The thermal shock resistance of in-situ synthesized mullite absorption and storage integrated ceramics for solar thermal power generation

Solar high-temperature thermal power generation systems require thermal storage materials with excellent thermal shock resistance due to the large temperature difference during operation (in the range of 20-800 degrees C). In this study, mullite-based absorption and storage integrated ceramics were prepared using low-cost bauxite and kaolin as raw materials and Fe2O3 as additive. The effect of Fe2O3 on the thermal shock resistance of mullitebased ceramics was investigated. The results showed that the absorption and bending strength of sample BK4 (bauxite: 50 wt%, kaolin: 50 wt%, Fe2O3: additional 11 wt%) increased by 2.98% (89.8%) and 8.00% (147.10 MPa), with a storage thermal density of 1185.75 kJ kg-1 after 30 thermal shock cycles. The mechanism for the excellent thermal shock resistance of the ceramics is revealed from the aspect of the changes in phase and microstructure of the samples induced by the changes in the mass transfer rate during the thermal shock process. It was calculated that a unit volume of BK4 (with a raw material cost of about 154.22 USD) could generate 974.95 kW h of electricity (saving 119.92 kg of coal) when used in a solar thermal storage system.