A Research On The Spectral Emissivity Of Copper,Iron And Steel

As the increase of industrial automazation and the rise of smart devices,the need of sensor is growing fast,the advance of precision and the scope of application of temperature sensors play a big role in industry and everyday life.The infrared temperature sensors are large in the scope of application and easy to use,so that they play a big role in the temperature sensing field.And the improvement of temperature sensors relies on the improvement of infrared emissivity of materials.In this article,an infrared emissivity measurement device designed by our lab is implemented to study the spectral emissivity of some common metal and their alloys,such as iron,steel,copper and brass..This article introduces the background and meaning of the study of spectral emissivity;the research progression of the spectral emissivity of materials;the spectral emissivity measurement methods and applications.The concepts relevant to the measurement of spectral emissivity is also introduced: the emission of blackbody,Plank’s law,Wien’s displacement law,Kirchhoff’s law,the stern,pan boltzmann’s law,the classification of radiating bodies are presented in this article.Three thermometry methods are also presented in this chapter,using the radiation temperature to determine a body’s true temperature,using brightness temperature to determine a body’s temperature and colormetry temperature measurement method.The principle of the build of blackbody cavity is introduced.Various kinds of definition of emissivity are introduced and equations are presented.Three kinds of energy comparing methods to determine the emissivity of a target are presented in detail: the single optical path method,the dual optical path method and the optical fiber as optical path method.The application used in our laboratory is presented.The environmental factors that could intervene in the measurement of spectral emissivity are also discussed,such as the absorption by carbon dioxide and vapor in the infrared spectrum.The major findings can be concluded as follow:(1)The emissivity of oxidized brass H62,pure copper,steel 201,steel 304 and iron A3 are getting larger as the increase of temperature,and decrease as the increase of wavelength.(2)The oxide of brass at the experimental condition are Zn O,which makes the emissivity of brass significantly lower than that of pure copper.The thickness of the oxide film of brass is estimated to be about 1.64μm using the interference method,the result coincides with the result acquired by ellipsometer.(3)The emissivity of all three iron-based materials increase as the alleviation of temperature,the material with the most chromium composition percentage possesses the lowest spectral emissivity,the spectral emissivity of iron A3 is higher than that of steel 201 and 304 at all temperature points.The results of X ray diffraction shows that the oxide film of steel 201 and steel 304 are stable oxide chromium hemitrioxide,and the spectral emissivity of which tends to be stable.The oxide film of iron A3 is the mixture of unstable oxide ferroferric oxide and ferrous oxide,the composition of the oxide film changes astemperature changes,causing the fluctuation in spectral emissivity values.The spectral emissivity of all three samples peak at around 10μm due to the Christiansen effect.