Masters Theses

Abstract

"This research focuses on the development of a zirconium carbide (ZrC) paste for use in material extrusion direct ink write additive manufacturing (AM) followed by the pressure less densification of ZrC and the mechanical and thermal characterization of the resulting ceramics. A highly loaded, aqueous paste was developed using commercial ZrC powder ball milled to ~1 μm. Optimal dispersant, binder, and solids loading were found by rheological characterization. The paste composition consisted of 46-47 vol% ZrC, 43.5 vol% distilled water, 8.1 vol% dispersant, and 1.6 vol% binder. A yield stress of ~8 Pa allowed for shape retention upon removal of shear. Thermogravimetric analysis was employed to build a debinding schedule. A pressure less sintering schedule of 2000°C for 2 hours in He atmosphere produced ZrC greater than 90% density with grains <5 >μm. ZrC test samples were printed, debinded, and sintered. X-ray diffraction confirmed ZrC was the only phase present in printed parts. Four-point flexural testing demonstrated an average strength of 331.3 ± 57.1 MPa with a Young’s modulus of 232.8 ± 13.1 GPa. Vickers microhardness was 13.6 ± 1.0 GPa at a load of 4.91 N and 11.6 ± 0.5 GPa at a load of 9.81 N. Fracture toughness was 2.9 ± 0.2 MPa⋅m1/2. The largest grain was the critical flaw as determined by Griffith analysis. Thermal conductivity generally increased with temperature from 13.4 W/m⋅K at room temperature to 27.1 W/m⋅K at 2000°C. Room temperature electrical resistivity was found to be 122.4 ± 0.5 μΩ⋅cm; the electron contribution to thermal conductivity was 29% and the phonon contribution was 71%. The developed paste and characterized material add a new method of AM to the processing of ZrC" -- Abstract, p. iv

Advisor(s)

Hilmas, Greg

Committee Member(s)

Watts, Jeremy Lee, 1980-
Leu, M. C. (Ming Chuan)

Department(s)

Materials Science and Engineering

Degree Name

M.S. in Ceramic Engineering

Publisher

Missouri University of Science and Technology

Publication Date

Summer 2024

Pagination

xi, 93 pages

Note about bibliography

Includes_bibliographical_references_(pages 50, 73 & 82-91 )

Rights

©2024 Clare Sabata , All Rights Reserved

Document Type

Thesis - Open Access

File Type

text

Language

English

Thesis Number

T 12407

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