TOTAL HEMISPHERICAL EMITTANCE MEASUREMENTS OVER THE TEMPERATURE RANGE 77 deg K TO 300 deg K
Technical documentary rept.
NAVAL RADIOLOGICAL DEFENSE LAB SAN FRANCISCO CA
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Total hemispherical emittance measurements were made on a series of high emittance black paints, metal blacks and anodized aluminum over the temperature range from 77 deg K to 300 deg K by measuring the rate of temperature decay of a coated disk in a vacuum. Analytical and experimental analysis show that errors inherent in the method are less than 1 of the emittance of a black body at the temperature of the measurement, although instrumental errors and uncertainties in the heat capacities of the specimens reduce the accuracy of the reported data to -10. The blackest material measured was electrically deposited platinum black on gold. The emittance of a black paint appeared to be more dependent on the thickness that it could be applied than on the specific type of paint. Heavily anodized aluminum exhibited an emittance near 77 deg K of about 0.6, nearly as high as the best black paints, although it looked bright to the eye. The best platinum black coating had an emittance above 0.9 at 77 deg K. The metal blacks and the black paints had emittances above 0.95 at room temperature.