Resistance, Emissivities and Melting Point of Tantalum

The relation between true and brightness temperatures of tantalum was determined by means of pyrometric observations on the inside and outside of a long thin-walled tube heated electrically. The brightness temperature as a function of heating current was determined by sighting on an electrically heated wire of known diameter. Potential leads of fine tungsten wire welded to tantalum filaments permitted a determination of the electrical properties as a function of temperature. The electrical properties at the melting point yielded a value for this quantity from the extrapolated temperature vs. electrical property relations. Value for the melting point determined is 3269°K.