Five microporous mullite-corundum refractory aggregates were prepared from Al(OH)₃ and kaolinite gangue through in situ decomposition synthesis technique. The effects of the sintering temperature (1400–1600°C) and the particle sizes of raw materials (20.6–94.5 μm) on the microstructures and strengths of the aggregates were investigated through X-ray diffractometer, scanning electron microscopy, and energy-dispersive spectrometer etc., to find out the technological conditions to be controlled in industrial production. The higher sintering temperature promoted the reaction between Al(OH)₃ and kaolinite gangue, leading to the development of primary-mullite as well as the generation of secondary-mullite, which promoted the formation of the neck and improved the strength. Meanwhile, the dense mullite layers were formed continuously on the surface of Al(OH)₃ pseudomorphs, making the micropores inside the pseudomorphs become closed pores, which increased the closed porosity of the aggregates. The reduction of the particle sizes of raw materials changed the particle packing behavior, accelerated the rearrangement of the Al(OH)₃ pseudomorph particles during the process of reactive sintering, and then reduced the closed porosity. To realize the industrial production of microporous mullite-corundum refractory aggregate with high strength (103 MPa) and high closed porosity (16.1%), the sintering temperature should be at about 1600°C, and the median diameter of raw materials should be at 94.5 μm.

中文翻译：

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轻质耐火材料用微孔莫来石-刚玉骨料的组织与性能

_{以Al(OH) 3}和高岭石脉石为原料，采用原位分解合成技术制备了五种微孔莫来石-刚玉耐火骨料。通过X射线衍射仪、扫描电镜和能量色散仪研究了烧结温度（1400~1600℃）和原料粒径（20.6~94.5 μm）对骨料微观结构和强度的影响。光谱仪等，找出工业生产中需要控制的工艺条件。较高的烧结温度促进了Al(OH) _{3之间的反应}和高岭石脉石，导致初生莫来石的发育和次生莫来石的生成，促进了颈部的形成，提高了强度。_{同时，Al(OH) 3}假晶表面连续形成致密的莫来石层，使假晶内部的微孔变成闭孔，增加了聚集体的闭孔率。原料粒径的减小改变了颗粒堆积行为，加速了Al(OH) _3的重排反应烧结过程中的假晶颗粒，进而降低了闭合孔隙率。实现高强度（103 MPa）、高闭孔率（16.1%）微孔莫来石-刚玉耐火骨料的工业化生产，烧结温度应在1600℃左右，原料中径应在94.5微米。