直升机蒙皮典型结构有机涂层防护性能在模拟高原大气环境中的变化

Degradation of Protective Properties of Organic Coatings on Typical Helicopter Skin Structure in Simulated Plateau Atmospheric Environment

目的评价服役于高原大气环境中的直升机蒙皮典型结构及其防护体系的防护性能。方法通过模拟高原大气环境加速试验方法再现直升机蒙皮典型结构防护体系实际服役过程中出现的损伤,利用扫描电镜对表面微观形貌进行观察,采用电化学阻抗谱测试研究有机涂层阻抗的变化。结果在实验室加速试验中,蒙皮试验件螺钉周边先出现局部腐蚀,之后腐蚀产物又逐渐减少,而铆钉周边经过多个周期后腐蚀产物都没有显著增多。螺钉中间区域有机涂层电化学阻抗模值直至第8个周期后与原始情况相比才大幅度下降,而铆钉中间区域有机涂层电化学阻抗模值在试验中多次明显下降。结论铆钉周边的有机涂层经过多个周期加速试验仍具有阻挡腐蚀性介质的作用。与螺钉结构的情况相比,铆钉中间区域有机涂层防护性能退化显著。

Objective To evaluate protective properties of typical helicopter skin structure and its protection system that serves in plateau atmospheric environment. Methods The damage in the protective system of typical helicopter skin structures in service was reproduced via accelerated testing method for simulation of plateau atmospheric environment. Scanning electron microscopy was employed to observe the surface micro morphology. Electrochemical impedance measurement was used to study the degradation of impedance of organic coatings. Results During laboratory accelerated testing, localized corrosion pre- ferentially initiated at the periphery of bolts in the skin specimen but then the corrosion product gradually disappeared. In the periphery of rivets, corrosion product did not accumulate significantly after a number of cycles. The electrochemical impedance modulus of the organic coatings in the central area between bolts decreased remarkably after 8 cycles. The electrochemical impedance modulus of the organic coatings in the central area between rivets repeatedly shows obvious decrease during testing.Conclusion Organic coating around rivets shows the capability to block corrosive media after a several cycles of accelerated testing. Compared with the situation on bolt structure, the organic coating in the central area between rivets exhibits distinct degradation in protective properties.