飞机表面超疏水材料在低温高湿环境中憎水性能失效机理及性能改进研究

Icing on airfoil will cause great danger on aircraft flight and safety performance. It is great of importance to develop an effective anti-icing technique to prevent flight accidents caused by icing. Superhydrophobic surface is a class of material with low surface energy and special physical and chemical properties. By the well design of the surface structure and surface chemistry the freezing time of supercooled water on it will be greatly extended and the adhesion force between ice and substrate will be significantly reduced. Thus, there is enough time for supercooled water to detach from icing surface by external force before it is solidified. However, the failure of hydrophobicity of superhydrophobic surface at low temperature and high humidity environment prevent its application in modern aircraft. In this project the failure mechanism of superhydrophobic surface at low temperature and high humidity environment is thoroughly studied. The relationships between surface wettability and icephobicity and surface chemistry and surface structure are fully investigated and the effects of icing and de-icing cycle on surface chemistry, surface structure and surface wettability are also studied. The hydrophobic properties of current superhydrophobic surface at low temperature and high humility conditions, especially in the icing rain or frost conditions, will be greatly improved through optimized design of surface chemistry and surface structure. After completion of this project the key technical barrier for superhydrophobic surface application in civil aircraft will be solved and strong technical support will be provided for superhydrophobic surface application in civil aircraft.

飞机表面结冰对飞机飞行性能及安全性将造成极大危害，大力发展有效防除冰技术对预防因结冰造成的飞行事故具有重大意义。飞机表面超疏水材料是一类具有低表面能及特殊物理化学性能的材料，通过对固体表面结构及表面化学的设计有效延长了过冷水在飞机表面的结冰时间，降低了冰与基材间的附着力，使过冷水在凝固前有足够的时间依靠外力作用脱离结冰表面。针对当前超疏水表面在低温高湿环境中疏水性能失效的问题，本项目拟对超疏水表面在低温高湿环境中憎水性能失效机理进行研究，考察表面化学及表面微观结构与材料表面润湿性及防覆冰性的关系，探讨除结冰循环对材料表面化学、表面结构及润湿行为的影响，通过对超疏水涂层表面化学及表面微纳结构的优化设计，提出增强超疏水表面在低温高湿环境中，尤其是在冻雨、成霜等极端条件下憎水能力的设计方案，解决制约其在民航客机应用的关键技术问题，为防疏冰涂层材料在航空领域的应用提供有力技术支持。

针对当前超疏水表面应用中出现的问题，项目首先对超疏水表面在低温高湿环境中憎水性能失效机理进行了研究，考察了固体表面润湿性、超疏水性及防冰性之间的关系。为研究表面多级微纳结构设计与表面润湿性及表面防覆冰的关系，项目组以硅氧烷为疏水剂，采用浸渍法在具有开放及封闭微结构的金属铝板上制备了超疏水表面。结果表明，超疏水表面静态接触角随结除冰次数的增加而减少，滚动角随结除冰次数的增加而增大，且在多个结冰除冰循环后，表面开放微结构的金属铝板丧失其超疏水性，表面封闭微结构的金属铝板仍保持其超疏水性。为考察表面化学性质与表面润湿性及表面防覆冰能力的关系，项目组以金属铝合金为基底，分别以氯化铜、氢氧化钠及盐酸为刻蚀液，利用十七氟葵基三乙氧基硅烷为疏水剂，制备了不同疏水性能的表面。结果表明，在中低温环境中，使用氯化铜或低浓度氢氧化钠对铝合金表面进行刻蚀，其后将其浸渍在含低表面能的有机溶剂中即能制备出具有超疏水性的表面，且表面具有微纳米二级疏水结构。表面疏水性能随刻蚀液浓度的增加而增强,表面接触角随刻蚀时间及刻蚀温度的增加而增大。通过上述研究，项目组提出了提出实现在经过多次结冰除冰循环后，仍然能够将接触角保持在150°以上，具有超高的疏水性以及保持能力，同时，还能够将水滴在表面结冰的时间延长保持在190s以上，将冰块在表面的剪切强度保持在210kPa以下，具有良好的防冰、疏冰效果的表面涂层配方组成方案。