Thermal Conductivity of Some Ceramic Materials at Cryogenic Temperatures

Abstract

The application of ceramics in cryogenic systems is expanding. Thermophysical properties of these ceramics in cryogenic temperatures are thus needed. In this investigation, the thermal conductivities of 7740 Pyrex, 99.99% purity dense Alumina, and dense 8% mol yttrium-stabilized zirconia (YSZ) were experimentally measured in the 75–300 K temperature range, using the guarded comparative-longitudinal heat flow technique in accordance with ASTM International's ASTM E1225-13 standard. These ceramics are widely applied in cryogenics systems, including some critical components of Stirling and pulse-tube cryocoolers. The measured conductivities for Pyrex are in general agreement, but slightly higher than available published data. The data for 99.99% purity dense alumina agree with data from two previously published sources in the aforementioned temperature range. Our experimental thermal conductivity data for dense 8% mol YSZ appear to be the first such data in the aforementioned temperature range and indicate a temperature-sensitive distribution with a peak at about 140 K temperature. The data also converge with two sets of previously published experimental data representing temperatures lower and higher than the aforementioned temperature range. Empirical correlations are developed for the thermal conductivity of 7740 Pyrex and 99.99%—purity dense alumina for the 75–300 K temperature range based on our experimental data. Empirical correlations are also proposed for the 40–400 K temperature range for 8% Mol YSZ, based on the experimental data generated in this work as well as the data from two other sources.