质子交换膜燃料电池密封材料的环境失效机制与寿命评价方法研究

Abstract:The chemical and mechanical durability and stability of elastic gasket seals in proton exchange membrane fuel cell operating conditions which is high temperature, acidic and exists a compressive load, is important to the electrochemical property and safety of fuel cell. With the help of modern material advanced analysis techniques the aging process of the elastomer is analyzed under the synergistic effect of temperature-load-chemistry multiple factors in PEM fuel cell environment. It is attempted to reveal the degradation mechanism from microscopic molecular structure. Then, the change law of mechanical properties is studied by mechanical tests and the damage constitutive model is hoping to be established. Finally, based on Time-Temperature Superposition Principle, Arrhenius method and mechanical test data, the life assessment method of elastic materials exposed to fuel cell environment is established. In this interdisciplinary program the mechanical, chemical and material analyses were included. Through the accomplishment of this project, the basic rule of environmental failure of the gasket materials used in fuel cell through the view point of chemo-mechanical analysis can be found and the life assessment method which can be used for engineering application can be developed. Also, the results can provide a scientific guidance and theoretical foundation for high reliability and safety of fuel cell and for low cost and long-term durability gasket materials.

摘要：密封垫片在质子交换膜燃料电池高温、受压、偏酸性环境中的化学与机械性能的持久性与稳定性是影响燃料电池电化学性能与安全运行的重要问题。以弹性体密封材料为研究对象，借助现代材料先进分析技术对材料在燃料电池环境中温度-载荷-化学多因素协同作用下的材料老化过程进行分析研究，从微观分子结构揭示其损伤机理；其次，通过老化试样的机械性能试验，探讨材料老化过程中机械性能变化规律并建立材料粘弹性力学损伤模型；最后，基于时间-温度叠加原理及Arrhenius方程和机械性能变化规律，建立材料在燃料电池环境中温度-载荷-化学多因素协同作用下的寿命评价方法。本项目体现了力学、化学、材料学等多学科领域的交叉，有望从化学-力学角度阐述燃料电池环境下密封材料环境失效机制并建立评估方法，为提高燃料电池的可靠性、安全性提供科学指导，并为开发低费用、持久性密封材料提供理论依据。

本项目以实现弹性体垫片在燃料电池环境中温度、载荷、化学介质协同作用下，其损伤机理研究与寿命预测为目标。首先，探讨了材料在温度、载荷、化学介质协同作用下损伤试验及加速试验方法的建立，深入研究了其化学结构在相应试验条件下演变情况，揭示其损伤机理，并确定损伤机理相同时最优加速试验条件。其次，利用万能材料试验机及压缩永久变形仪器，对材料在受压状态下力学性能的衰减趋势进行研究，掌握其在特定压缩变形量情况下，压缩载荷随时间衰减规律。为研究材料寿命预测方法奠定基础。最后，基于Arrhenius方法，时间-温度叠加原理，通过构建主曲线，外推得到在垫片材料长期处于压缩应力的工况下，其预紧力衰减至特定值时时间，初步得到材料在PEM燃料电池操作环境下的使用寿命预测方法。建立三级数Maxwell本构模型很好表达弹性体材料力学性能变化规律。