Cyclic fatigue-crack propagation in ceramics: Behavior in overaged and partially-stabilized MgO-zirconia

Conference · Wed Jun 01 04:00:00 EDT 1988

OSTI ID:5372418

Dauskardt, R. H.; Marshall, D. B.; Ritchie, R. O. ^[1]

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1. Lawrence Berkeley Lab., CA (USA)

The growth of fatigue cracks under (tension-tension) cyclic loading is unequivocally demonstrated for ceramic materials, based on experiments using compact-tension specimens of a MgO partially-stabilized zirconia (PSZ), heat treated to vary the fracture toughness K{sub c} from {approximately}3 MPa{radical}m (overaged condition) to 16 MPa{radical}m (peak-toughness condition) and tested in inert and moist environments. Analogous to behavior in metals, cyclic fatigue-crack growth rates (over the range 10{sup {minus}11} to 10{sup {minus}5} m/cycle) are found to be a function of the stress-intensity range, environment, fracture toughness and load ratio, and to show evidence of crack closure. Similarly under variable-amplitude cyclic loading conditions, crack-growth rates show transient accelerations following low-high block overloads and transient retardations following high-low block overloads or single tensile overloads, again analogous to behavior commonly observed in ductile meals. Cyclic crack-growth rates are observed at stress intensities as low as 50% of K{sub c}, and are typically some 7 orders of magnitude faster than corresponding stress-corrosion crack-growth rates under sustained-loading conditions. 23 refs., 6 figs.

• Research Organization: Lawrence Berkeley Lab., CA (USA)
• Sponsoring Organization: DOE/ER
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 5372418
• Report Number(s): LBL-25457; CONF-880529--9; ON: DE90004247
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360203* -- Ceramics
Cermets
& Refractories-- Mechanical Properties
ALKALINE EARTH METAL COMPOUNDS
CHALCOGENIDES
CHEMICAL REACTIONS
CORROSION
CRACK PROPAGATION
FATIGUE
FRACTURE MECHANICS
FRACTURE PROPERTIES
HEAT TREATMENTS
MAGNESIUM COMPOUNDS
MAGNESIUM OXIDES
MECHANICAL PROPERTIES
MECHANICS
OXIDES
OXYGEN COMPOUNDS
STRESS CORROSION
TENSILE PROPERTIES
TRANSITION ELEMENT COMPOUNDS
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES