EFFECTS OF TEMPERATURE ON THE SPECTRAL EMISSIVITY OF C/SiC COMPOSITES

Abstract

The effect of temperature on the infrared spectral emissivity of C/SiC composites as a thermal protection material has been studied, using a measurement system based on a FT-IR spectrometer. The spectral emissivity of C/SiC composites in the wavelength range 3-20 μm and in the temperature range from 1000 K to over 2000 K was measured. Based on the analysis of the measured spectral emissivity, variations of the spectral emissivity with temperature were studied. The relationship between emissivity and temperature in some certain wavelength was found.

Review: Thermal ceramic coatings as energy saving alternatives for high temperature processes

“…Although significant effort has been put into this, the measurements of the optical properties at room temperature can be misleading as at high temperatures they will have most likely been critically changed. For example, Figure 10 shows the emissivity spectra of a SiC‐C composite at various temperatures as a function of the wavelength 67,68 . As can be seen, there is a dramatic change in optical properties with the temperature.…”

Radiation heat transfer during hypersonic flight: A review of emissivity measurement and enhancement approaches of ultra‐high temperature ceramics

“…Zhang et al 87 . reported total emittance of C/SiC as a function of temperature ( T in Kelvin unit) by the following polynomial, $$$$\begin{equation}\epsilon \ \left( T \right) = \ 0.727 + \left( {1.548\ \times {{10}}^{ - 4}} \right)T - \left( {8.554\ \times \ {{10}}^{ - 8}} \right){T}^2.\end{equation}$$$$…”

“…Zhang et al 87 (26) These equations aid in the rapid estimation of the emissivity values of corresponding ceramic materials when designing high emissivity refractory ceramics.…”

“…Zhang et al 87 . reported the IR spectral emittance of C/SiC composites in the wavelength range of 3–20 μm and the temperature range from 727–1727°C.…”

A compilation of data on the radiant emissivity of some materials at high temperatures

“…Data for refractory materials and glasses are given in Table A2 [ [33][34][35][36][37][38][39][40][41][42][43][44][45][46]; again many of the polynomial Table A3 lists data for surface coatings. These coatings usually consist of a thin layer of protective refractory against the surrounding atmosphere which is usually oxidative.…”