Masters Theses

Keywords and Phrases

Elevated temperature flexural strength; Mechanical Properties; Processing; Zirconium carbide

Abstract

“This research focuses on the processing and mechanical properties of zirconium carbide ceramics (ZrCx). The first goal of this project was to densify near stoichiometric (i.e., x as close to 1 as possible) and nominally phase pure ZrCx. The maximum stoichiometry achieved for the ZrCx (C/Zr ratio of 0.92) was measured using gas fusion analysis. Hot pressing was used to obtain dense ZrCx. Archimedes was used to determine the relative density of hot pressed ZrCx at > 95%. Scanning electron microscopy (SEM) was used to determine the overall microstructure of the hot pressed ZrCx. The measured porosity was ~4 vol% and additional unreacted carbon was observed in SEM images. The average grain size was 2.7 ± 1.4 μm with a maximum observed grain size of 17.5 μm. The second goal of the project was to measure the hardness, flexure strength, and fracture toughness of ZrCx at room temperature. Flexure strength at elevated temperatures, from 1600 to 2400°C, was also measured. Vickers’ hardness was measured at two different loads and decreased from 19.5 GPa at a load of 0.5 kgf to 17.0 GPa at a load of 1 kgf. Flexure strength was 362.3 ± 46 MPa at room temperature and was roughly constant up to 2200°C where the strength decreased to 283 ± 34 MPa. Fracture toughness was determined to be 2.9 ± 0.1 MPa·m1/2 at room temperature. A Griffith-type analysis was used in determining the strength limiting flaws in the room temperature tests which was determined to be the largest grains of ZrC in the microstructure. The test bars used in the high temperature tests showed a slight increase in the average grain size but still within the standard deviation of the room temperature test bars”--Abstract, page iv.

Advisor(s)

Hilmas, Greg

Committee Member(s)

Fahrenholtz, William
Watts, Jeremy Lee, 1980-

Department(s)

Materials Science and Engineering

Degree Name

M.S. in Ceramic Engineering

Comments

The author would like to thank NSF for providing the funding for this research with grant number DMR-1742086.

Publisher

Missouri University of Science and Technology

Publication Date

Summer 2020

Journal article titles appearing in thesis/dissertation

  • Processing and Room Temperature Properties of Zirconium Carbide
  • Ultra High Temperature Strength of Zirconium Carbide

Pagination

x, 51 pages

Note about bibliography

Includes bibliographic references.

Rights

© 2020 Nicole Mary Korklan, All rights reserved.

Document Type

Thesis - Open Access

File Type

text

Language

English

Thesis Number

T 11751

Electronic OCLC #

1198499016

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