A survey of hemispherical total emissivity of the refractory metals in practical use

The applicability of the hemispherical total emissivity measurement for metals those have a thin protective layer (passive scale) on its surface was investigated at high temperatures (above 1000 °C) using a modified hot-filament method. In this method, the Joule heat and the temperature of the specimen were measured by two sets of electrodes (two sets of thermocouples) spot-welded at the middle portion of the specimen, in order to reduce the influence of heat loss from the water cooled electrodes at both ends of the ribbon specimen.