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ISSN Online: 2377-424X

ISBN Print: 0-89116-299-2

International Heat Transfer Conference 7
September, 6-10, 1982, Munich, Germany

INFLUENCE OF OXIDATION ON THE RADIATIVE PROPERTIES OF STAINLESS STEELS AS A FUNCTION OF TEMPERATURE

Get access (open in a dialog) DOI: 10.1615/IHTC7.3980
pages 463-467

Résumé

Spectral directional factors such as the emis sivity ελ or the reflectivity ρλo iso are functions of the radiation wavelength λ ,the direction of emission Δ , the temperature T and the surface state of the material. Avoiding the influence of roughness by an optical burnishing of the surface we investigated the influence of oxidation on the emissivity of 304 L and 316 stainless steels. We use two experimental technics ; in the first one ελ is measured for 2< λ < 14 µm and 500 < T < 1000 K in the second one , ρλ oiso is determined for 0,4 < λ < 1µ and 200 < T < 1000 K. Experiments are made under primary vacuum or in the air. Experiments show that temperature has no influence upon ελ for a given state of oxidation while oxidation deeply increases the spectral emissivity and modifies the aspect of the curves of ελ as a function of the angle of emission in the visible range. Computation of optical indices of refraction n and extinction κ. from the measured ελ using the Fresnel theory, is possible only if there are no oxide layers or if they are transparent at the considered wavelength.