Design, preparation and characterization of multiphase heat storage ceramic balls with high thermal shock resistance

With the improvement of industrial production requirements, the thermal shock resistance (TSR) of the materials used in industrial kilns plays a crucial role in ensuring efficient production. Aluminum-based heat storage ceramic balls (HSCB) are widely used in high-temperature industrial kilns, but they have a problem of weak TSR. A similar situation existed in the HSCB with corundum and Mg-Al spinel phases in our previous research. In this study, corundum-spinel-mullite HSCB was prepared using pre-treated secondary aluminum dross (SAD) as the main material at low roasting temperature. The effects of mullite content on the mechanical properties and microstructure of the HSCB were studied. Mullite whiskers were cross-distributed with corundum and Mg-Al spinel, which benefited the TSR. With the increase of mullite content, the structure of the HSCB gradually became loosely, the TSR increased and then decreased slightly, and linear crack density increased. When mullite content was about 25 %, the comprehensive performance of HSCB performed perfectly. Under the optimal conditions, the coefficient of thermal expansion of the HSCB was only 5.70 × 10 −6  K −1 , the thermal conductivity reached 3.35 W/(m·K) and the TSR was 34 times. This study aimed to provide a theoretical reference for the preparation of aluminum-based ceramic HSCB, as well as to improve the high-value utilization of SAD.