的机场道面除冰液标准中有相关测试方法评估除冰液对镀镉层的影响，但由于没有掌握道面除冰液对镀镉层的腐蚀机理，实验室测试方法还不能很好评估实际情况下跑道除冰液对飞机金属材料的腐蚀。项目组前期研究发现，道面除冰液对飞机镀镉层的腐蚀是在干湿交替条件下，电化学腐蚀、动态薄液膜腐蚀以及大气腐蚀等多种条件反复耦合作用下的复杂腐蚀过程。本项目拟采用腐蚀电化学方法，尤其是先进的电化学噪声技术和薄液膜腐蚀电化学研究方法，结合失重腐蚀试验及多种微观分析手段，系统研究道面除冰液对飞机镀镉零部件的腐蚀行为，揭示其腐蚀机理。研究成果有助于丰富和发展腐蚀电化学理论，为建立更符合实际的跑道除冰液对飞机镀镉层腐蚀的测试评估方法提供重要的理论指导，对更好地控制飞机镀镉层腐蚀和开发缓蚀性能更好的道面除冰液具有重要的理论价值和现实意义。

大量使用道面除冰液是机场冬季安全运行的重要工作之一。尽管这些除冰液都通过了现行航空化学品腐蚀测试标准，符合适航要求，但航空公司仍然发现大量飞机零部件表面镀镉层的腐蚀与接触道面除冰液有关。. 本项目对我国北方机场冬季道面除冰液使用情况及航空公司维修基地相关工作进行了系统调研。根据现场调研结果，在实验室模拟除冰液与飞机零部件表面干湿交替和动态薄液膜接触状态，分别建立了低温干湿交替腐蚀试验装置和低温薄液膜腐蚀试验装置及相应试验方法，部分装置及方法已申请专利。采用这些新装置和方法，研究了飞机用镀镉4130钢及基材在两类机场道面除冰液干湿交替作用和薄液膜条件下的腐蚀行为与腐蚀机理，采用不同方法测试了各种条件下镀镉4130钢及基材的腐蚀速率。. 研究发现，4130钢及其镀镉层在机场道面除冰液干湿交替作用和薄液膜条件下主要发生吸氧腐蚀。薄液膜条件对物质（反应物和腐蚀产物）的迁移存在一定的阻碍作用，腐蚀产物迁移困难而在试样表面积累和沉积，形成腐蚀产物膜对材料有一定保护作用；但干湿交替及薄液膜条件极大的促进了试样表面溶解氧扩散过程，进而加速腐蚀过程。在除冰液实际应用过程中经常出现的薄液膜或干湿交替条件下，4130钢及其镀镉层在除冰液中的腐蚀速率明显高于全浸腐蚀条件；在薄液膜一定厚度范围内，腐蚀速率较高。在除冰液作业过程中，随着冰雪不断融化，除冰液将被不断稀释；由于缓蚀剂浓度随之大幅降低，在薄液膜或干湿交替条件下，被稀释的除冰液对4130钢及镀镉层的腐蚀性反而更强，4130钢及镀镉层在低浓度的除冰液中的腐蚀速率明显高于原液或高浓度除冰液。. 研究结果很好地解释了飞机零部件表面镀镉层腐蚀与接触道面除冰液的关系；所建立的薄液膜腐蚀和干湿交替腐蚀试验装置及试验方法，更接近除冰液实际应用条件，对于丰富相关腐蚀理论，建立与实际情况更加吻合的道面除冰液对飞机镀镉层腐蚀的标准测试评估方法具有重要的科学意义、理论指导价值和应用前景。