Phase Formation Specifics in the High-Alumina Region of the СаО–Al2О3 System

Autor: M. A. Trubitsyn, L. V. Furda, M. N. Yapryntsev, N. A. Volovicheva
Rok vydání: 2022
Předmět:
Zdroj: Russian Journal of Inorganic Chemistry. 67:1308-1318
ISSN: 1531-8613
0036-0236
DOI: 10.1134/s0036023622080277
Popis: Abstract Phase formation of calcium monoaluminate and calcium dialuminate in the СаО–Al2О3 system in the range 230–1450°C was studied using a model powder mixture comprising aluminum and calcium hydroxides. The onset of formation of an intermediate phase Ca12Al14O33 (С12А7) was observed at 430°С. At 1100°С, the appearance of CaAl4O7 (CA2) and the presence of κ-Al2O3 were observed. The onset of intense formation of the CaAl2O4 (СА) phase is at 1170°С. In the range 1250–1400°С, the CA amount increases notably, while the СА2 proportion remains almost unchanged. The final formation of the CA and CA2 target phases occurs in 2 h at 1450°С. The syntheses of CA and CA2 is controlled by Ca2+ diffusion inward the aluminum-enriched cores of spherulites. Energy dispersive X-ray spectroscopy elucidated the CA and CA2 distribution in the form of concentric layers.
Databáze: OpenAIRE
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