Investigation of the effects of Ni-based alloys DD6 on the normal spectral emissivity during oxidation

摘要

The normal spectral emissivity of Ni-based alloy DD6 during oxidation is experimentally measured at 808, 912 and 998 ℃ for 12 hours in air over the wavelength from 1.35 to 2.35 μm.The estimated standard relative uncertainty of the normal spectral emissivity is less than 5％.The oscillations of the emissivity and the effects of oxidation temperature, heating time and wavelength on the emissivity are investigated.The oscillations of the emissivity are formed by the interference effect between the irradiation from the oxidation film and the irradiation from the substrate.The maximum and minimum of the emissivity shift towards larger wavelengths as the oxidation process continuing.The results show that the normal spectral emissivity increases basically as temperature increases and wavelength decreases except for the occurrence of the oscillations of the emissivity.The changes of the emissivity at different temperatures are pretty different.Besides, the emissivity fitting models versus heating time and wavelength are established, which fit the experiment data very well.The emissivity relative errors of the fitting models are less than 4％.