Effect of prestrain on the degradation behaviour of aviation organic coatings

The surface morphology of an aviation organic coating during indoor accelerated testing was continually observed by a prestrain method. Environmental scanning electron microscopy and electrochemical impedance spectroscopy were employed for micro-structural characterization and characteristic impedance modulus analysis to systematically study the degradation behavior and failure model of the organic coating under the co-effect of prestrain and tropical marine atmosphere. It is found that the protective properties of the organic coating show a dramatic decrease after tensile prestrain application and go further down during indoor accelerated testing;the degradation of the organic coating is positively correlated with the tensile prestrain level. It is thought that the loss of the protective properties is due to the relatively high stress level which exceeds the breaking strength of the organic coating materials, leading to the formation of microcracks, which serve as routes to the organic coating/alloy interface for solution. But the protective properties of the organic coating exhibit no change after compressive prestrain application and decrease slowly during indoor accelerated testing;the degradation of the organic coating is negatively correlated with the compressive prestrain level.