Effects of [alpha]-SiC versus [beta]-SiC starting powders on microstructure and fracture toughness of SiC sintered with Al[sub 2]O[sub 3]-Y[sub 2]O[sub 3] additives

Journal Article · Wed Jun 01 04:00:00 EDT 1994 · Journal of the American Ceramic Society; (United States)

DOI:https://doi.org/10.1111/j.1151-2916.1994.tb09771.x· OSTI ID:7072084

Lee, S K; Kim, C H ^[1]

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1. Korea Advanced Inst. of Science and Technology, Taejon (Korea, Republic of). Dept. of Ceramic Science and Engineering

Dense SiC ceramics were obtained by pressureless sintering of [beta]-SiC and [alpha]-SiC powders as starting materials using Al[sub 2]O[sub 3]-Y[sub 2]O[sub 3] additives. The resulting microstructure depended highly on the polytypes of the starting SiC powders. The microstructure of SiC obtained from [alpha]-SiC powder was composed of equiaxed grains, whereas SiC obtained from [beta]-SiC powder was composed of a platelike grain structure resulting from the grain growth associated with the [beta][r arrow][alpha] phase transformation of SiC during sintering. The fracture toughness for the sintered SiC using [alpha]-SiC powder increased slightly from 4.4 to 5.7 MPa [center dot] m[sup 1/2] with holding time, that is, increased grain size. In the case of the sintered SiC using [beta]-SiC powder, fracture toughness increased significantly from 4.5 to 8.3 MPa [center dot] m[sup 1/2] with holding time. This improved fracture toughness was attributed to crack bridging and crack deflection by the platelike grains.

• OSTI ID: 7072084
• Journal Information: Journal of the American Ceramic Society; (United States), Journal Name: Journal of the American Ceramic Society; (United States) Vol. 77:6; ISSN 0002-7820; ISSN JACTAW
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360203 -- Ceramics
Cermets
& Refractories-- Mechanical Properties
ADDITIVES
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CARBIDES
CARBON COMPOUNDS
CHALCOGENIDES
DATA
EXPERIMENTAL DATA
FABRICATION
FRACTURE PROPERTIES
INFORMATION
MECHANICAL PROPERTIES
MICROSTRUCTURE
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
SILICON CARBIDES
SILICON COMPOUNDS
SINTERING
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
YTTRIUM OXIDES