High-temperature emissivities of copper, aluminum, and silver

Abstract

Using a transient calorimetric technique, the total hemispherical emissivities ε_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 ε_h is practically independent of the shape of the specimen. Measured ε_h values of Cu, Al, and Ag show considerable departure from the theoretical predictions of Davisson and Weeks and the data of previous investigators. ε_h data are presented in tabular form at 20°K intervals for all three materials in the range 400-1000°K.