Influence of alumina on the structure and mechanical properties of yttria-stabilized zirconia composites. Final report, 10 January 1984-10 January 1985

Technical Report · Mon Jul 22 00:00:00 EDT 1985

OSTI ID:6145817

Buchanan, R C; Davison, W W

Composite structure of yttria (4.5 wt%) stabilized zirconia (YSZ) with added Al/sub 2/O/sub 3/ (0.3-7.5 wt%) were investigated. They show fracture toughness (KIc) and strength (MOR) values in excess of 9.0 MPa X the square root of M and 500 MPa, respectively, more than twice that normally reported for YSZ samples of like composition. Starting materials used were floated Al/sub 2/O/sub 3/ and precipitated YSZ powders (approx. 99.9% purity) of average particle size 0.03 ..mu..m. The powders were washed, dispersed, ball milled, spray dried, dry pressed, and the resultant compacts sintered at 1300 C/8 h. Microstructures obtained were of uniform grain size (0.2-0.4 ..mu..m) with discrete Al/sub 2/O/sub 3/ inclusions, approximately the same size as the YSZ grains, dispersed throughout the composite structure. The strengthening mechanism involved dissipation of strain energy by plastic deformation of the Al2O3 inclusions in the YSZ matrix. Variation in the mechanical properties and structure of the composite as a function of added Al2O3 was correlated with DC conductivity, X-ray diffraction and lattice parameter data. The X-ray data showed splitting of the main peaks indicating a primarily tetragonal phase. Lattice parameter changes with increasing Al2O3 were attributed to direct substitution of Al(3+) for Zr(4+) ions at low Al2O3 (0.325 wt%) content resulting in increased oxygen vacancies, higher conductivity and lower activation energy.

• Research Organization: Illinois Univ., Urbana (USA). Dept. of Ceramic Engineering
• OSTI ID: 6145817
• Report Number(s): AD-A-159994/3/XAB; TR-11
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM OXIDES
METALLURGICAL EFFECTS
COMPOSITE MATERIALS
MECHANICAL PROPERTIES
YTTRIUM OXIDES
ZIRCONIUM OXIDES
ACTIVATION ENERGY
DIRECT CURRENT
ENERGY
GRAIN SIZE
POWDERS
STABILIZATION
ALUMINIUM COMPOUNDS
CHALCOGENIDES
CRYSTAL STRUCTURE
CURRENTS
ELECTRIC CURRENTS
MATERIALS
MICROSTRUCTURE
OXIDES
OXYGEN COMPOUNDS
SIZE
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
ZIRCONIUM COMPOUNDS
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Cermets
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Cermets
& Refractories- Mechanical Properties