Functional refractory materials for flow control devices of molten steel in continuous casting used to be prepared from Al₂O₃–C refractories containing dense corundum aggregates. According to the traditional concept, the denser the refractories, the higher the strength of refractories. However, we prepared a new lightweight Al₂O₃–C refractory material using microporous corundum aggregates instead of dense corundum aggregates, which were reinforced by in situ formed SiC whiskers. A comparative analysis of microstructures and properties was carried out for conventional and lightweight Al₂O₃–C refractories with and without Si powder addition. We showed that microporous aggregates formed a better aggregate/matrix interface bonding and an improved distribution of SiC whiskers. The SiC whiskers formed not only in the matrix, but also inside of the microporous aggregates and at the aggregate/matrix interface by a vapor‐solid reaction mechanism. Due to the formation of a microporous aggregate/matrix interface reinforced by SiC whiskers, the crack propagation along the aggregate/matrix interface was suppressed, whereas the percentage of cracks propagating within the aggregates was enhanced. Thus, the synergy between in situ formed SiC whiskers and microporous aggregates resulted in a significant higher strength of lightweight Al₂O₃–C refractories compared to conventional ones. The results therefore provide an original strategy to strengthen Al₂O₃–C refractories.

中文翻译：

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控制钢水流动的轻质氧化铝碳质耐火材料的新方法

用于连续铸造的钢水流量控制装置的功能耐火材料，通常是由含有致密刚玉骨料的Al ₂ O ₃ -C耐火材料制成的。根据传统概念，耐火材料越稠密，耐火材料的强度就越高。但是，我们使用微孔刚玉骨料代替致密刚玉骨料制备了一种新型的轻质Al ₂ O ₃ -C耐火材料，并通过原位形成的SiC晶须进行了增强。对常规和轻质Al ₂ O _3的组织和性能进行了比较分析含和不含硅粉的–C耐火材料。我们表明，微孔聚集体形成了更好的聚集体/基体界面结合，并改善了SiC晶须的分布。SiC晶须不仅在基体中形成，而且在微孔聚集体内部以及聚集体/基质界面处通过汽固反应机理形成。由于形成了由SiC晶须增强的微孔聚集体/基体界面，因此抑制了沿聚集体/基体界面的裂纹扩展，而裂纹在聚集体内的传播比例得到了提高。因此，原位形成的SiC晶须与微孔聚集体之间的协同作用导致轻质Al ₂ O _3的强度明显提高。–C耐火材料与常规耐火材料相比。因此，结果为加强Al ₂ O ₃ -C耐火材料提供了一种原始策略。