Measurenent of Emissivities of Metals, Alloys and Materials for Space Station in Space Conditions

在“空间站”的热设计中，需要大量的材料在低温下的半球总发射率数据，而文献中的数据很少，为此，研究了一种材料半球总发射率的测量技术。利用瞬态量热法，发展了一种在短时间内测量半球总发射率的新技术。为了准确测量发射率，在发射率测量装置中加入了保护加热器，并通过细热电偶引线悬挂在试样上进行加热，以减少热损失。通过引线的热损失进行了分析，考虑从引线的辐射和传导传热的组合。分析了试件内部的温度分布。对退火样品进行了测量，发现在170 ~ 350 K温度范围内，机械抛光表面铜的发射率约为0.012 ~ 0.018，而在137 ~ 320 K温度范围内，退火样品的发射率约为0.006 ~ 0.012。

In Thermal design of "Space Station", many data of the total hemispherical emissivities of materials at low temperatures are needed, but we can find a few data in literatures.We studied a measuring technique for the total hemisperical emissivities of materials. Using a transient calorimetric method, a new technique which measure a total hemispherical emissivity within a short period is developed. To measure the emissivity accurately, guard heater is incorporated in the emissivity aparatus and is regurated to reduce a heat loss through fine thermocouple leads suspending a specimen.Emissivity measurements were performed for copper wire as a specimen. The heat losses through the leads were analyzed in considering combined radiation and conduction heat transfer from the leads. Temperature distribution in the specimen were also analyzed. Measurement were also performed with annealed specimen.It was found that the emissivity of copper for mechanical polished surface is about 0.012 to 0.018 in the temperature range 170 K to 350 K, and the emissivity with annealing is about 0.006 to 0.012 in 137 K to 320 K.