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Thermal emissivity and high-temperature stability of thermal insulating materials produced by mixing powdered porous MgAl2O4 ceramics with commercial insulating castable

2020 Journal of the Ceramic Society of Japan  
Conventional industrial thermal insulating materials have a porous structure and provide resistance to thermal conduction. However, this structure permits heat transfer through radiation. Hence, they exhibit high thermal conductivity at temperatures higher than 1000°C. To achieve high total-thermal-insulation efficiency, we recently developed new insulating materials, called THERMOSCATT TM , which greatly suppress radiation heat transfer. Their thermal conductivity was measured to be less than
more » ... ed to be less than 0.3 W/(m·K) at 1500°C. These insulating materials consist of porous MgAl 2 O 4 ceramics having 15¯m pores which restrain heat transfer through radiation, which was consistent with the Mie scattering theory. From the thermal emissivity estimated from reflectance measurements, the porous MgAl 2 O 4 ceramics had near-zero hemispherical spectral emissivity values in the wavelength range of 0.355¯m. Mixing these powdered porous MgAl 2 O 4 ceramics with a conventional commercial insulating castable ceramics is shown to successfully reduce heat transfer through radiative Mie scattering. This report describes the experimental result of the powdered porous MgAl 2 O 4 ceramics mixed into the commercial insulating castable.
doi:10.2109/jcersj2.20062 fatcat:7wlf4kl4jbamnblxv4yczrqsvi