SINTERING OF ADDITIVELY MANUFACTURED HYDROXYAPATITE EMBEDDED WITH BORON NITRIDE NANOTUBES
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Authors
Matalavage, Nathan J.
Subjects
BNNT
boron nitride nanotubes
alumina
hydroxyapatite
additive manufactured ceramics
ceramic sintering
boron nitride nanotubes
alumina
hydroxyapatite
additive manufactured ceramics
ceramic sintering
Advisors
Ansell, Troy
Date of Issue
2023-06
Date
Publisher
Monterey, CA; Naval Postgraduate School
Language
Abstract
As technologies like hypersonics develop, the need for advanced ceramic and composite materials becomes more urgent. These materials must have unique geometries and exceptional materials properties like high melting (or decomposition) temperature, low thermal conductivity, and high thermal shock resistance. In many cases, the only way to achieve the required geometry is by additive manufacturing. Furthermore, ceramic parts often need to be reinforced with nanoparticles to achieve the desired properties. This presents an issue since the high temperature of ceramic post-processing can degrade or even destroy these nanoparticles. This thesis sought to identify a method to sinter a 3D-printed ceramic while keeping the embedded nanoparticles intact. This work focused on hydroxyapatite [Ca10(PO4)6(OH)2] embedded with boron nitride nanotubes (BNNTs). The samples were heat treated in argon using a tube furnace. The temperature and the sintering medium were varied to determine the ideal process. After post-processing, the samples were evaluated using X-ray diffraction, scanning electron microscope analysis, and the Archimedes method. No significant trends in the density were noted throughout testing; however, it was found that samples that were sintered in a boron nitride powder medium displayed intact BNNTs post-sintering. This demonstrated that BNNTs can survive temperatures far above their oxidation point if the environment is carefully controlled.
Type
Thesis
Description
Series/Report No
Department
Mechanical and Aerospace Engineering (MAE)
Organization
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NPS Report Number
Sponsors
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Citation
Distribution Statement
Approved for public release. Distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.