THERMAL CONDUCTIVITY OF ALUMINUM OXIDE.
Technical rept., 1 Sep 65-31 Aug 66,
CINCINNATI UNIV OHIO MATERIALS SCIENCE PROGRAM
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The method developed earlier in our laboratory to measure thermal conductivity of materials at elevated temperatures has been applied to aluminum oxide. Aluminum oxide discs, 14 to 34 inches in diameter and variable height and grain size, were enveloped along the cylindrical surface in thin 0.001 inches thick platinum foils. The platinum foil was heated by induction to 1500-1800K and it, in turn, heated the aluminum disc through radiation. The temperature distribution along the flat surface of the sample could be divided into two parts toward the center of the sample, only volume lattice and radiation conduction was present at the edge of the sample, the temperature rose rapidly, indicating a finite absorption zone. In this zone, the absorption of the radiation from the platinum heater is not complete yet, and therefore, the temperature distribution and heat transmission in the sample is influenced by the properties of the platinum. Author