外加应变对航空有机涂层防护性能的影响

Effect of Applied Strain on Protective Properties of Aviation Organic Coatings

设计了一种板条形涂层试样预应变施加方法,并通过原始标定和显微观察的方法定量确定有机涂层应变量,以此模拟航空涂层防护体系在服役过程中遭受的应变。将施加了不同应变的板条形有机涂层试样进行户外暴晒,样品所处条件与实际服役中自然环境因素-力学因素耦合作用的情况更为接近,从而可以得到更为准确的防护性能评价结果。结果表明:无外加应变状态的锌黄丙烯酸聚氨酯涂层的阻抗模值随着在万宁自然老化时间的延长而下降,在户外暴晒36个月的过程中,涂层的阻抗模值从1.8×109Ω下降到4.7×105Ω;经过户外暴晒后,外加压应变状态和外加拉应变状态涂层试样的阻抗模值都发生下降,但外加拉应变状态涂层模值降低的幅度更大,表明外加拉应变对有机涂层防护性能影响更大。

A method of pre-strain application on strip coating specimens was introduced. The strain of organic coating was quantitatively measured by microscopy observation of original mark on the coating. Outdoor exposure of the strip organic coating specimens with various strain was carried out, which realized the combination of natural environmental effect and mechanical effect. Therefore, the protective properties of organic coating in real service state can be more precisely evaluated. The re- sult shows that the electrochemical impedance of zinc yellow acrylic polyurethane coating without pre- strain is gradually reduced from 1.8×10^9Ω to 4.7×10^5Ωin 36 months of outdoor exposure in Wan- ning. Electrochemical impedance modulus of coating specimens with either compressive pre-strain or tensile pre-strain decreases after outdoor exposure. However, coating specimens with tensile prestrain exhibit more significant decrease than those with compressive pre-strain in electrochemical impedance, indicating the tensile pre-strain has a great effect on protective properties of organic coatings.