Abstract

Ceramics are ubiquitous in man-made and natural structures. Their mechanical properties highly depend on their composition, microstructure and level of defects in the bulk of the material, the latter affecting the integrity of the components; such is the case of boron-rich ceramics where large agglomerates create high stressed regions, or coral skeleton where porosity determines their strength against hydrodynamic forces present in the ocean tides. Therefore, studying the properties of ceramic materials using invasive and non-invasive methods helps in the understanding of the link between the properties and the performance of the structures. The aim of this research was to test the novel ceramic component ZrB2-30wt%SiB6 and Acropora cervicornis coral skeleton using non-conventional techniques that allow for the study of their mechanical properties and their behavior when exposed to external loads present in their environments of application. The first part of this study focuses on understanding the effects of adding SiB6 to enhance the mechanical properties of ZrB2 ceramics for their ultra-high temperature use. The second part will emphasize in the behavior of Acropora cervicornis coral skeleton when exposed to compressive forces and the effects porosity has on this structure when subjected to such loads. It was found that the SiB6 phase was not stable after sintering of the composite and large agglomerates were present in the surface of the material acting as stress concentrators, thus compromising the biaxial strength of the component that resulted to be 224.9 MPa. It was also found that coral skeletons are highly susceptible to porosity which creates variability on the elastic modulus ranging from 60-1 GPa for simulated porosity of 0-90% respectively and a strength of 3.56 ± 0.31 GPa obtained through Vickers indentation. Finite element models were developed and validated against experimental results for the ZrB2- 30wt%SiB6 and Acropora cervicornis coral skeleton.

Notes

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Graduation Date

2019

Semester

Spring

Advisor

Kwok, Kawai

Degree

Doctor of Philosophy (Ph.D.)

College

College of Engineering and Computer Science

Department

Mechanical and Aerospace Engineering

Degree Program

Mechanical Engineering

Format

application/pdf

Identifier

CFE0007440

URL

http://purl.fcla.edu/fcla/etd/CFE0007440

Language

English

Release Date

May 2019

Length of Campus-only Access

None

Access Status

Doctoral Dissertation (Open Access)

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