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

Abstract

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.

Authors:
;
Publication Date:
Research Org.:
Argonne National Lab., IL (USA). Materials and Components Technology Div.
OSTI Identifier:
6436828
Report Number(s):
CONF-881207-3
ON: DE89009847
DOE Contract Number:  
W-31109-ENG-38
Resource Type:
Conference
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
Subject:
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

Citation Formats

Singh, J P, and Poeppel, R B. Fracture toughness of MgCr/sub 2/O/sub 4/-based refractory composites. United States: N. p., 1988. Web.
Singh, J P, & Poeppel, R B. Fracture toughness of MgCr/sub 2/O/sub 4/-based refractory composites. United States.
Singh, J P, and Poeppel, R B. 1988. "Fracture toughness of MgCr/sub 2/O/sub 4/-based refractory composites". United States. https://www.osti.gov/servlets/purl/6436828.
@article{osti_6436828,
title = {Fracture toughness of MgCr/sub 2/O/sub 4/-based refractory composites},
author = {Singh, J P and Poeppel, R B},
abstractNote = {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.},
doi = {},
url = {https://www.osti.gov/biblio/6436828}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Nov 01 00:00:00 EST 1988},
month = {Tue Nov 01 00:00:00 EST 1988}
}

Conference:
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