Restructuring-diffusion mechanism of calcium alumino-titanate in CaAl12O19–MgAl2O4–Al2O3 castables

Abstract

Calcium alumino-titanate (CAT), a secondary material obtained from ferrotitanium slag, was used as a hibonite source to prepare CaAl 12 O 19 –MgAl 2 O 4 –Al 2 O 3 castables. The restructuring effect of CAT aggregate was compared by replacing tabular alumina aggregates with CAT aggregates of different particle sizes. The effects of CAT particle size on cold mechanical strength and thermal shock resistance of CaAl 12 O 19 –MgAl 2 O 4 –Al 2 O 3 castables were studied. The results showed that CAT aggregates with particle size of 5–3 or 3–1 mm led to more internal cracks or pores and reduced the cold mechanical strength of the castable samples fired at 1600 °C for 3 h. The use of CAT aggregates with particle size of 1–0 mm led to the formation of a well-bonded CAT aggregate and matrix, improving the cold mechanical strength and thermal shock resistance of the castable samples fired at 1600 °C for 3 h. The enhancement mechanism of fine CAT aggregates in this process was proposed based on the sintering of the matrix–aggregate interface with the formation of Ca(Al, Mg, Ti) 12 O 19 .