Yttria stabilized zirconia (YSZ) is a polymorph with possible phase transformation toughening occurring during impact. The fractography and mechanical properties of laminated alumina and YSZ were studied in this thesis. Five sample types were studied in this thesis: (5:5) Al2O3/YSZ (a sequence of 5 alumina tapes stacked on 5 YSZ tapes), (5:5) Al2O3/YSZ (1 wt.% Pure ZrO2), (7:3) Al2O3/YSZ, Al2O3, and YSZ. Scanning electron microscopy (SEM) and X-ray microscopy (XRM) were used to study morphology and crack propagation with three-point tests performed to study the flexural strength. X-ray diffraction (XRD) spectra of all samples pre and post three-point tests were examined to determine if a change in monoclinic zirconia occurred. The combination of SEM and XRM data found microcracks in the YSZ layers of Al2O3/YSZ laminates with none present on YSZ laminates, leading to the conclusion tensile stress was performed on YSZ during sintering with Al2O3. Fracture patterns show a curving of cracks in Al2O3 layers and abrupt, jagged breaks in YSZ layers with crack forking at major YSZ microcrack regions. YSZ laminates were found to have the highest average flexural strength, but a very high standard deviation and low sample count and Al2O3 laminates having the second highest flexural strength. The (7:3) Al2O3/YSZ laminates had a significant increase in flexural strength compared to both types of (5:5) Al2O3/YSZ laminates. Significant change in monoclinic presence was not found except for the (5:5) Al2O3/YSZ (1 wt.% Pure ZrO2) laminates.
| Identifer | oai:union.ndltd.org:unt.edu/info:ark/67531/metadc1873642 |
| Date | 12 1900 |
| Creators | Cotton, Shomari Johnny |
| Contributors | Reidy, Richard, Scharf, Thomas, Aouadi, Samir |
| Publisher | University of North Texas |
| Source Sets | University of North Texas |
| Language | English |
| Detected Language | English |
| Type | Thesis or Dissertation |
| Format | x, 52 pages, Text |
| Rights | Public, Cotton, Shomari Johnny, Copyright, Copyright is held by the author, unless otherwise noted. All rights Reserved. |
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