Low-temperature aging of t prime -zirconia; The role of microstructure on phase stability
- Utah Univ., Salt Lake City, UT (United States). Dept. of Materials Science and Engineering
This paper reports on polycrystalline, tetragonal (t{prime}) zirconia samples containing 3 and 4 mol% yttria that were fabricated by annealing pressureless-sintered samples in air at {approximately} 2100{degrees} C for 15 min. The grain size of these fully tetragonal samples was on the order of 100 to 200 {mu}m. Domain structure of the samples and of a 3-mol%-yttria-doped tetragonal zirconia single crystal was examined by transmission optical microscopy under polarized light and by transmission electron microscopy. The orientations of the domain/colony boundaries were in accord with the predictions of group theory. As-polished surfaces of polycrystalline t{prime} materials showed no monoclinic phase even after 1000 h at 275{degrees} C in air. By contrast, conventionally yttria-doped tetragonal zirconia polycrystalline (Y-TZP) ceramics of grain size {gt}0.5 {mu}m showed substantial transformation. Surface grinding enhanced the resistance to degradation of Y-TZP but decreased that of t{prime} materials. Even then, the t{prime} materials exhibited better resistance to degradation than the Y-TZP ceramics. Excellent resistance of the t{prime} materials to low-temperature aging despite a very large grain size and the opposite effect of grinding on phase stability are all explained on the basis of ferroelastic domain structure of these materials.
- OSTI ID:
- 5835055
- Journal Information:
- Journal of the American Ceramic Society; (United States), Vol. 74:8; ISSN 0002-7820
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ZIRCONIUM OXIDES
AGING
MICROSTRUCTURE
OPTICAL PROPERTIES
STABILITY
YTTRIUM ADDITIONS
DOMAIN STRUCTURE
FABRICATION
GRAIN BOUNDARIES
PHASE TRANSFORMATIONS
POLARIZED BEAMS
POLYCRYSTALS
SINTERING
STABILIZED SUPERCONDUCTORS
TETRAGONAL LATTICES
TRANSMISSION ELECTRON MICROSCOPY
ALLOYS
BEAMS
CHALCOGENIDES
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CRYSTALS
ELECTRON MICROSCOPY
MICROSCOPY
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SUPERCONDUCTORS
TRANSITION ELEMENT COMPOUNDS
YTTRIUM ALLOYS
ZIRCONIUM COMPOUNDS
360202* - Ceramics
Cermets
& Refractories- Structure & Phase Studies