Experimental Study on thermal Radiation Characteristics of Metallic Materials in Actual Environments of Industry

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The present project investigates the thermal radiation characteristics of metallic materials in the actual environments of industry, on a basis of spectral experiments. A high-speed spectrometer system is developed firstly, to measure the transient behaviors in the characteristics, so that it can measure the spectra of the near-ultraviolet to the infrared repeatedly at every 0.93 second. Interference phenomenon of radiation is found to appear not only in the specular reflection spectra of oxidizing specular surfaces but also in the diffuse reflection spectra of oxidizing rough surfaces. The phenomenon are fairly clear and reproduced well, which suggests a possibility of the theoretical study characterizing the radiation characteristics of real surfaces of metallic materials. Secondly, an idea relating to the surface scattering of electro-magnetic radiation is presented as a theoretical basis for the characteristics. The interference and diffraction are discussed for a element, in which an absorbing film with three-dimensionally non-parallel interfaces is formed on a metallic substrate of an order of the wavelength of radiation. Boundary conditions at a two-medium interface are described generally for the infinitely wide system. The results are applied to a non-parallel film element model with the Kirchhoff's diffraction theory. Third, a three-dimensional surface model is presented to describe the thermal radiation characteristics of real surfaces of metallic materials roughend and/or oxidized in industry. The algorithm is based on an idea of the supperimposed multiplily-dispersed facets. It is combined with that of the above film element model. The interference and diffraction of radiation are investigated. Numerical computation is performed to examine tha radiation models for the qualitative discussion on the experimental results.