University of Illinois Urbana-Champaign

Geopolymer-derived ceramics and composites

Steveson, Andrew Jacob

Content Files
STEVESON-DISSERTATION-2020.pdf

Permalink

https://hdl.handle.net/2142/108009

Description

Title
Geopolymer-derived ceramics and composites
Author(s)
Steveson, Andrew Jacob
Issue Date
2020-05-08
Director of Research (if dissertation) or Advisor (if thesis)
Kriven, Waltraud M
Doctoral Committee Chair(s)
Kriven, Waltraud M
Committee Member(s)
  • Bass, Jay D
  • Lange, David A
  • Krogstad, Jessica A
  • Maass, C. Robert E
Department of Study
Materials Science & Engineerng
Discipline
Materials Science & Engr
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Date of Ingest
2020-08-26T21:54:58Z
Keyword(s)
  • geopolymers
  • tailorable thermal expansion
  • ceramics
  • composites
  • environmental barrier coatings (EBC)
  • thermal barrier coatings (TBC)
Abstract
The development of ceramics and composites from geopolymer precursors is leading to exciting new avenues in ceramic synthesis and composite applications. In this work, we developed, synthesized, and characterized materials derived from geopolymers for use in extreme environments. In the first section, a method of engineering tectosilicate material systems with tailorable thermal expansion was developed with the goal of designing new candidate materials for environmental barrier applications. The materials were studied with in situ high temperature synchrotron X-ray diffraction to explore the atomic mechanisms responsible for the thermal evolution of these compounds. The framework distortions identified were then systematically manipulated to give tailored thermal expansion values. Several material candidates were identified for environmental barrier coating applications. Rule of mixtures models were used to predict unit cell volumes and thermal expansion coefficients for compounds of intermediate composition. The error in such predictions did not exceed 0.19% (4.98 Å3) in unit cell volume and 0.132 10-5/°C (9.13%) in thermal expansion coefficients. In the second section, geopolymer matrix composites were developed to improve the toughness over unreinforced geopolymers. The ultimate flexure strengths in 3-point bending of fiber-reinforced and minibar-reinforced composite systems were 20% and 59% higher than that of the pure potassium geopolymer, respectively; ultimate compressive strengths were 41% and 36% lower; and fracture toughness was 936% and 4243% higher, as measured by the single-edge notched beam method.
Graduation Semester
2020-05
Type of Resource
Thesis
Permalink
http://hdl.handle.net/2142/108009
Copyright and License Information
Copyright 2020 Andrew Steveson

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Graduate Theses and Dissertations at Illinois
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