The tungsten-copper alloy is commonly used for the electrical contact in high current vacuum switch, where precise temperature monitoring of the contact is crucial for ensuring stable operation of the switch by radiation thermometry. However, accurate emissivity data of this alloy is necessary when using radiation thermometry for temperature measurement. Thus, the directional spectral emissivity of tungsten-copper alloy is investigated within the temperature range of 400–700 ℃ under vacuum in this work. The hemispherical total emissivity is calculated by numerically integrating the directional spectral emissivity. Experimental results found this tungsten-copper alloy agrees with the theoretical prediction of the electromagnetic theory, that is, the emissivity increases with increasing temperature, and decreases with increasing wavelength. A convergence phenomenon of spectral emissivity occurs when the polar angle exceeds approximately 50°. This means that the normal wavelength dependence undergoes a shift at high polar angles, which is typical behavior of metallic emissivity. Additionally, the effects of thermal cycle, surface roughness, and chemical composition on emissivity are analyzed in detail. Surface stress relaxation process results in a significant decrease in emissivity. Emissivity increases as the surface roughness and tungsten composition of alloy increases. However, the effects of surface roughness and chemical composition on emissivity gradually disappear at long wavelengths and high polar angles.

钨铜合金常用于大电流真空开关的电触点，通过辐射测温技术对触点进行精确的温度监测对于保证开关的稳定工作至关重要。然而，当使用辐射测温法进行温度测量时，需要该合金的准确发射率数据。因此，本工作在真空下研究了钨铜合金在400~700 ℃温度范围内的定向光谱发射率。通过对定向光谱发射率进行数值积分来计算半球总发射率。实验结果发现，这种钨铜合金的发射率与电磁理论的理论预测一致，即发射率随着温度的升高而增加，随着波长的增加而降低。当极角超过约50°时，会出现光谱发射率的收敛现象。这意味着正常波长依赖性在高极角下会发生变化，这是金属发射率的典型行为。此外，还详细分析了热循环、表面粗糙度和化学成分对发射率的影响。表面应力松弛过程导致发射率显着降低。发射率随着合金表面粗糙度和钨成分的增加而增加。然而，表面粗糙度和化学成分对发射率的影响在长波长和高极角下逐渐消失。