基于基尔霍夫定律,利用砷化镓(GaAs)半导体激光器作为标准光源研制了一种能够准确实时测量不透明物体光谱发射率的反射式测量装置.利用该装置在300~1 123 K之间对黄铜和紫铜两种样品在波长1.55 μm处的光谱发射率进行了系统的研究,探讨了温度、氧化、加热时间等因素对两种铜样品光谱发射率的影响.实验结果表明:黄铜和紫铜的光谱发射率均随温度的升高而增大,并且紫铜的光谱发射率始终大于黄铜的光谱发射率,两种样品随温度的光谱发射率曲线均出现了峰值和谷值.通过分析有氧化膜时金属表面的反射模型,得到了金属表面氧化膜厚度的计算公式,并利用该公式估算了紫铜发射率出现峰值和谷值时氧化膜的厚度.恒温长时间测量结果表明:光谱发射率随加热时间出现小幅增大,2 h后,由于样品表面氧化达到一定程度,氧化速率开始变缓,样品表面的光谱发射率也随之开始趋于稳定.样品在较高温度处的光谱发射率数值始终大于较低温度处的发射率数值.该研究进一步丰富了铜的光谱发射率数据,并为其光谱发射率的应用提供了实验依据.

In this study,a new reflective experimental apparatus,which can measure the spectral emissivity of opaque materials accurately and real timely,has been developed based on the Kirchhoff’s law by using the GaAs semiconductor laser as the standard radiation source.The spectral emissivity of brass and red copper at wavelength λ=1.55 μm were investigated systematically with the temperatures range from 300 up to 1 123 K by using this apparatus and the influence of temperature,oxidation and heating time on the spectral emissivity of two kinds of specimens were also discussed.The experimental data showed that the spectral emissivity increased with increase of temperature and appeared its peak value and valley value when the thickness of oxide film was at some degree.The spectral emissivity of red copper was always greater than that of brass.The formula for calculating the thickness of oxide film was derived from the reflection model composed of a metal and oxide film,then the peak and valley thickness of the red copper were estimated according to this model.The experimental data of constant temperature measurements showed that the spectral emissivity had a slight increase with heating time increasing.Two hours later,the spectral emissivity of two kinds of samples trended to be stable when the thickness of oxide film was at some degree.The values of spectral emissivity at high temperatures were always larger than that of low temperatures.The results of this study will further enrich spectral emissivity data of copper and provide experimental basis for its application.