Study of the Radiative Properties of Heat Resisting Metals and Alloys : (1st Report, Optical Constants and Emissivities of Nickel, Cobalt and Chromium)

Infrared reflectivities and emissivities of nickel, cobalt and chromium are measured at high temperatures. Cobalt is found to have a remarkable hysteresis of emissivity around the martensitic transformation temperature. An optical dispersion equation is applied to describe the spectral characteristics of interband transitions and conduction absorption of electrons of these three metals. Quantitative expressions for the parameters in the equation are obtained for temperatures up to 1700, 1400 and 1000 K for nickel, cobalt and chromium, respectively. Spectral and total emissivities are calculated as functions of temperature and crystal phase.