The oxidation behavior of matrix‐grade graphite in air‐ or steam‐ingress accident scenarios is of great interest for high‐temperature gas reactors (HTGRs). In this study, the microstructures of two variants of matrix‐grade graphite based on the German A3‐3 and A3‐27 formulations were characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy, and correlated to oxidation behavior observed through thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Through TEM imaging and selected area electron diffraction (SAED), a higher volume fraction of partially graphitized carbon was identified in the A3‐3 type graphite than in the A3‐27 type. This structure is believed to have contributed to the accelerated oxidation exhibited by A3‐3 in the chemical reaction‐controlled oxidation regime.

中文翻译：

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微观结构对A3基体级石墨氧化行为的影响

高温气体反应堆（HTGR）对空气或蒸汽入口事故中基体级石墨的氧化行为非常感兴趣。在这项研究中，基于德国A3-3和A3-27配方的两种基体级石墨变体的微观结构用扫描电子显微镜（SEM），透射电子显微镜（TEM）和拉曼光谱进行了表征，并与通过热重分析（TGA）和差示扫描量热法（DSC）观察到的氧化行为。通过TEM成像和选择区域电子衍射（SAED），发现A3-3型石墨中部分石墨化碳的体积分数高于A3-27型石墨。