Review of Techniques for Thermophysical Property Measurements at High Temperature

Abstract

The methods available for the measurements of the following thermophysical properties of high temperature melts are reviewed viz. density, viscosity, surface tension, heat capacity, enthalpy, thermal diffusivity and conductivity, electrical conductivity and emissivity. The methods are illustrated with reference to work carried out on molten silicon. In order to combat contamination of the melt from container/sample reactions there has been a gradual switch to the use of (i) containerless methods employing various forms of levitation or microgravity (drop towers, parabolic flights and space experiments) and (ii) sub-second rapid heating and other non-intrusive techniques. However, there are other equally-important conditions which must be addressed to obtain accurate property values, e.g. the control of oxygen partial pressure in surface tension measurements and the selection of the most reliable method to analyse data. It is our contention that equal attention should be given to these problems.