Processing 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. / Master of Science
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/40630 |
| Date | 17 January 2009 |
| Creators | Russ, William M. |
| Contributors | Materials Science and Engineering |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis, Text |
| Format | x, 89 leaves, BTD, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | OCLC# 31236934, LD5655.V855_1994.R877.pdf |
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