K/sub R/-curve behavior in MgO partially-stabilized zirconia

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1988

OSTI ID:6163026

Readey, M J

Coarse-grain MgO partially-stabilized ZrO/sub 2/ (Mg-PSZ) containing tetragonal precipitates exhibits considerable K/sub R/-curve behavior, i.e., increasing crack resistance with crack extension. During K/sub R/-curve determination of commercial PSZ's, several problems were observed with standard testing techniques, necessitating the development of a new sample geometry to obtain straight and stable crack growth. Impurities were found to play an important role in the plateau toughness and strength. High-toughness and high-strength PSZ's typically contain the least amount of impurities. Tetragonal precipitate size is also a critical parameter in resulting toughness and strength, where the optimum in mechanical properties occurs for precipitates just on the verge of transforming. Peak toughness does not coincide with peak strength as K/sub R/-limited, and not necessarily flaw size controlled in PSZ's. Several conclusions stand out as significant: (1) the extremely high toughness in some PSZ's obtains only after a modest annealing at 1000/sup 0/C for only 20 minutes; (2) PSZ's demonstrated a strong fatigue effect; this phenomenon is large enough to affect toughness and strength; and (3) perhaps most significant, the shape of the K/sub R/-curves depends on the specimen geometry.

• Research Organization: Case Western Reserve Univ., Cleveland, OH (USA)
• OSTI ID: 6163026
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360203* -- Ceramics
Cermets
& Refractories-- Mechanical Properties
ALKALINE EARTH METAL COMPOUNDS
CHALCOGENIDES
CRACKS
GEOMETRY
IMPURITIES
MAGNESIUM COMPOUNDS
MAGNESIUM OXIDES
MATHEMATICS
MECHANICAL PROPERTIES
METALLURGICAL EFFECTS
OXIDES
OXYGEN COMPOUNDS
PRECIPITATION
SEPARATION PROCESSES
STABILIZATION
TRANSITION ELEMENT COMPOUNDS
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES