Masters Theses

Keywords and Phrases

ion irradiation; radiation effects; ultra-high temperature ceramics; Zirconium diboride

Abstract

A primary challenge in finding suitable materials for Molten Salt Reactors (MSRs) lies in identifying those that concurrently exhibit high corrosion resistance, stability at elevated temperatures, resistance to radiation, and chemical compatibility with molten salts. 11B-enriched zirconium diboride (ZrB2) is a potential candidate for applications in MSRs due to its unique combination of properties, including high melting point, high thermal conductivity, and resistance to corrosion in harsh environments. This ultra-high temperature ceramic (UHTC) has exhibited stability under extreme conditions, making it an attractive material for components within MSRs.

The microstructural response of ZrB2 under heavy ion irradiation has been characterized. Ceramic samples were prepared via powder processing and irradiated with 5-10 MeV Au ions at room and high temperature (570 ◦C) to doses from 1-8 dpa. The influence of the temperature and damage level on the microstructure was investigated using Grazing Incident X-ray diffraction (GIXRD), Transmission Electron Microscopy (TEM), and Positron Annihilation Lifetime Spectroscopy (PALS). Rietveld analysis of the GIXRD data reveals an accumulation of microstrain at low dpa and room temperature. Dislocations observed in TEM cross-sections are likely the main contributor to the microstrain. High dpa and high-temperature samples exhibit lower lattice distortion than lower dpa samples, suggesting the presence of enhanced defect recovery at elevated temperatures and dislocation annihilation at higher doses. PALS analysis showed no evidence of void growth. Particle-Induced X-Ray Emission (PIXE) and Neutron Activation Analysis (NAA) of the ZrB2 samples showed no significant contamination within manufactured samples. NAA of chloride eutectic salts used in static corrosion testing of the irradiated ZrB2 showed a small amount of Zr present, in addition to potential salt contaminants.

Advisor(s)

Graham, Joseph T.

Committee Member(s)

Lonergan, Jason
Newkirk, Joseph William

Department(s)

Nuclear Engineering and Radiation Science

Degree Name

M.S. in Nuclear Engineering

Publisher

Missouri University of Science and Technology

Publication Date

Summer 2025

Journal article titles appearing in thesis/dissertation

Paper: Pages 22-39 are intended for submission to the Journal of the European Ceramic Society.

Pagination

xi, 66 pages

Note about bibliography

Includes_bibliographical_references_(pages 60-65)

Rights

© 2025 Narrie Loftus , All Rights Reserved

Document Type

Thesis - Open Access

File Type

text

Language

English

Thesis Number

T 12512

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