Mapping the thermal conductivity of SiC/SiC composites

Brethauer, John

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https://hdl.handle.net/2142/97489 Copy

Description

Title

Mapping the thermal conductivity of SiC/SiC composites

Author(s)

Brethauer, John

Issue Date

2017-04-27

Director of Research (if dissertation) or Advisor (if thesis)

Cahill, David G.

Department of Study

Materials Science & Engineerng

Discipline

Materials Science & Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Silicon carbide (SiC)
• Composite
• Thermal conductivity
• Mapping

Abstract

This thesis investigates the uses of time-domain thermoreflectance (TDTR) to map the thermal conductivity of SiC/SiC composites that are being considered for use as replacement materials in current light-water reactors (LWR), and also as materials for use in next generation nuclear reactors. The thermonuclear properties of the SiC/SiC composites can be tuned to particular situations by varying how the composite is formed. To this end, computational methods are used to predict the properties of these composites. However, currently these methods only take into account the thermal properties of the constituent components of the composite prior to being integrated, potentially missing information on how the thermal properties of the components change post-composite-integration. Additionally, they do not take into account the interfacial thermal conductance between the fiber, interphase, and matrix, and the interphase is typically calculated based on the through-plane thermal conductivity of the matrix, if it is calculated at all. This thesis uses TDTR to map Hi-Nicalon Type S fiber, CVI matrix SiC/SiC composites, enabling the measurement additional thermal information than can be obtained by measuring the matrix or fibers of a composite individually. The thermal conductivity of the interphase is also measured. Crystalline 6H and 4H SiC wafers have their thermal conductivity measured using TDTR, and their phases are confirmed through Raman spectroscopy. The effects of irradiation on SiC is investigated by using TDTR mapping to measure the thermal conductivity of a 6H SiC wafer that has been implanted with He ions. Additional uses of TDTR mapping are explored by measuring the thermal conductivity of hybrid superlattice structures, and beam offset measurements are used to measure the in-plane thermal conductivity of a MEMS infrared detector device.

Graduation Semester

2017-05

Type of Resource

text

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http://hdl.handle.net/2142/97489

Copyright and License Information

Copyright 2017 John Brethauer

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