MOLTEN SAND INDUCED DEGRADATION OF ULTRA HIGH TEMPERATURE CERAMIC DIBORIDES
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Authors
Vorbroker, Collin L.
Subjects
UHTC
hafnium diboride
HfB2
zirconium diboride
ZrB2
high entropy ceramics
(Ta0.20
Zr0.20
Nb0.20
Hf0.20
Ti0.20)B2
sand intrusion
sand phobic
CMAS
hafnium diboride
HfB2
zirconium diboride
ZrB2
high entropy ceramics
(Ta0.20
Zr0.20
Nb0.20
Hf0.20
Ti0.20)B2
sand intrusion
sand phobic
CMAS
Advisors
Ansell, Troy
Date of Issue
2023-06
Date
Publisher
Monterey, CA; Naval Postgraduate School
Language
Abstract
The desire for increased performance of gas turbine engines (GTE) is leading to higher operational temperatures within GTEs. Thermal and environmental barrier coatings (T/EBC) applied to turbine blades (typically the hottest component) allow for temperatures to reach as high as 1700 °C. T/EBCs; however, they are susceptible to deterioration when in contact with liquified atmospheric particulates. These particulates are composed of varying amounts of calcia, magnesia, alumina, and silicates (CMAS). At elevated GTE operating temperatures, the molten CMAS attacks the T/EBC, greatly reducing the performance and lifespan of turbine blades. The goal of this thesis is to examine how three different ceramic compositions withstand CMAS penetration. The ceramics are hafnium diboride (HfB2), zirconium diboride (ZrB2), and a high entropy ceramic diboride (Ta0.20, Zr0.20, Nb0.20, Hf0.20, Ti0.20)B2. The ceramics were exposed to a 1:1 CMAS water slurry then placed in the furnace at 1300°C and 1600°C for 1 and 10 hours. The samples were then analyzed via scanning electron microscope (SEM) and x-ray diffraction (XRD) to identify CMAS penetration and reaction products. Nano-indentation hardness testing was then performed to evaluate how the CMAS impacted the hardness. All samples experienced CMAS intrusion and oxidation with varying effects on the material’s nano-hardness.
Type
Thesis
Description
Series/Report No
Department
Mechanical and Aerospace Engineering (MAE)
Organization
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Sponsors
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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.