低温状态下的材料法向发射率测量

Measurement of normal emissivity of materials at low temperature

研究了在-60~50℃条件下准确测量材料法向发射率的方法。基于发射率定义建立了材料法向发射率测量模型。为屏蔽环境杂散辐射与大气吸收的影响,利用真空液氮背景通道搭建了低温状态下材料发射率测量装置。测量了氧化铜与高发射率陶瓷两种样品的法向发射率随温度、波长的变化情况。结果表明：两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,氧化铜样品法向积分发射率稳定为0.850±0.012,陶瓷样品的法向积分发射率降低了0.124。最后,实现了低温状态下红外光谱辐射的高精度采集,对低温状态下材料法向光谱发射率测量结果的不确定度进行了评定,得到的结果显示其相对扩展不确定度小于6.0%。

The measuring methods for normal emissivities of materials at-60—50 ℃ was explored.To achieve accurate measurement of normal emissivity of materials at temperature range of-60℃to50 ℃,a measurement model of normal emissivity of materials was established based on the emissivity definition.To shield the effects of environment stray radiation and atmospheric absorption,a measurement facility of the materials at low temperature was built by utilizing a vacuum and liquid nitrogen background channel.The normal emissivities of two samples（copper oxide and high emissivity ceramic）were measured by this facility.The results show that normal spectral emissivities of two samples decrease with wavelengths.Moreover,with temperature increasing,the normal integral emissivity of the copper oxide keeps stable at the range of 0.850±0.012 and that of the high emissivity ceramic reduces by 0.124.Finally,the infrared spectral irradiation was acquired in higher precision at a lower temperature condition,the measurement uncertainty of normal spectral emissivities of materials at low temperature was analyzed.The results show that the relative expanded uncertainty is less than 6.0%.