Abstract The formation and transition of calcium aluminate and calcium silicate compounds from pre-synthesized mullite in low-calcium system were systematically studied by solid-state reaction at 1350–1500 °C using XRF, XRD, FTIR, SEM and PSD methods. Ca3Al2O6, Ca12Al14O33, CaAl2O4, Ca2SiO4 and Ca2Al2SiO7 can form via direct reaction of mullite with CaO at the beginning of the reactions, then Ca12Al14O33 and Ca3Al2O6 react with mullite to form CaAl2O4 and Ca2SiO4, and finally Ca2Al2SiO7 reacts with CaO to generate Ca2SiO4 and calcium aluminate compounds as the sintering process proceeds. Elevating the sintering temperature is in favor of the formation of Ca12Al14O33, Ca3Al2O6 and Ca2Al2SiO7 at the initial reaction stage, but Ca2Al2SiO7 cannot totally transform to calcium silicate and calcium aluminate compounds in the low-calcium system, which deteriorates the pulverization performance of the final products. Increasing the calcium dosage accelerates the transformation of Ca2Al2SiO7 to Ca12Al14O33, CaAl2O4 and Ca2SiO4, which enhances the pulverization performance. If the CaO/Al2O3 molar ratio exceeds 1.4, Ca3Al2O6 will generate by the reactions of pre-formed CaAl2O4 and Ca12Al14O33 with excessive CaO.

中文翻译：

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预合成莫来石固相反应在低钙体系中铝酸钙和硅酸钙化合物的形成和转变

摘要 采用 XRF、XRD、FTIR、SEM 和 PSD 方法，在 1350–1500 °C 下通过固相反应系统地研究了低钙体系中预合成莫来石中铝酸钙和硅酸钙化合物的形成和转变。Ca3Al2O6、Ca12Al14O33、CaAl2O4、Ca2SiO4和Ca2Al2SiO7可以通过莫来石在反应开始时与CaO直接反应形成，然后Ca12Al14O33和Ca3Al2O6与莫来石反应生成CaAl2O4和Ca2SiO4，最后与Ca2Al2SiO7反应生成Ca2Al2SiO7和Ca2Al2SiO7钙随着烧结过程的进行。提高烧结温度有利于初始反应阶段Ca12Al14O33、Ca3Al2O6和Ca2Al2SiO7的形成，但Ca2Al2SiO7在低钙体系中不能完全转化为硅酸钙和铝酸钙化合物，这会降低最终产品的粉碎性能。增加钙用量可加速Ca2Al2SiO7向Ca12Al14O33、CaAl2O4和Ca2SiO4的转化，从而提高粉碎性能。如果 CaO/Al2O3 摩尔比超过 1.4，预先形成的 CaAl2O4 和 Ca12Al14O33 与过量的 CaO 反应生成 Ca3Al2O6。