Effects of Neutron Irradiation on Thermal Conductivity of SiC-Based Composites and Monolithic Ceramics

Abstract

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Limits on irradiation-induced thermal conductivity and electrical resistivity in silicon carbide materials

“…3 the density decrease (driven by interstitial defect strain) upon irradiation for this work and that of Price [15] were measured in similar fashion and are in good agreement. However, while the thermal defect resistance data is consistent for this work and the work of Youngblood [17] and Senor [16], the Price [15] data is somewhat higher. Assuming no experimental error, this suggests there may be a difference in the vacancy complex formation for the lower density, lower conductivity material of Price [15].…”

“…It is seen that irradiated saturation thermal conductivity increases from a value of $7 W/m K at 200°C to 20-27 W/m K for 1000°C irradiation. The wide range at the elevated temperature may be due to a non-saturated value of thermal conductivity for the present work and that of Youngblood [17] which was in the dose range of 4-8 dpa as compared to that of Senor [16] taken as $26 dpa. A saturation value closer to 20 W/m K is therefore likely.…”

“…3 gives a compilation of thermal defect resistance for highly irradiated, near fully dense high-purity CVD SiC. Using data from this study, Price [15], Senor [16], and Youngblood [17]. The published data for siliconized and hot pressed materials were omitted due to the presence of sintering aids that potentially alter grain boundary scattering upon irradiation.…”

“…Error bars were calculated based on information provided by the authors, or assumed. Room temperature thermal conductivities (given in legend) of 288 W/m K were assumed [18] for the work of Youngblood [17] and Senor [16].…”

“…3 is the ideal, or maximum saturated thermal conductivity band, as a function of irradiation temperature. This band has simply inverted the thermal defect resistance data from this study as well as the data of Youngblood [17] and Senor [16] (all Morton/RohmHaas CVD SiC). This is therefore the thermal conductivity dominated solely by the irradiation-induced vacancy clusters, and the room temperature thermal conductivity can be assumed to be near the thermal conductivity measured at the irradiation temperature.…”