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

In this study, aluminum titanate/anorthite (Al 2 TiO 5 -CaAl 2 Si 2 O 8 ) ceramics were fabricated from ferrotitanium slag through phase reconstruction. Stabilization of the ceramic was achieved by migration of Mg element into Al 2 TiO 5 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/cm 3 , thermal storage density of 1.51 kJ/cm 3 , and thermal expansion coefficient of 3.40 × 10 −6 /°C (1000°C), respectively. Additionally, the solid solution of Mg 2+ in the Al 2 TiO 5 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.