Thermal radiation properties of different metals

The thermal radiation properties of different metals are taken over a large temperature range because they are needed as material data for construction and process control of thermal technical plants and for pyrometric temperature measurements. This includes non-ferrous metals and steel for heat up and heat treatment technologies as well as construction metals for high temperature installations and units. Metals are generally used for technical applications as specially alloyed materials, for which the thermo-physical properties in most cases are not sufficient known. That concerns also the radiative properties within the range of higher temperatures, which therefore have to be determined. Based on the treatment and application of metals in higher temperature ranges the emittance is the most qualified radiative property for use in heat transfer calculations and for adjustment of temperature measuring instruments. At the university of Duisburg-Essen measurements of spectral emissivities for a large number of metals are carried out. The measuring systems, based on a monochromator and a FT-IR-spectrometer are described. A survey of results for different metals is given. The influences of temperature and roughness are investigated. Other results lead to the existence of a so called X-point. The oxidation of metals show drastically changes of emissivities. For oxidizing steel the theoretical expected interferences of spectral emissivities could shown by measurements.