Abstract When suspensions are stirred at low stirring rates (400–800 rpm), microporous mullite ceramics with high bulk density and low apparent porosity can be achieved because the content of bubbles in suspensions is scarce. With the stirring rate increases from 1200 rpm to 2000 rpm, more and larger bubbles are generated in suspensions. Under actions of the force from spinning blades and the shear stress from adjacent flow layers, these larger bubbles are divided into smaller ones and dispersed evenly, which is helpful to reduce the bulk density and thermal conductivity of as-prepared ceramics. When the stirring rate increases up to 2400 rpm, bubble structures are easily destroyed because some suspensions are thrown out of the mixer by the excessive force of blades, which lead to increases in the bulk density, crushing strength and thermal conductivity.

中文翻译：

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搅拌速率对微孔莫来石陶瓷显微组织和性能的影响

摘要 当悬浮液在低搅拌速率（400-800 rpm）下搅拌时，由于悬浮液中气泡含量少，可以获得高堆积密度和低表观孔隙率的微孔莫来石陶瓷。随着搅拌速度从 1200 转/分增加到 2000 转/分，悬浮液中产生更多更大的气泡。在旋转叶片的力和相邻流动层的剪切应力的作用下，这些较大的气泡被分成较小的气泡并均匀分散，这有助于降低所制备陶瓷的体积密度和热导率。当搅拌速度提高到2400转/分时，由于叶片过大的作用力将一些悬浮液甩出搅拌机，从而导致堆积密度增加，气泡结构很容易被破坏，