力学-老化/腐蚀耦合作用下有机涂层/金属体系失效机理及损伤模型研究

Aeronautical organic coating is widely used as a means of corrosion protection for aircraft. However, the protective effect of coating becomes more obvious under the conditions of mechanical and environmental factors superimposed, and it often becomes a weak link of the whole protection system. At present, some qualitative conclusions about the failure mechanism of organic coatings under service conditions have been obtained. However, the coupling mechanism between mechanical and environmental factors has not yet been defined, and the damage model of coating/metal system under coupling action is lacking. In this project, based on the silicone-epoxy coating/2024 Al-alloy system and its mechanics-aging/corrosion coupling environment, focused on the corrosion damage characteristics of the coating/metal system, the effect of mechanical factors on microcosmic evolution of aging/corrosion and electrochemical behavior of the organic coating system is studied, revealing the transmission rule of eroded particles, aging failure of organic coatings and the mechanism of corrosion failure at the interface of the system. The coupling mechanism between mechanics and environmental factors is clarified. On the basis of this, the damage model of mechanical and environmental factors coupling for the coating/Al-alloy system is established. The results not only enrich the theory of coating protection and corrosion damage in service environment, but also provide theoretical support and technical guidance for the development of new aviation coatings and evaluation of environmental adaptability of coatings.

航空有机涂层是飞机广泛采用的一种腐蚀防护手段，而涂层的防护性在力学与环境因素叠加的服役条件下失效过程变得更明显，往往成为整个防护体系的薄弱环节。目前针对服役条件下有机涂层失效机理的研究获得了一些定性结论，但尚未明确力学与环境因素的耦合作用机制，缺少耦合作用下的涂层/金属体系损伤模型。本项目针对有机涂层/铝合金体系及其力学-老化/腐蚀耦合环境，围绕涂层体系的老化/腐蚀损伤特点，研究力学因素对有机涂层体系老化/腐蚀细微观演化及电化学行为的影响规律，揭示侵蚀粒子传输规律、有机涂层老化失效及体系界面处腐蚀失效机理，明晰力学与环境因素耦合作用机制，建立力学-老化/腐蚀耦合作用下的损伤模型。研究成果不但能丰富服役条件下的涂层老化及基体腐蚀损伤理论，还为发展新型航空涂层以及评价涂层的环境适应性提供理论支持和技术指导。

航空有机涂层的防护性能在实际服役过程中不仅受到腐蚀环境因素而且还受到载荷（应力或应变）因素的影响。本项目针对有机硅环氧涂层/2024铝合金体系及其载荷/腐蚀耦合环境，围绕涂层/金属体系的腐蚀损伤特点，研究力学-老化/腐蚀耦合作用下涂层/金属体系不同腐蚀阶段的电化学行为及损伤机制，研究载荷作用对涂层中水传输行为的影响，揭示载荷/环境耦合作用下涂层/金属体系的损伤失效机理。主要结论如下：.（1）采用电化学测试、FTIR-ATR及附着力试验等方法研究了不同压载荷对涂层/金属体系的腐蚀失效机理的影响。研究表明在受压载荷作用下，能减小金属的腐蚀倾向和腐蚀速率，有助于涂层防护性能的改善；能一定程度上消除涂层孔洞，有效的抵挡了水和腐蚀介质的渗透，减小了涂层的吸水率，抑制了金属基体的腐蚀速率和剥离面积的增大，提高其耐蚀性，延缓涂层/金属体系的腐蚀失效过程。.（2）采用电化学测试、FTIR-ATR及附着力试验等方法研究了不同拉载荷对涂层/金属体系的腐蚀失效机理的影响。研究表明在受拉载荷作用下，能加快金属的腐蚀反应速率，使涂层的防护性能明显下降；受拉载荷通过改变涂层微观结构加快水和腐蚀介质的渗透速度，使金属基体的腐蚀速率和剥离面积增大，对腐蚀电化学行为起促进作用，加快涂层/金属体系的腐蚀损伤过程。.（3）结合热力学、腐蚀动力学及力学-化学效应理论揭示涂层/金属体系在载荷/环境耦合作用下的腐蚀损伤机制，研究表明引入载荷因素能提高金属电极的电化学活度和腐蚀速率，加剧腐蚀反应的生成。金属在弹性载荷范围内，其阳极电位负移了V△P/zF，电极腐蚀电流速率是无载荷作用下的exp(V△P/RT)倍。.研究成果不仅能丰富服役环境下的涂层防护及腐蚀损伤理论，还为发展新型航空涂层以及评价涂层的环境适应性提供理论支持和技术指导。