Masters Theses

Alternative Title

Modeling and measurement of thermal residual stresses and isotope effects on thermo physical properties of ZrB2-SiC ceramics

Keywords and Phrases

Zirconium diboride

Abstract

"Commercially available finite element modeling software (ABAQUS) was used to investigate the internal residual stresses that develop as a result of cooling from processing temperatures in ZrB₂-SiC ceramics. The size and shape of the SiC particles were varied to evaluate their effect on the residual stresses. Results were compared to experimental data and showed similar trends, where increasing SiC particle size increased tensile stress and also decreased strength. Models were used to analyze benefits of novel shaped SiC inclusions and also better understand the short comings of the composites. An attempt to validate the models using neutron diffraction to measure residual stress led to the fabrication of ZrB₂-SiC composites made using isotopically pure ¹¹B and a reaction hot pressing technique. Natural boron in conventional ZrB₂ ceramics had to be replaced with the ¹¹B (0.0055 barns) due to the high thermal neutron absorption of natural boron (767 barns). Neutron diffraction experiments were successfully performed at Argonne National Laboratory, however, stress free reference samples for ZrB₂ and SiC must still be measured to complete the residual stress analysis. ZrB₂-SiC ceramics made from ¹¹B were characterized to confirm a complete reaction and full density. The microstructure was compared to natural B ZrB₂-SiC ceramics to confirm equivalent grain size. Effects on the thermal properties by the ¹¹B isotope were studied by measuring thermal diffusivity of both natural boron and ¹¹B containing ZrB₂-SiC specimens at Oak Ridge National Laboratory. The thermal conductivity and thermal expansion were both determined to be lower for the ¹¹B containing materials--Abstract, page iv.

Advisor(s)

Hilmas, Greg

Committee Member(s)

Chandrashekhara, K.
Fahrenholtz, William

Department(s)

Materials Science and Engineering

Degree Name

M.S. in Materials Science and Engineering

Publisher

Missouri University of Science and Technology

Publication Date

Summer 2008

Journal article titles appearing in thesis/dissertation

  • Finite element modeling of internal stress factors for ZrBâ -SiC ceramics
  • Finite element modeling of internal stress factors for ZrB2-SiC ceramics
  • Processing and thermal properties of ZrB₂-SiC ceramics made with isotopically pure ¹¹Boron
  • Processing and thermal properties of ZrB2-SiC ceramics made with isotopically pure 11Boron

Pagination

xi, 111 pages

Rights

© 2008 Michael Phillip Teague, All rights reserved.

Document Type

Thesis - Open Access

File Type

text

Language

English

Library of Congress Subject Headings

Borides -- Thermal properties
Heat resistant materials
Residual stresses
Silicon carbide -- Thermal properties
Zirconium -- Thermal properties

Thesis Number

T 9418

Print OCLC #

276937415

Electronic OCLC #

244485228

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