Stabilization of thermal storage ceramics via the phase reconstruction of ferrotitanium slag and migration of Mg element

Abstract

In this study, aluminum titanate/anorthite (Al₂TiO₅-CaAl₂Si₂O₈) ceramics were fabricated from ferrotitanium slag through phase reconstruction. Stabilization of the ceramic was achieved by migration of Mg element into Al₂TiO₅ phase. The results indicated that optimal performance was achieved with the addition of 4 wt% MgO and 60 wt% ferrotitanium slag at 1370°C. The ceramic exhibited bulk density of 3.11 ± 0.01 g/cm³, thermal storage density of 1.51 kJ/cm³, and thermal expansion coefficient of 3.40 × 10⁻⁶/°C (1000°C), respectively. Additionally, the solid solution of Mg²⁺ in the Al₂TiO₅ lattice reduced the formation of microcracks and enhanced the mass transfer process. Consequently, the sintering temperature decreased from 1415°C to 1370°C while the bending strength increased from 61.25 ± 1.05 MPa to 75.92 ± 7.72 MPa. Furthermore, finite element simulation demonstrated that higher thermal expansion led to concentrated thermal stress, potentially increasing the possibility of ceramic cracking. This research provides a new strategy for preparing low thermal expansion ceramics from titanium-containing solid waste.