SPECTRAL EMITTANCE AND TEMPERATURE DETERMINATION OF CARBON SIC AND SIC/SIC COMPOSITES/

The radiation comparison method is used to measure the total normal an d spectral emittance in the range 1000 K to 2000 K. Problems of measur ement uncertainties mainly resulting from temperature measurement erro rs are discussed. Results of measurements on Carbon/SiC and SiC/SiC fi ber/matrix composites show values in the range 0.7 to 0.9 without a sy stematic dependency on fiber material or orientation. The new evaluati on method for the integral six-color pyrometer is used to automaticall y calculate the true temperature from the measured radiance temperatur es. The variation of the emittance epsilon with wavelength can be expr essed as an exponential function with one, two, three or four coeffici ents. An averaging method is used to find the correct surface temperat ure. Deviations between calculated and experimentally determined surfa ce temperatures were found to be between 1 and 2%.