Synthesis of alumina-zirconia powders by sol-gel processing
The object of this investigation is to determine the feasibility of sol-gel processes for preparing powders of phase-stabilized zirconia. Composites of phase-stabilized zirconia and alumina in which fracture toughening is achieved by the tetragonal to monoclinic transition in ZrO/sub 2/ are one of the promising candidate materials for advanced heat engine applications. To achieve superior strength in these composites, structural considerations dictate that the composites be uniform in composition, passes fine-grained microstructures and be highly dense. Sol-gel processes have the potential for the synthesis of powders from which these composites can be fabricated. Yttrium oxide in concentration of 0.5 to 5 mole % (zirconia basis) was used for phase stabilization of zirconia. In the present study particular emphasis was placed on determining the process parameters which control the homogeneity of Y/sub 2/O/sub 3/ in the zirconia phase. The stress required to transform tetragonal ZrO/sub 2/ during fracture is a function of Y/sub 2/O/sub 3/ content. It is well established that gel composition and properties are controlled by the chemistry and processing conditions employed in the individual steps of sol-gel processes. The present study was concerned with the preparation of gel powders of Al/sub 2/O/sub 3/ - (ZrO/sub 2/ . Y/sub 2/O/sub 3/) from precursor aqueous sols containing the codispersed colloidal oxides. Variables studies included: (1) the pH of the sols from which gelation was effected, (2) the rate of gelation, and (3) the method of synthesizing the colloidal oxides for dispersion as sols. 8 refs., 6 figs.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 7046370
- Report Number(s):
- CONF-870254-2; ON: DE87005721
- Resource Relation:
- Conference: 3. international conference on ultrastructure processing of ceramics, glasses, and composites, San Diego, CA, USA, 23 Feb 1987; 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
CHEMICAL PREPARATION
YTTRIUM OXIDES
ZIRCONIUM OXIDES
CERMETS
FEASIBILITY STUDIES
HYDROLYSIS
MICROSTRUCTURE
PH VALUE
PRECIPITATION
SINTERING
SOL-GEL PROCESS
ALUMINIUM COMPOUNDS
CHALCOGENIDES
CHEMICAL REACTIONS
COMPOSITE MATERIALS
CRYSTAL STRUCTURE
DECOMPOSITION
FABRICATION
LYSIS
MATERIALS
OXIDES
OXYGEN COMPOUNDS
SEPARATION PROCESSES
SOLVOLYSIS
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
ZIRCONIUM COMPOUNDS
360201* - Ceramics
Cermets
& Refractories- Preparation & Fabrication
360202 - Ceramics
Cermets
& Refractories- Structure & Phase Studies