Fabrication of High-Performance Porous Thermal Insulating Ceramics via High-Proportion Utilization of Industrial Solid Wastes

Large-scale high-value utilization of industrial solid waste is urgently required worldwide. Porous ceramics prepared from single-type solid waste face great limitations in balancing mechanical properties and thermal insulation performance. In this work, various types of industrial solid wastes—red mud, waste electric porcelain, and coal gangue—were fully adopted as primary raw materials, while SiC was employed as a foaming agent to prepare porous ceramics. Results show that at 3% SiC addition and 1140 °C sintering temperature, the apparent porosity of the ceramics reaches to 21.8%, with thermal conductivity of 0.08 W/(m·K). Moreover, favorable pore-size distribution and desirable crystalline phases (Mg–Fe–Al spinel and sodium calcium feldspar) are obtained under this optimal condition, accompanied by a favorable compressive strength of 2.91 MPa, making it a promising low-cost, high-performance high-temperature insulation material.