High-temperature emissivities of copper, aluminum, and silver

Abstract

Using a transient calorimetric technique, the total hemispherical emissivities ∊_h of very pure copper, aluminum, and silver have been measured at various temperatures in the range 335–1100°K. By carrying out measurements on a sphere, a thin circular disk, and a thin square plate all made of the same copper sample, it is shown that the measured ∊_h is practically independent of the shape of the specimen. Measured ∊_h values of Cu, Al, and Ag show considerable departure from the theoretical predictions of Davisson and Weeks and the data of previous investigators. ∊_h data are presented in tabular form at 20°K intervals for all three materials in the range 400–1000°K.