Preparation and Thermal Shock Behavior of Low‐Silicon Alumina‐Mullite Composites

ABSTRACT Despite their high‐temperature stability, alumina crucibles used in industries exhibit poor thermal shock resistance. To improve the comprehensive performance of alumina crucibles, the effects of different silica sources and sintering temperatures on the mechanical properties and thermal shock resistance of alumina ceramics are studied. The experimental results show that the addition of 5 wt% silica sol (30 wt%) and sintering at 1550°C improves the comprehensive properties of alumina–mullite composite ceramics, achieving a bulk density of 3.56 g/cm 3 , compressive strength of 260.5 MPa, and flexural strength of 373.68 MPa. After five cycles of thermal shock tests, the highest residual strength ratio is 56.18%, indicating improved thermal shock resistance. These results are significant for the production of new alumina crucible materials for the smelting of alloys.