Thermal conductivity degradation induced by point defects in irradiated silicon carbide

2011 ◽  
Vol 98 (19) ◽  
pp. 191905 ◽  
Author(s):  
Jean-Paul Crocombette ◽  
Laurent Proville
Keyword(s):  
Thermal Conductivity ◽  
Silicon Carbide ◽  
Point Defects

Effects of rare-earth oxide and alumina additives on thermal conductivity of liquid-phase-sintered silicon carbide

2003 ◽  
Vol 18 (8) ◽  
pp. 1854-1862 ◽  
Author(s):  
You Zhou ◽  
Kiyoshi Hirao ◽  
Yukihiko Yamauchi ◽  
Shuzo Kanzaki
Keyword(s):  
Thermal Conductivity ◽  
Silicon Carbide ◽  
Rare Earth ◽  
Liquid Phase ◽  
Point Defects ◽  
Rare Earth Oxide ◽  
Low Oxygen ◽  
Sic Ceramics ◽  
Sintered Silicon ◽  
Thermal Conductivities

SiC ceramics were prepared from a β–SiC powder doped with two different sintering additives—a mixture of La2O3and Y2O3and a mixture of Al2O3and Y2O3—by hot pressing and annealing. Their microstructures, phase compositions, lattice oxygen contents, and thermal conductivities were evaluated. The SiC doped with rare-earth oxides attained thermal conductivities in excess of 200 W/(m K); however, the SiC doped with additives containing alumina had thermal conductivities lower than 71 W/(m K). The high thermal conductivity of the rare-earth-oxide-doped SiC was attributed to the low oxygen content in SiC lattice, high SiC–SiC contiguity, and lack of β– to α–SiC polytypic transformation. The low thermal conductivity of the alumina-doped SiC was attributed to the point defects resulting from the dissolution of Al2O3into SiC lattice and the occurrence of polytypic transformation.

Atomistic Simulation Studies of the Effects of Defects on Thermal Properties of Ultra High Temperature Ceramics

2016 ◽  
Author(s):  
S. N. Medyanik ◽  
N. Vlahopoulos
Keyword(s):  
Thermal Conductivity ◽  
Silicon Carbide ◽  
Thermal Properties ◽  
High Temperature ◽  
Point Defects ◽  
Atomistic Simulation ◽  
Atomistic Simulations ◽  
Hypersonic Vehicles ◽  
Simulation Studies ◽  
Ultra High Temperature Ceramics

Due to the harsh environments created by high speeds, significant new demands are placed on materials used for constructing hypersonic vehicles. Ultra high temperature ceramics (UHTCs) like carbides and borides exhibit unique thermal properties, such as very high melting points and good thermal conductivities. These properties make the ceramic materials good candidates for applications like Thermal Protection Systems (TPS) of the hypersonic vehicles. However, thermal properties of UHTCs may be very sensitive to microstructures of the materials. Thus, atomic scale defects may impact certain thermal properties, such as thermal conductivity. The effects of such small defects may be properly studied only through atomistic simulation methods, such as molecular dynamics (MD). Previously, atomistic simulation studies have been performed for the effects of point defects on thermal properties in silicon carbide (SiC). In addition, atomistic simulations have been applied to assess thermal conductivity in zirconium diboride (ZrB2) for perfect crystals and polycrystals. However, to our knowledge, no studies of the effects of point defects have been performed for zirconium diboride. This paper applies atomistic simulations to assess the impact of point defects on thermal conductivity in ZrB2 perfect crystals. Recently derived interatomic potential for ZrB2 along with LAMMPS molecular simulation package and MedeA software environment are employed in this effort. Phonon part of the thermal conductivity is calculated using Green-Kubo method. Calculations for a perfect crystal are conducted first and the results are compared to experimental data available from the literature. Then, several types of point defects are considered (vacancies, substitutions, and interstitials) and their impact on the phonon conductivity is evaluated. It is found that even a small concentration of point defects may have substantial effect and result in a reduction in the thermal conductivity values by almost an order of magnitude. The obtained results are in good qualitative agreement with previous studies conducted for silicon carbide. The methodology which is utilized in this work, the modeling procedure, and the obtained results are discussed in this paper.

High thermal conductivity of pure dense SiC ceramics prepared via HTPVT

2019 ◽  
Vol 12 (03) ◽  
pp. 1950032 ◽  
Author(s):  
Yuchen Deng ◽  
Yaming Zhang ◽  
Nanlong Zhang ◽  
Qiang Zhi ◽  
Bo Wang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Silicon Carbide ◽  
Grain Size ◽  
Phase Composition ◽  
Room Temperature ◽  
Vapor Transport ◽  
Physical Vapor Transport ◽  
Growth Substrate ◽  
Sic Ceramics ◽  
Evolution Of Microstructure

Pure dense silicon carbide (SiC) ceramics were obtained via the high-temperature physical vapor transport (HTPVT) method using graphite paper as the growth substrate. The phase composition, the evolution of microstructure, the thermal diffusivity and thermal conductivity at RT to 200∘C were investigated. The obtained samples had a relative density of higher than 98.7% and a large grain size of 1[Formula: see text]mm, the samples also had a room-temperature thermal conductivity of [Formula: see text] and with the temperature increased to 200∘C, the thermal conductivity still maintained at [Formula: see text].

A Study of Oxide Etch Angle of Edge Termination Field Plate for Fabrication of SiC SBD

2017 ◽  
Vol 730 ◽  
pp. 102-105
Author(s):  
Ey Goo Kang
Keyword(s):  
Thermal Conductivity ◽  
Silicon Carbide ◽  
Breakdown Voltage ◽  
Dielectric Breakdown ◽  
Power Semiconductor ◽  
Field Plate ◽  
Edge Termination ◽  
Power Semiconductor Devices ◽  
Silicon Materials ◽  
Generation Power

The silicon carbide (SiC) material is being spotlighted as a next-generation power semiconductor material due to the characteristic limitations of the existing silicon materials. SiC has a wider band gap, higher breakdown voltage, higher thermal conductivity, and higher saturation electron mobility than Si. However, actual SiC SBDs exhibit a lower dielectric breakdown voltage than the theoretical breakdown voltage that causes the electric field concentration, a phenomenon that occurs on the edge of the contact surface as in the conventional power semiconductor devices. In this paper, we designed an edge termination structure using a field plate structure through oxide etch angle control, and optimized the structure to obtain a high breakdown voltage. The experiment results indicated that oxide etch angle was 45° when the breakdown voltage characteristics of the SiC SBD were optimized and a breakdown voltage of 681V was obtained.

Enhanced thermal conductivity for polyimide composites with a three-dimensional silicon carbide nanowire@graphene sheets filler

2015 ◽  
Vol 3 (9) ◽  
pp. 4884-4891 ◽  
Author(s):  
Wen Dai ◽  
Jinhong Yu ◽  
Yi Wang ◽  
Yingze Song ◽  
Fakhr E. Alam ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Silicon Carbide ◽  
Three Dimensional ◽  
Graphene Sheets ◽  
Polyimide Composites ◽  
Polyimide Matrix ◽  
Enhanced Thermal Conductivity

3DSG incorporated into a polyimide matrix greatly enhanced its thermal conductivity (up to 2.63 W m−1 K−1), approximately a 10-fold enhancement in comparison with that of neat polyimide.

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