Processing of sinterable transformation toughened ceramics for application in ceramic technology for advanced heat engines project: Final report
Three main types of zirconia toughened ceramics (ZTC) were investigated as potential candidates for heat engine applications, i.e. Mg-PSZ (MgO-Partially Stabilized Zirconia), Y-TZP (Y/sub 2/O/sub 3/-Tetragonal Zirconia Polycrystals), and ZTA (Zirconia Toughened Alumina). The powders were prepared either via chemical routes or by melting, rapid solidification, and wet milling. Hot isostatic pressing was used in the exploratory part of this program in order to quickly evaluate the potential of each composition without the necessity of optimizing the powder processing composition (Y-TZP) considerable effort was devoted to minimize foreign contaminants and processing flaws in order to improve the properties and the reliability of the ceramics. The Mg-PSZ ceramics could not be fabricated due to persistent cracking solidified (R/S) powders have met all objectives, except the strength and toughness at 1000/degree/C. We believe that the strength goal of 500 MPa at 1000/degree/C for pressureless sintered Y-TZP ceramics is attainable through improvements in processing, but the K/sub IC/ goal of 6 MPa. m/sup /1/2// at 1000/degree/C is unrealistic, in view of the lack of transformation toughening at high temperature. The ZTA ceramics have exhibited much better strength and toughness retention at high temperature, vis a vis the Y-TZP materials. These ceramics seem to possess the highest potential for meeting the program goals, but much more processing efforts are needed to optimize their microstructure and maximize their properties. Other advantages of the ZTA materials vs. the Y-TZPs are their lower cost and potentially better resistance to low temperature degradation in the 200--300/degree/C range. 29 refs., 36 figs., 21 tabs.
- Research Organization:
- Oak Ridge National Lab., TN (USA); Norton Co., Northboro, MA (USA)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 6743920
- Report Number(s):
- ORNL/Sub-85-22031/1; ON: DE89001313
- Resource Relation:
- Other Information: Portions of this document are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ALUMINIUM OXIDES
FRACTURE PROPERTIES
CERAMICS
CERIUM OXIDES
HAFNIUM OXIDES
YTTRIUM OXIDES
ZIRCONIUM OXIDES
CHEMICAL COMPOSITION
HEAT ENGINES
MICROSTRUCTURE
PHASE TRANSFORMATIONS
POWDERS
PROCESSING
PROGRESS REPORT
SINTERING
SOLIDIFICATION
TEMPERATURE EFFECTS
THERMAL CONDUCTIVITY
THERMAL DIFFUSIVITY
ALUMINIUM COMPOUNDS
CERIUM COMPOUNDS
CHALCOGENIDES
CRYSTAL STRUCTURE
DOCUMENT TYPES
ENGINES
FABRICATION
HAFNIUM COMPOUNDS
MECHANICAL PROPERTIES
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
REFRACTORY METAL COMPOUNDS
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
ZIRCONIUM COMPOUNDS
360203* - Ceramics
Cermets
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360201 - Ceramics
Cermets
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360202 - Ceramics
Cermets
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