THERMAL RADIATION PROPERTIES OF MATERIALS, PART 3
CALIFORNIA UNIV BERKELEY INST OF ENGINEERING RESEARCH
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The effect of temperature on the normal spectral emittance in the range from 1 to 15 microns is demonstrated for certain polished metals and some oxidized and coated metals by a comparison of absorptances measured at room temperature and emittances measured at temperatures of the order of 2000 to 2500 R. The emittances were obtained in a system designed and constructed in the previous phase of this research and these results are affected by the less than optimum operation of this system, by which contamination of the sample occurred, irregularly but consistently. The results for Pt, Ni, and Fe reveal at high temperature the correspondence with the Hagen Rubens law which is implied by available results on the total normal emittance, though the correspondence in this spectral range must be at tributed to anomalous effects. With oxides and with coated materials the effect of temperature on the spectral values appears to be small and localized, though with some materials these are indications of permanent changes in the emittance as the period of exposure to high temperature is increased.