The effect of the spark plasma sintering (SPS) process on mullite formation in porcelains was studied using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. SPS affected the kinetics and morphology of formed mullite. After sintering at 1100°C, unlike conventional sintering, SPS promoted the formation of mullite due to the combination of vacuum and applied pressure. Mullite crystal growth was altered by the atmosphere (vacuum), dwell time (0-15 mins), and temperature (1000-1200°C). The applied pressure caused the mullite needles to orient perpendicular to the direction of the applied load. Depending on SPS dwell time, the mullite formed after sintering at 1100°C also had different crystal structure (tetragonal for short dwell time of 0-5min and orthorhombic for a long dwell time of 10-15min). Dissolution of mullite was observed at 1100°C by extending the dwell time by up to 15 minutes and the dissolved mullite re-precipitated on the small needles (~40nm) via Oswald ripening resulting in larger mullite needles (~60nm). This article is protected by copyright. All rights reserved.

中文翻译：

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放电等离子烧结 (SPS) 对瓷器中莫来石形成的影响

使用 X 射线衍射、扫描电子显微镜和透射电子显微镜研究了放电等离子烧结 (SPS) 工艺对瓷器中莫来石形成的影响。SPS 影响形成的莫来石的动力学和形态。在 1100°C 烧结后，与传统烧结不同，SPS 由于真空和施加压力的结合促进了莫来石的形成。莫来石晶体的生长受气氛（真空）、停留时间（0-15 分钟）和温度（1000-1200°C）的影响。施加的压力导致莫来石针垂直于施加载荷的方向定向。根据 SPS 停留时间的不同，在 1100°C 下烧结后形成的莫来石也具有不同的晶体结构（四方晶系停留时间短为 0-5 分钟，正交晶系停留时间为 10-15 分钟）。通过将停留时间延长至 15 分钟，观察到莫来石在 1100°C 的溶解，溶解的莫来石通过奥斯瓦尔德熟化重新沉淀在小针（~40nm）上，导致更大的莫来石针（~60nm）。本文受版权保护。版权所有。