The Normal Spectral Emissivity Characteristics Research Of Cobalt

Metallic cobalt is one of the most important magnetic materials.With its superior characteristics such as high strength,permanent magnetism,and thermostability,metallic cobalt is widely applied in chemical equipment,heat-resistant,atomic energy and electronics industries.In the process of metal material development and smelting,it is particularly important to accurately measure the thermal physical parameters and temperature of the material.Its measurement accuracy will directly affect the properties and quality of the smelting metal.But the spectral emissivity is not a fixed value,which will be affected by wavelength,temperature,surface conditions and other factors.If any of these conditions are changed,the spectral emissivity will be greatly affected even for the same material.Therefore,it is of great practical significance to study the spectral emissivity of cobalt.At present,the spectral emissivity measurement technology involves military stealth material characterization;this kind of measuring instrument is strictly prohibited from foreign countries to our country.The technology has no international or national uniform standards.In recent years,domestic research institutes have carried out research on spectral emissivity measurement technology,and developed a variety of spectral emissivity measurement instruments based on energy method,reflection method and so on.However,as the measurement method is not uniform,the level of instrument development is uneven,so the measurement wavelength range,temperature range and measurement accuracy are quite different.In view of the importance of cobalt and the spectral emissivity of cobalt has no relevant report in China.This paper mainly studies from two aspects based on the technique of spectral emissivity measurement in laboratory for many years.One is the measurement of normal spectral emissivity of solid cobalt,and the influence of surface roughness on spectral emissivity is studied.The second is to set up a device for measuring the spectral emissivity of molten metal.The main research work of this paper is as follows:1.This paper introduces the relevant data of cobalt emissivity reported at home and abroad in detail,summarizes and classifies the measurement methods of spectral emissivity,summarizes the methods of spectral emissivity measurement of molten metal emphatically,and summarizes the advantages and disadvantages of various measurement methods and devices.2.The solid emissivity measuring device based on Fourier-transform spectrometer is introduced in detail and the instrument is calibrated by two temperature blackbody calibration methods.Furthermore,we explore the normal emissivity of cobalt samples with different roughness at 3-20?m under six temperatures,and select four representative roughness samples to further analyze the influence of wavelength,temperature and roughness on the normal spectral emissivity.The normal spectral emissivity of the four samples decreases with increasing temperature when the wavelength was less than 8?m.The normal spectral emissivity difference of four samples at different temperatures increases with increasing wavelength at wavelengths greater than 15?m.11.5?m is the intersection of the spectral emissivity curve,which is also called the X point.The normal spectral emissivity of cobalt increases with the increase of surface roughness,which is particularly evident at shorter wavelengths.An improved model is proposed for the cobalt roughness function based on the Agababov roughness function.Using this model,it is possible to deduce the normal spectral emissivity of cobalt samples with different roughnesses.3.Based on the advantages of fast optical fiber spectrometer and high electromagnetic heating speed,a set of molten metal spectral emissivity measuring device is built.The apparatus realizes the real-time measurement of metallic cobalt spectral emissivity,which is mainly composed of blackbody,electromagnetic heater,near-infrared spectrometer and optical system.The spectrometer is calibrated by multi-temperature blackbody calibration method.A new algorithm is used to calculate the spectral emissivity to reduce the influence of background radiation.The normal spectral emissivity of metal cobalt in near-infrared wavelengths at melting point is further investigated and compares with the data reported in the literature to verify the reliability of the device.The research in this paper further enriches the spectral emissivity of cobalt and provides important data support for its research and development.