Processing and Thermal Properties of an Mo₅Si₃C-SiC Ceramic

Abstract

Composite ceramics containing similar 25 vol% of the Mo-Si-C ternary compound and SiC (referred to as MS) were reaction hot pressed up to 96% relative density. The electrical resistivity of the composite processed at 2150 °C decreased from similar4.60 Ω cm at room temperature to 4.15 Ω cm at 700 °C. Thermal conductivity of the MS ceramics processed at 2150 °C was above 100 W/m K at room temperature, decreasing to between 62 and 68 W/m K at 500 °C. Using the Eucken model for thermal conductivity, the interconnected SiC phase in the MS materials was calculated to have a room temperature thermal conductivity between 160 and 170 W/m K. As compared to a baseline SiC composition, the continuous SiC in the MS materials had an average increase in thermal conductivity of similar 50% over the temperature range of room temperature to 500 °C. This increase in thermal conductivity was attributed to the accommodation of impurities that would typically be present in SiC grains and grain boundaries (e.g., N and O) into the ternary phase.

Department(s)

Materials Science and Engineering

Sponsor(s)

Oak Ridge National Laboratory
United States. Department of Energy. Office of Transportation Technologies
United States. Department of Education
United States. Department of Energy
U.S. Army Space and Missile Defense Command

Keywords and Phrases

Diffraction; Electron Microscopy; Molybdenum Silicides; Reaction Synthesis

International Standard Serial Number (ISSN)

0966-9795

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2008 Elsevier, All rights reserved.

Publication Date

01 Jul 2008

Link to Full Text

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