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Thermal Conductivity of Uranium Dioxide from ‐57° to 1100°C by a Radial Heat Flow Technique
Author(s) -
GODFREY T. G.,
FULKERSON W.,
KOLLIE T. G.,
MOORE J. P.,
McELROY D. L.
Publication year - 1965
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1965.tb14745.x
Subject(s) - thermal conductivity , uranium dioxide , atmospheric temperature range , analytical chemistry (journal) , impurity , debye model , thermocouple , materials science , crystallite , electrical resistivity and conductivity , heat flow , thermal diffusivity , thermodynamics , chemistry , uranium , thermal , composite material , metallurgy , chromatography , electrical engineering , engineering , physics , organic chemistry
A radial heat flow technique was used to measure the thermal conductivity, k , of polycrystalline UO 2 in the range ‐57° to 1100°C. The technique yielded results with a probable accuracy of ±1.5% and a precision of ±0.1% in the range 50° to 1100°C. Meaningful measurements were limited to 1100°C by Pt‐90 Pt10Rh thermocouple instability, although the apparatus was structurally sound to 1400°C. The thermal conductivity data up to 1000°C could be explained on the basis of heat transport by phonons. The thermal resistance, l/ k , exhibits a linear temperature dependence from 200° to 100°C, which is expected for an insulator well above the Debye temperature. The slope of the l/ k ‐temperature plot is 0.0223 cm w −1 which is independent of impurity content and is associated with three phonon umklapp processes. The intercept is sensitive to impurity content as indicated by the fact that it was decreased by a decrease in the oxygen/uranium ratio. Between 1000° and 1100°C, there is a slight departure of l/ k from linearity which may be due to the onset of an electronic contribution. Near room temperature, UO 2 has a maximum in k which is apparently caused by the rapid decrease in specific heat below this temperature.