Heat transfer inhibition of corundum–mullite insulation tiles through composition regulation

Abstract

The increase in size and efficiency of gas turbines leads to higher temperature in the combustion chamber, putting greater demands on the performance of the thermal insulation tiles. Corundum–mullite has been used because of its high-temperature resistance, thermal shock resistance, and low thermal conductivity. However, how to inhibit heat transfer through composition regulation while ensuring the safe use of high-temperature insulation tiles is the key to improving the heat conversion efficiency of gas turbines. In this study, thermal insulation tiles were prepared by casting molding. On the basis of determining the optimal corundum/mullite ratio (22:45 wt%) in the aggregate, the thermal conductivity of the sample was reduced by adding MgO (2 wt%). The results show that phonon intrinsic and defect scattering, caused by changes in phase composition, effectively reduce the thermal conductivity of the insulation tile sample to 2.05 W·m⁻¹·K⁻¹, which is 34.71 % lower than the maximum value before regulation. During 30 cycles of thermal shock (air-cooling at 1000°C), the residual strength gradually decreased and tended to be stable, with a minimum of 8.6 MPa, indicating that the thermal insulation tile can provide better thermal insulation without affecting the safety of gas turbines, providing new ideas and methods for improving the thermal insulation performance of high-temperature thermal insulation materials.