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.
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Doctor of Philosophy (Ph.D.)
College of Engineering and Computer Science
Mechanical and Aerospace Engineering
Length of Campus-only Access
Doctoral Dissertation (Open Access)
Carrasco-Pena, Alejandro, "Mechanical Properties of Brittle Ceramics: Case Study of Boron Rich Ceramics and Acropora cervicornis Coral Skeleton" (2019). Electronic Theses and Dissertations. 6337.