高温状态下的材料法向光谱发射率测量

Measurement of normal spectral emissivity of materials at high temperature

为满足隐身材料、热防材料和隔热涂层等高温材料涂层的光谱发射率的高精度测量需求,研究了在1 273 K~3 100 K条件下准确测量材料法向光谱发射率的方法。基于发射率定义,建立了材料法向光谱发射率测量模型,并在该基础上研建了光谱范围为0.7μm~12μm的材料法向光谱发射率测量装置。为克服测量装置中样品高精度加热时伴随腔体效应的技术难点,研制了具备可移动石墨坩埚的样品加热炉,取得了良好的实验效果。使用发射率测量装置对SiC与低发射率涂层2种样品的法向光谱发射率进行实验测量。结果表明:2种样品的法向光谱发射率均随波长增加而降低,随温度的升高而升高。最后对高温状态下材料法向光谱发射率测量不确定度进行了评定,相对扩展不确定度为3.6%。

In order to meet the high-precision measurement requirements of spectral emissivity of hightemperature material coating,including stealthy materials,thermal protection materials,heat insulating coat and so on,the measuring methods for normal spectral emissivity of materials at 1273 K~3100 K was explored.A measurement model of normal spectral emissivity of materials was established based on the emissivity definition.On this basis,the measurement facility of normal spectral emissivity of materials was built,and the wavelength range was 0.7μm to 12μm.In order to overcome the technical difficulties associated with cavity effect when the sample was heated with high precision in the measuring device,a sample heating furnace with a movable graphite crucible was developed,and the good experimental results were obtained.The normal spectral emissivity of two samples(SiC and low emissivity coating)was measured by this facility.The results show that the normal spectral emissivity of two samples reduces with the increase of wavelengths and rises with the increase of temperature.Finally,the measurement uncertainty of normal spectral emissivity of materials at high temperature was analyzed,and the relative expanded uncertainty is 3.6%.