Radiation heating test and development of porous MgAl2O4 ceramics with high thermal shielding effect based on Mie theory

Abstract Porous MgAl 2 O 4 ceramics designated as THERMOSCATT TM have diffuse reflectance based on the Mie theory. The reflectance greatly suppresses radiation heat transfer and has low emissivity at 1–5 μm wavelengths. Their thermal conductivity has been measured as less than 0.3 W/(m K) at 1500°C. Furthermore, porous MgAl 2 O 4 ceramics have near‐zero hemispherical spectral emissivity values at 0.35–5 μm wavelengths. High heat resistance and low emissivity materials in the atmosphere are useful for the innermost layer of industrial furnaces to confine energy efficiently. Additionally, this material is useful as a radiation reflectors, such as in stand‐off thermal protection systems. This study elucidated the suppression of radiation transfer in porous MgAl 2 O 4 ceramics attributable to low thermal emissivity. Therefore, the thermal insulation performance under radiation heating in vacuum, the emissivity validity evaluation of low‐emissivity porous materials using finite element analysis, and microstructure effects on radiation heating performance and mechanical properties were investigated.