典型飞机管状结构内腔阴极电泳防腐技术

目的以典型直升机主减撑杆为例,优选小内径管状结构内腔阴极电泳防腐工艺。方法应用中性盐雾试验、丝状腐蚀试验、电化学阻抗法等方法,考察不同电泳电压和槽液温度对电泳漆膜防腐蚀性能的影响;采用加速腐蚀试验对比分析防腐措施改进前后涂层的防腐蚀效果。结果 4种电泳漆膜中性盐雾试验480 h后划痕处均出现锈蚀,盐雾试验2000 h后,4~#工艺电泳电压350V、槽液温度34.9℃时,制备的电泳漆膜划痕处锈蚀未见明显变化。4种电泳漆膜耐丝状腐蚀性能满足MIL-PRF-23377J的要求。在3.5%(质量分数)Na Cl溶液中浸泡2000 h后,4~#工艺制备的漆膜电化学阻抗值最大,稳定在6×1010Ω·cm~2左右;3~#工艺电泳电压350 V、槽液温度34.3℃时,制备的漆膜电化学阻抗值最小,从浸泡初期的6×10~(10)Ω·cm~2降至9×10~7Ω·cm~2。各项性能测试表明,4种电泳工艺制备的漆膜均具有优异的防腐性能;4~#工艺制备的漆膜防腐性能最优,4种电泳工艺中最佳管状结构内腔电泳工艺为:电泳电压350 V,槽液温度34.9℃。阴极电泳涂装替代灌涂后,涂层的使用寿命可提高40倍以上。结论阴极电泳防腐技术能够有效解决内腔结构防腐难题,明显改善内腔结构的抗腐蚀品质。

Cathodic Electrodeposition Technique for Anticorrosion Improvement on Tube Inner Structure of Typical Aircraft

Objective Cathodic electrodeposition technique was employed for improving the corrosion resistance of typical tube inner structure. Methods Electrochemical impedance spectroscopy ( EIS) was coupled with salt spray test and filiform corrosion method to investigate the effects of applied voltage and bath temperature on the corrosion resistance of the coatings. Using acceler-ated corrosion test methods, the corrosion resistance of the coatings after the improvment of anticorrosion was evaluated. ResultsAll the electrophoresis paint films showed rust in the scratch when the neutral salt spray test was conducted for 480 h. The test re-sult showed only for 4# coating (applied voltage 350 V and bath temperature 34. 9 ℃), no rust expanded in the scratch of the test sample after salt spray test for 2000 h. The filiform corrosion resistance of all the electrophoresis paint films could meet the require-ment of MIL-PRF-23377J. After immersion in 3. 5% NaCl aqueous solution for 2000 h, 4# coating possessed the maximum imped-ance value of 6×1010Ω·cm2, while 3# coating (applied voltage 350 V and bath temperature 34. 3℃) possessed the minimum im-pedance value and the impedance value changed from 6×1010Ω·cm2 at the early stage of immersion to 9×107Ω·cm2. It indica-ted that all the films produced by the four electrocoating processes showed good corrosion resistance, while 4# coating possessed the best corrosion resistance. The results showed that the optimal process parameters of tube inner structure were applied voltage 350 V and bath temperature 34. 9 ℃. The life period of the coating could be increased by over 40 times if irrigation film was replaced by electrophoresis paint film. Conclusion The corrosion problem of typical tube inner structure could be solved by cathodic electro-deposition technique which improved the anticorrosion performance of the holllowed structure.