Direct Measurements of Infrared Normal Spectral Emissivity of Solid Materials for High-Temperature Applications

A new facility for the measurement of the normal spectral emissivity of solid materials for high-temperature applications in the thermal steady state was developed at the Bundeswehr University of Munich. The measurements are performed under atmospheric conditions. The facility covers the temperature range between 500∘C\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$500\,^{\circ }\hbox {C}$$\end{document} and 1350∘C\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$1350\,^{\circ }\hbox {C}$$\end{document} and wavelengths between 0.6μm\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$0.6\,\upmu \hbox {m}$$\end{document} and 15μm\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$15\,\upmu \hbox {m}$$\end{document}. The principle of operation involves the spectral comparison of a test sample with a reference blackbody and the sample surface temperature determination with a numerical spectral ratio calculation. The optical characteristics of the blackbody and the sample surface temperature determination are discussed in detail. Furthermore, measurement results of the quasi-reference material silicon-carbide under steady-state conditions are presented to validate the measurement method.