Fracture toughness of MgCr/sub 2/O/sub 4/-based refractory composites

Conference · Tue Nov 01 00:00:00 EST 1988

OSTI ID:6436828

Singh, J P; Poeppel, R B

The effects of unstabilized ZrO/sub 2/ and W inclusions on the fracture surface energy and thermal-shock resistance of MgCr/sub 2/O/sub 4/ have been characterized. The fracture surface energy increased with increasing ZrO/sub 2/ content and decreased as the ZrO/sub 2/ content increased further. The increase in fracture surface energy for MgCr/sub 2/O/sub 4/ /minus/ W with increasing W content was monotonic for the range of composition studied (less than or equal to10.3 vol % W). It is proposed that these fourfold increases in fracture surface energy result from the absorption of energy due to microcrack formation in the MgCr/sub 2/O/sub 4/ matrix, which results from the tensile stresses due to the mismatch in thermal expansion coefficient and/or elastic modulus between the matrix and inclusions. In addition, for MgCr/sub 2/O/sub 4/ /minus/ ZrO/sub 2/ composites, a major cause of microcracking is the tetragonal ..-->.. monoclinic phase transformation of ZrO/sub 2/ and the associated volume expansion. Thermal quench experiments indicated substantial improvements in the thermal-shock resistance of MgCr/sub 2/O/sub 4/ with appropriate ZrO/sub 2/ and W additions. 32 refs., 9 figs., 3 tabs.

• Research Organization: Argonne National Lab., IL (USA). Materials and Components Technology Div.
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 6436828
• Report Number(s): CONF-881207-3; ON: DE89009847
• Resource Relation: Conference: 7. international symposium on ceramics, Bologna, Italy, 14 Dec 1988; Other Information: Portions of this document are illegible in microfiche products
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
36 MATERIALS SCIENCE
CHROMIUM OXIDES
FRACTURE PROPERTIES
MAGNESIUM OXIDES
TUNGSTEN
ZIRCONIUM OXIDES
COMPOSITE MATERIALS
FLEXURAL STRENGTH
INCLUSIONS
MICROSTRUCTURE
PHASE TRANSFORMATIONS
SURFACE ENERGY
SURFACE PROPERTIES
THERMAL SHOCK
ALKALINE EARTH METAL COMPOUNDS
CHALCOGENIDES
CHROMIUM COMPOUNDS
CRYSTAL STRUCTURE
ELEMENTS
ENERGY
FREE ENERGY
MAGNESIUM COMPOUNDS
MATERIALS
MECHANICAL PROPERTIES
METALS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
ZIRCONIUM COMPOUNDS
010404* - Coal
Lignite
& Peat- Gasification
360603 - Materials- Properties
360602 - Other Materials- Structure & Phase Studies