Influence of Grain Size on Thermal Conductivity of SiC Ceramics

Lee, Young-Ju; Park, Yi-Hyun; Hinoki, Tatsuya

doi:10.1088/1757-899x/18/16/162014

Cited by 16 publications

(8 citation statements)

References 9 publications

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“…It clearly appears that the CDD size increase arises at temperatures below the threshold temperature for defects annealing. This evolution is consistent with the grain size increase observed in nanometric SiC during high‐temperature sintering, where a maximum CDD size close to 70 nm was found . In addition, the threshold for residual microstrains and anisotropy parameter decrease corresponds to a CDD size around 40 nm in agreement with Gubicza et al …”

Section: Resultssupporting

confidence: 91%

“…This evolution is consistent with the grain size increase observed in nanometric SiC during high-temperature sintering, where a maximum CDD size close to 70 nm was found. 23 In addition, the threshold for residual microstrains and anisotropy parameter decrease corresponds to a CDD size around 40 nm in agreement with Gubicza et al 20 The results were compared with TEM observations of asreceived and heat-treated fibers. The observations are summarized in Figs.…”

Section: (3) Microstructural Evolution During Heat Treatmentssupporting

confidence: 79%

“…). A parabolic kinetic law was found which is similar to the classical grain growth processes occurring by coalescence of adjacent grains: Complementary measurements (isothermal annealing) would be required to determine the activation energy of this process.…”

Section: Resultsmentioning

confidence: 74%

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X‐ray Diffraction Study of the Effect of High‐Temperature Heat Treatment on the Microstructural Stability of Third‐Generation SiC Fibers

et al. 2013

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Third‐generation SiC fibers [High Nicalon S (HNS) and Tyranno SA3 (Ty–SA3)] were studied by X‐ray diffraction and transmission electron microscopy (TEM) after heat treatments in neutral atmosphere up to 1900°C. The microstructural changes in both materials were determined using a modified Hall–Williamson method introducing an anisotropy parameter taking into account the high density of planar defects. HNS fibers exhibit significant modifications in the coherent diffraction domains (CDD) size, which drastically increases from 24 to 70 nm in the range 1600°C–1900°C. TEM observations support these results. The residual microstrain values decrease from 0.0015 to 0.0005 between 1750°C and 1850°C. Similarly, the anisotropy parameter significantly decreases in the same temperature range. Concerning the Ty–SA3 fibers, no evolution in terms of CDD size and residual microstrain was observed. However, the anisotropy parameter decreases at 1800°C. TEM observations did not show noticeable grain growth. The grain size was found to be larger than the CDD and the planar defects density to decrease at high temperature. In both types of fibers, the CDD sizes are similar for the highest temperature heat treatments.

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Section: Resultssupporting

confidence: 91%

Section: (3) Microstructural Evolution During Heat Treatmentssupporting

confidence: 79%

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X‐ray Diffraction Study of the Effect of High‐Temperature Heat Treatment on the Microstructural Stability of Third‐Generation SiC Fibers

et al. 2013

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“…7, NITE-SiC exhibits high thermal conductivity in the unirradiated state and, depending on the processing conditions and the resulting microstructure (i.e. grain size [29] and oxide distribution), larger and smaller thermal conductivities have been observed in the past. These thermal conductivity values are shown in Fig.…”

Section: Thermal Conductivitymentioning

confidence: 99%

Progress on matrix SiC processing and properties for fully ceramic microencapsulated fuel form

Terrani

Kiggans

Silva

et al. 2015

Journal of Nuclear Materials

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a b s t r a c tThe consolidation mechanism and resulting properties of the silicon carbide (SiC) matrix of fully ceramic microencapsulated (FCM) fuel form are discussed. The matrix is produced via the nano-infiltration transient eutectic-forming (NITE) process. Coefficient of thermal expansion, thermal conductivity, and strength characteristics of this SiC matrix have been characterized in the unirradiated state. An ad hoc methodology for estimation of thermal conductivity of the neutron-irradiated NITE-SiC matrix is also provided to aid fuel performance modeling efforts specific to this concept. Finally, specific processing methods developed for production of an optimal and reliable fuel form using this process are summarized. These various sections collectively report the progress made to date on production of optimal FCM fuel form to enable its application in light water and advanced reactors.

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“…Therefore, the thermal conductivity was expected to be higher, which was definitely the case. This thesis has been supported by numerous studies on different materials [ 49 , 50 , 51 , 52 ].…”

Section: Resultsmentioning

confidence: 81%

Investigation of Heater Structures for Thermal Conductivity Measurements of SiO2 and Al2O3 Thin Films Using the 3-Omega Method

et al. 2022

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A well-known method for measuring thermal conductivity is the 3-Omega (3ω) method. A prerequisite for it is the deposition of a metal heater on top of the sample surface. The known design rules for the heater geometry, however, are not yet sufficient. In this work, heaters with different lengths and widths within the known restrictions were investigated. The measurements were carried out on SiO2 thin films with different film thicknesses as a reference. There was a significant difference between theoretical deposited heater width and real heater width, which could lead to errors of up to 50% for the determined thermal conductivity. Heaters with lengths between 11 and 13 mm and widths of 6.5 µm or more proved to deliver the most trustworthy results. To verify the performance of these newfound heaters, additional investigations on Al2O3 thin films were carried out, proving our conclusions to be correct and delivering thermal conductivity values of 0.81 Wm−1 K−1 and 0.93 Wm−1 K−1 for unannealed and annealed samples, respectively. Furthermore, the effect of annealing on Al2O3 was studied, revealing a significant shrinking in film thickness of approximately 11% and an increase in thermal conductivity of 15%. The presented results on well-defined geometries will help to produce optimized heater structures for the 3ω method.

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Influence of Grain Size on Thermal Conductivity of SiC Ceramics

Cited by 16 publications

References 9 publications

X‐ray Diffraction Study of the Effect of High‐Temperature Heat Treatment on the Microstructural Stability of Third‐Generation SiC Fibers

X‐ray Diffraction Study of the Effect of High‐Temperature Heat Treatment on the Microstructural Stability of Third‐Generation SiC Fibers

Progress on matrix SiC processing and properties for fully ceramic microencapsulated fuel form

Investigation of Heater Structures for Thermal Conductivity Measurements of SiO2 and Al2O3 Thin Films Using the 3-Omega Method

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