Mechanical degradation occurs in fuel cell membranes due to the dynamic environmental conditions of operational duty cycles, and is regarded as a critical determinant of fuel cell durability and lifetime. Imaging-based failure analysis is typically employed to characterize structural and morphological aspects of the degradation, and 3D visualization capability of X-ray computed tomography is effectively expanding the scope of this analysis. This work further leverages the additional non-destructive and non-invasive attributes of this visualization technique to capture 4D information pertaining to the evolution of mechanical degradation in fuel cell membranes. A custom fuel cell fixture is utilized to periodically track identical membrane locations during the course of its mechanical degradation, which is generated through an accelerated stress test. The predominant fatigue-driven membrane crack development process is found to proceed non-linearly in time and is spatially concentrated under the uncompressed channel regions. Membrane cracking location is shown to be strongly correlated with beginning-of-life MEA defects, namely, electrode cracks and delamination. In situ crack propagation rates are quantified and the presence of a ‘crack closure’ effect during mechanical membrane degradation is demonstrated. Unlike crack initiation, crack propagation in the membranes does not appear to be significantly influenced by electrode morphology.

由于工作占空比的动态环境条件，在燃料电池膜中会发生机械降解，这被认为是决定燃料电池耐用性和寿命的关键因素。通常使用基于成像的故障分析来表征退化的结构和形态方面，X射线计算机断层扫描的3D可视化功能有效地扩展了这种分析的范围。这项工作进一步利用了这种可视化技术的其他非破坏性和非侵入性属性，以捕获与燃料电池膜中机械降解演变有关的4D信息。定制的燃料电池固定装置用于在机械降解过程中定期跟踪相同的膜位置，这是通过加速压力测试生成的。发现主要的疲劳驱动膜裂纹发展过程在时间上是非线性的，并且在空间上集中在未压缩的通道区域下。膜的开裂位置与寿命开始的MEA缺陷（即电极开裂和分层）密切相关。量化了现场裂纹扩展速率，并证明了机械膜降解过程中“裂纹闭合”效应的存在。与裂纹萌生不同，膜中的裂纹扩展似乎不受电极形态的显着影响。