Development of High-Speed Spectroscopy for Measurement of Thermal Radiation Phenomena of Surfaces

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Real surfaces in actual natural/industrial environments are far different from clean optically smooth surfaces in laboratories. The surfaces have microscopic roughness and they are covered by any surface films in most cases. Furthermore, microstructure of the real surface changes from time to time in the crude environments. Recently, physical/chem-cal processes, in which surface state is positively changed, has been put into practical use. We should make a spectroscopy research in order to clarify thermal radiation charac-teristics of such a real surface for heat transfer evaluation or in order to establish a new surface diagnosis technique using radiation.First, we improved our high-speed spectrophotometer system which measures reflection and emission spectra over a wide spectral reagion from near-ultraviolet to infrared (0.32〜14 μm) in one system simultaneously and repeatedly with a cycle time of 1 s. Second, we used this experimental system in a wavelength region of λ=0.32〜11 μm to measure the transition of reflection and emission spectra of metal surfaces in an air-oxidation process at high temperatures. Measured phenomena of radiation interference and diffraction suggested the mechanism of oxide film growth and roughness creation on the film surface. Third, taking note of this phenomena, we presented/improved an algorithm of an in-process surface diagnosis technique for diagnosing the surface temperature and surface micro-structure of real metal surfaces based on a high-speed spectrum measurement. An experimental examination of the surface diagnosis is made on a metal surface in an air-oxidation process at high temperature, and the ability of the presented technique is demonstrated.