The thermal and mechanical properties of bricks are strongly dependent on both the chemical composition and the microstructural features of the used fired clay material. Focussing on the latter, we here identify, in terms of volume fraction, shape, and orientation characteristics, one-to-several micrometer-sized subdomains (“material phases”) within the SEM-imaged microstructure of two raw clays fired at 880 and 1100 centigrades: (1) quartz grains, (2) muscovite, (3) Fe–Mg mica, (4) feldspar grains, (5) decarbonated dolomite, (6) pores, or (7) binding matrix. This identification rests on the simultaneous use of Scanning Electron Microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDX), with correspondingly obtained data entering statistical analyses based on the Otsu algorithm, and complemented by minimum grain size and grain shape requirements, as well as by logical exclusion criteria. Crystalline and amorphous phase shares were additionally confirmed by X-ray powder diffraction measurements (PXRD). As for the investigated clays, an increased firing temperature results in dehydroxylation of muscovite, and in a reduced appearance of feldspar grains.

中文翻译：

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基于 EDX/XRD 的烧制粘土扫描电子显微照片中微米尺寸域的识别

砖的热性能和机械性能在很大程度上取决于所用烧制粘土材料的化学成分和微观结构特征。着眼于后者，我们在这里根据体积分数、形状和取向特征，确定了在 880 度和 880 度烧制的两种原始粘土的 SEM 成像微观结构中的一到几个微米大小的子域（“材料相”）。 1100 摄氏度：(1) 石英颗粒，(2) 白云母，(3) Fe-Mg 云母，(4) 长石颗粒，(5) 脱碳白云石，(6) 孔隙，或 (7) 粘合基质。这种识别依赖于同时使用扫描电子显微镜 (SEM) 和能量色散 X 射线光谱 (EDX)，相应地获得的数据进入基于 Otsu 算法的统计分析，并辅以最小晶粒尺寸和晶粒形状要求，以及符合逻辑的排除标准。通过 X 射线粉末衍射测量 (PXRD) 进一步证实了结晶和非晶相份额。至于所研究的粘土，提高烧成温度会导致白云母脱羟基，并减少长石颗粒的出现。