Doctoral Dissertations

Wenbin Li

Keywords and Phrases

Additive manufacturing; Ceramics; Composites; Functionally graded material; Material extrusion; Support material

Abstract

"Ceramic On-Demand Extrusion (CODE) is a recently developed freeform extrusion fabrication process for producing dense ceramic components from single and multiple constituents. In this process, aqueous paste of ceramic particles with a very low binder content ( < 1 vol%) is extruded through a moving nozzle to print each layer sequentially. Once one layer is printed, it is surrounded by oil to prevent undesirable water evaporation from the perimeters of the part. The oil level is regulated just below the topmost layer of the part being fabricated. Infrared radiation is then applied to uniformly and partially dry the top layer so that the yield stress of the paste increases to avoid part deformation. By repeating the above steps, the part is printed in a layer-wise fashion, followed by post-processing. Paste extrusion precision of different extrusion mechanisms was compared and analyzed, with an auger extruder determined to be the most suitable paste extruder for the CODE system. A novel fabrication system was developed based on a motion gantry, auger extruders, and peripheral devices. Sample specimens were then produced from 3 mol% yttria stabilized zirconia using this fabrication system, and their properties, including density, flexural strength, Young's modulus, Weibull modulus, fracture toughness, and hardness were measured. The results indicated that superior mechanical properties were achieved by the CODE process among all the additive manufacturing processes. Further development was made on the CODE process to fabricate ceramic components that have external/internal features such as overhangs by using fugitive support material. Finally, ceramic composites with functionally graded materials (FGMs) were fabricated by the CODE process using a dynamic mixing device"--Abstract, page iv.

Advisor(s)

Leu, M. C. (Ming-Chuan)

Committee Member(s)

Landers, Robert G.
Hilmas, Greg
Liou, Frank W.
Huang, Jie

Department(s)

Mechanical and Aerospace Engineering

Degree Name

Ph. D. in Mechanical Engineering

Sponsor(s)

U.S. National Energy Technology Laboratory
United States. Department of Energy
Honeywell Federal Manufacturing and Techologies, LLC

Comments

The authors gratefully acknowledge the financial support of this research by the National Energy Technology Laboratory of the Department of Energy under the contract No. DE-FE0012272.
This work was funded by Honeywell Federal Manufacturing & Technologies under Contract No. DE-NA0002839 with the U.S. Department of Energy.

Publisher

Missouri University of Science and Technology

Publication Date

Spring 2019

Journal article titles appearing in thesis/dissertation

  • Extrusion-on-demand methods for high solids loading ceramic paste in freeform extrusion fabrication
  • Characterization of zirconia specimens fabricated by ceramic on-demand extrusion
  • Fabricating ceramic components with water dissolvable support structures by the ceramic on-demand extrusion process
  • Fabricating functionally graded materials by ceramic on-demand extrusion with dynamic mixing

Pagination

xiv, 125 pages

Note about bibliography

Includes bibliographic references.

Rights

© 2019 Wenbin Li, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 11538

Electronic OCLC #

1105154902

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