Study on spectral emissivity characteristics of zirconium alloy tubes for nuclear applications during oxidation
Emissivity is of great significance in the accuracy of non-contact temperature measurement of zirconium alloy tubes and the analysis of heat transfer in the case of water loss accidents. The spectral emissivity data of three zirconium alloys of SZA4,SZA6 and ZIRLO are collected within 4~12 μm during 100 min of oxidation at 400,500 and 600 ℃,and the effect rule of temperature,oxidation film thickness and alloy components on the spectral emissivity properties of material are analyzed. The results show that the emissivity change trends of the three alloys are basically the same during the oxidation process,but the difference in components leads to slight differences in emissivity values and oscillation characteristics. The oscillation phenomenon of spectral emissivity in the wavelength direction is explained by establishing thin-film interference model,and the thickness of the oxide film on the surface of the alloys is calculated by combining the principles of oscillation extremes and interference effects,and the measurement precision of±0. 3 μm is achieved in the range of 0. 6~8 μm.