THE PRECISE DETERMINATION OF THERMAL CONDUCTIVITY AND ELECTRICAL RESISTIVITY OF SOLIDS AT HIGH TEMPERATURES BY DIRECT ELECTRICAL HEATING METHODS.

Direct electrical heating methods possess desirable features for determinations of thermal conductivity values to high temperatures. Since unreliable data have been obtained by previous workers using these methods, a systematic evaluation of the various techniques was initiated. An apparatus capable of providing a variety of thermalelectrical boundary conditions to a single specimen as prescribed by particular techniques was designed and fabricated. With this apparatus thermal conductivity, and other thermophysical properties, can be determined on a single specimen by various methods, permitting direct evaluation and comparison of the results. In connection with this experimental effort, the theoretical models of the methods and analyses of the conditions which must be met in the experimental apparatus are being studied. The ultimate objective of the program is to devise a techniques suitable for determinations to temperatures of the order of 2500 C, utilizing test specimens of simple geometry and minimum volume. Author