Virginia Tech
Structure, property, and processing relationships of CMZP - [(Ca<sub>0.6</sub>,Mg<sub>0.4</sub>)Zr₄(PO₄)₆]
Abstract
dc:description.abstractProcessing of (Ca<sub>0.6</sub>, Mg<sub>0.4</sub>)Zr₄(PO₄)₆ [CMZP] powder synthesized by sol-gel techniques was investigated. Amorphous powder was cold pressed/sintered and hot pressed. Cold pressing CMZP, followed by controlled drying and sintering, resulted in maximum relative densities of 96% when using 2wt% of a sintering aid (ZnO). When increasing ZnO content to ≥ 5wt%, a second phase ((ZrO)₂P₂O₇) was formed. Hot pressing conditions were optimized to yield the highest room temperature flexure strength. Mechanical properties of the hot pressed CMZP at room temperature were: (1) a four-point flexure strength of 124.77 MPa, (2) an elastic modulus of 118.45 GPa, and (3) a Weibull modulus of 10.7. At 850°C, the flexure strength and elastic modulus were 118.35 MPa and 68.63 GPa while at 1050°C they were 89.57 MPa and 78.27 GPa. Samples tested at 1250°C creeped during loading. The fracture toughness K<sub>c</sub> of hot pressed CMZP was determined to be 1.145 MPa·√m by indentation. Breaking multiple-indented bars in a four-point bend resulted in a fracture toughness value of 1.269 MPa·√m. The coefficient of thermal expansion (CTE) on heating from 25°C to 1000°C was 2.64 x 10⁻⁶/°C and did not change on cycling ten times to 1000°C. No thermal expansion hysteresis was observed. Elevated temperature X-ray diffraction (XRD) revealed that the hot pressed CMZP remained single phase when heated to 1200°C and cooled to room temperature.
Degree
thesis:*- Name thesis:degree_name
- Master of Science
- Level thesis:degree_level
- masters
- Discipline thesis:degree_discipline
- Materials Science and Engineering
- Department dc:contributor.department
- Materials Science and Engineering
- Grantor dc:publisher
- Virginia Tech
- Year dc:date.issued
- 1994
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Russ, William M.
Rights
dc:rights- Statement dc:rights
-
- In Copyright
- Licence dc:rights.uri
- Language dc:language.iso
- en
Identifiers
dc:identifier.*- Dc Identifier Other
- etd-01172009-063047
- OAI identifier oai:identifier
- oai:vtechworks.lib.vt.edu:10919/40630