Experimental Study On Spectral Emissivity Measurement Of High Temeperature Materials

High temperature spectral emissivity of materials is one of the parameters of high temperature thermal properties of materials is the most important,the main parameters influencing the amount of radiation heat exchange under the high temperature condition of heat radiation capacity and spectral distribution,between objects,there is an urgent demand in the field of radiation thermometry,aerospace,energy and energy saving,national defense etc..In this paper,including the background radiation emission rate,high temperature blackbody effective blackbody temperature and sample temperature drop extrapolation of emissivity measurement model.A measurement system for measuring the spectral emissivity of high temperature materials based on the integral black body method is established.The implementation of this system is based on an optimization of temperature field of high temperature blackbody radiation source,high temperature sample crucible,high-speed pneumatic piston linear driving device,linear pyrometer and fiber optic spectrometer,and synchronous circuit.Numerical simulation of temperature change of high temperature sample in the process of high speed linear displacement with complicated heat transfer boundary conditions,a method is proposed for the discretization of the heating tube into a number of isothermal cylindrical rings,and a method for simulating the temperature attenuation characteristics based on the radiative heat transfer network is proposed.The spectral emissivity characteristics of graphite materials at high temperature at 1000?,1300? and 1500? were studied experimentally.