Masters Theses

Keywords and Phrases

Additive Manufacturing; Boron Carbide; Freeze-form Extrusion Fabrication

Abstract

"Boron carbide is a safe, alternative to beryllium as a material for aerospace structures since it is also light-weight and exhibits high strength. This paper discusses a study of the Freeze-form Extrusion Fabrication (FEF) process to fabricate parts from boron carbide. Process parameters and hardware were modified to fabricate boron carbide specimens free of printed defects. Four-point bending tests were performed to measure the flexural strength of fabricated specimens. Observations of the presence of voids caused by ice crystals in fabricated parts led to further development and characterization of the boron carbide paste used with the FEF process. Additives were selected and tested to observe their effect on the size of the ice-crystal voids. Scanning electron microscopy was used to observe the voids left from the ice crystals after part sintering. Post-image analysis was performed to measure approximate sizes of ice-crystal voids and these results were summed up in a void size distribution. Glycerol in a concentration of 25 wt% by water increased the flexural strength of test bars from 58.1 MPa to 67.4 MPa and the sintered relative density from 76.2% to 85.0%. The standard deviation of the flexural strength decreased from 23.0 to 14.5 MPa. None of the additives considered reduced the sizes of the ice crystal voids desirably as the highest relative density of the sintered test bars achieved was only 85.0%."--Abstract, page iii.

Advisor(s)

Leu, M. C. (Ming-Chuan)
Landers, Robert G.

Committee Member(s)

Hilmas, Greg

Department(s)

Mechanical and Aerospace Engineering

Degree Name

M.S. in Mechanical Engineering

Publisher

Missouri University of Science and Technology

Publication Date

Summer 2015

Pagination

ix, 81 pages

Note about bibliography

Includes bibliographical references (pages 78-80).

Rights

© 2015 Aaron Scott Thornton, All rights reserved.

Document Type

Thesis - Open Access

File Type

text

Language

English

Subject Headings

Ceramic materials -- ExtrusionSolid freeform fabricationManufacturing processes

Thesis Number

T 10744

Electronic OCLC #

921186546

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