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The thermal diffusivity and specific heat of superplastically deformed 3Y-TZP specimens were measured in a temperature range from 298 to 1273 K. From these data, the thermal conductivity has been evaluated and discussed. A weak temperature dependence of the thermal conductivity was observed. The thermal conductivity showed almost no dependence on the grain size and grain aspect ratio of the 3Y-TZP specimens. On the other hand, the thermal conductivity was considerably sensitive to the deformation-induced cavities. The influence of the cavities on the thermal conductivity is related with temperature. An expression was proposed for predicting the relationship between the effective thermal conductivity and deformation-induced cavities within the present experimental range.

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To develop non-destructive evaluation methods for oxidation damage on graphite components in High Temperature Gas-cooled Reactors (HTGRs), the applicability of ultrasonic wave and micro-indentation methods were investigated. Candidate graphites, IG-110 and IG-430, for core components of Very High Temperature Reactor (VHTR) were used in this study. These graphites were oxidized uniformly by air at 500 0 C. The following results were obtained from this study. (1) Ultrasonic wave velocities with 1 MHz can be expressed empirically by exponential formulas to burn-off, oxidation weight loss. (2) The porous condition of the oxidized graphite could be evaluated with wave propagation analysis with a wave-pore interaction model. It is important to consider the non-uniformity of oxidized porous condition. (3) Micro-indentation method is expected to determine the local oxidation damage. It is necessary to assess the variation of the test data.