Doctoral Dissertations

Keywords and Phrases

Carbides; Cermets; Mechanical Properties; NTP; Thermal Properties; ZrC

Abstract

This research focuses on the processing and properties of zirconium carbide-based materials to promote their use in extreme environment aerospace applications, including nuclear thermal propulsion and hyper sonics. Several carbide systems including ZrC, ZrC-Mo cermets, (Zr, Nb)C, and a high entropy carbide were developed. The ZrC-Mo cermet was studied extensively to understand the effect of starting carbide grain size on the final microstructure, composition, elastic moduli, hardness, fracture toughness, room and elevated temperature flexural strength, thermal diffusivity, electrical resistivity, thermal expansion coefficient, and thermal conductivity. It was shown that heat transport in the cermets was dominated by the ZrC phase as well as several compositional interactions. Two methods were employed to sinter the ZrC-Mo and (Zr, Nb)C with integral cooling channels using fugitive materials in an effort to reduce required post process machining as the matrix material is a surrogate for fissile fuel. One method involved inserting a Mo loaded thermoplastic rod while the other method consisted of pouring loose powder around graphite pins in an array before densifying. The Mo rod worked best with the cermet composition with limited cracking, while the graphite pins worked with the (Zr, Nb)C due to thermal mismatch leading to radial cracking of the incompatible materials. A carbothermal reduction process was used to synthesize both ZrC and a high entropy carbide in an effort to produce high purity, nominally dense, carbides. After hot pressing, the ZrCx stoichiometry was estimated and the room temperature mechanical properties of the ZrC and HEC were measured to compare both the difference between monocarbides and high entropy systems as well as commercial versus synthesized carbides.

Advisor(s)

Hilmas, Greg

Committee Member(s)

Emdadi, Arezoo
Lonergan, Jason
Watts, Jeremy Lee, 1980-
Chandrashekhara, K.

Department(s)

Materials Science and Engineering

Degree Name

Ph. D. in Ceramic Engineering

Publisher

Missouri University of Science and Technology

Publication Date

Spring 2026

Journal article titles appearing in thesis/dissertation

Paper I, found on pages 35-67, has been published in Ceramics International.

Paper II, found on pages 68-99, is intended for submission to Ceramics International.

Paper III, found on pages 100-135, is intended for submission to International Journal of Applied Ceramic Technology.

Paper IV, found on pages 136-164, is intended for submisstion to Journal of the American Ceramic Society.

Pagination

xiii, 185 pages

Note about bibliography

Includes_bibliographical_references_(pages 171-184)

Rights

© 2026 Nathaniel Hyman Blatt , All Rights Reserved

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 12586

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