Development of An Apparatus for the Directional Spectral Emissivity Measurement from 50 ℃ to 1000 ℃

To realize precise directional spectral emissivity determination of solid materials under the atmosphere, an apparatus what covers the temperature region from 50 °C to 1000 °C and a spectral range of 3 μm–14 μm was developed. The measurement angle can be adjusted from 0° to 60° utilizing a stepper rotary stage. The reliability of the apparatus’s reliability was confirmed by measuring the spectral emissivity of a SiC sample at high temperatures. Furthermore, the normal spectral emissivity of SiC was investigated from 50 °C to 1000 °C, and the directional spectral emissivity at 600 °C and 800 °C was shown. The influence of temperature and measurement angle on the spectral emissivity of SiC was analyzed in detail. Additionally, the cause of the silicon dioxide film on the surface of SiC after high temperature heating and its influence on spectral emissivity were explored. Finally, a detailed analysis of the uncertainty components of the emissivity measurement under varying temperatures and wavelengths was performed, and the results showed that the uncertainty of the apparatus was better than 0.05 in its measurement range.