LAUSR

Abstract The normal spectral emissivity of oxidized copper is measured by an experimental setup based on a Fourier transform infrared spectrometer (Bruker 70V) in the wavelength range of 3–20 μm at four temperatures (573 K, 673 K, 773 K, 873 K) during thermal oxidation. Normal spectral emissivity of the samples is obtained every ten minutes for 60 min while the samples are heated at each temperature. The influence of wavelength, temperature, and heating time on the normal spectral emissivity of pure copper during the oxidation process is analyzed. It was found that the spectral emissivity at 12 μm, 15 μm, and 17 μm remained constant for different heating times at 673 K. At the other three temperatures, the normal spectral emissivity demonstrated only a marginal increase with the increase of the heating time at the same wavelength. The oscillation of normal spectral emissivity of pure copper during oxidation was also found. At shorter wavelengths, the theory of radiation interference between the oxide layer and substrate is introduced to explain the spectral emissivity oscillation. In the long wavelength band, the lattice oscillation of the oxide film is used to explain the spectral emissivity oscillation. To better understand these phenomena and the radiative properties of pure copper during thermal oxidation process, the X-ray diffraction, scanning electron microscope and evaluation of surface roughness were performed to describe the compositions and surface micromorphology of the oxide film.