SPECTRAL-DIRECTIONAL EMITTANCE OF THERMALLY OXIDIZED 316-STAINLESS-STEEL

The spectral-directional emittance of thermally oxidized stainless ste el is measured for angles from normal to grazing, wavelengths between 2 and 10 mu m, and temperatures between 773 and 973 K. The oxide is gr own by holding the steel substrate at a high temperature over a long p eriod while exposed to normal atmospheric conditions, until the measur ed emissive power of the surface achieves an asymptotic level. It is f ound that the emittance decreases with angle away from the surface nor mal at the lower end of the measured spectral range and increases with angle al the higher end. The emittance decreases with wavelength, alt hough there is evidence of a peak near 2 mu m. The variation with temp erature within the measured range is insignificant. Overall higher val ues for the oxidized steel are measured than those reported in previou s work.