Experimental Investigation of Spectral Emissivity of Copper-Nickel Alloy During Thermal Oxidation Process
XU Yan-fen1, ZHANG Kai-hua1*, LIU Yan-lei1, YU Kun1, LIU Yu-fang1, 2*
1. College of Physics, Henan Normal University, Xinxiang 453007, China
2. School of Optics and Photonics, Beijing Institute of Technology, Beijing 100081, China
Abstract：With the development of science and technology, the requirements for the quality of copper-nickel alloy products rise rapidly in the industrial field. During smelting and processing of copper-nickel alloy, the quality of products depends on the accurate surface temperature measured by radiation thermometry.Therefore,it is particularly important to study the spectral emissivity characteristics of copper-nickel alloy. In this paper, the spectral emissivity of the copper-nickel alloy is measured by the apparatus based on a Fourier transform infrared spectrometer at four temperatures (673, 773, 873 and 973 K) over the spectral range from 2 to 22 μm. The effects of wavelength, temperature, heating time and oxidation on the spectral emissivity of copper-nickel alloy are studied. It was found that the spectral emissivity of the copper-nickel alloy increased with increasing temperature and decreased with increasing wavelength in a nitrogen environment. When copper-nickel alloy was exposed to an air environment, its spectral emissivity increased rapidly with temperature. At 673 K, a layer of tinoxide particles was formed on the surface, which prevented further oxidation of copper-nickel alloy. The spectral emissivity of oxide particles is higher than that of copper-nickel alloy, so the spectral emissivity at a short wavelength increases slightly. At 773 K, the phenomenon of copper-nickel alloy’s surface gradually turned red was observed during the experiment. It is found that Cu2O is the main component of the surface oxide, which is the reason why the spectral emissivity of the copper-nickel alloy increases rapidly. At 873 K, the type and content of oxide increase obviously, and oxide film thickness satisfies the condition of interference effect. The evolution of the interference extremum can be obviously observed in the spectral emissivity curves of copper-nickel alloy, and the interference extremum gradually moves to long-wavelength with the increasing of heating time. The oxidationresistanceof copper-nickel alloy decreases with increasing temperature. At 973 K, the oxidation degree on the surface of copper-nickel alloy is the deepest, and the peak value of oxide in the XRD pattern is the largest. Therefore, the number of interference extremum is most due to interference effect after 1 h. In conclusion, the spectral emissivity of the copper-nickel alloy is significantly influenced by wavelength, temperature and oxidation, which should be considered in the application of radiation thermometry.This study enriches the spectral emissivity of copper-nickel alloy and provides reliable data support for radiation thermometry.
Key words：Copper-nickel alloy; Spectral emissivity; Oxidation; Temperature; Heating time
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