Creep and slow crack growth mechanisms related to macroscopic creep behaviour of a silicon nitride ceramic at elevated temperatures

Conference · Wed Jan 01 04:00:00 EST 1992

OSTI ID:5266734

Jenkins, M G; Ferber, M K ^[1]; Salem, J A ^[2]

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1. Oak Ridge National Lab., TN (United States)
2. National Aeronautics and Space Administration, Cleveland, OH (United States). Lewis Research Center

Recent tensile creep and creep rupture test results of a hot isostatically pressed silicon nitride at 1150, 1260, and 1370{degrees}C were evaluated using microscopy in conjunction with various empirical and mathematical models to provide insight into creep and slow crack growth mechanisms. The stress and temperature sensitivities with dominant creep mechanism. Limiting cases for cavity nucleation and growth were applied to establish possible creep damage modes. At 1150{degrees}C, creep rupture was controlled by a slow crack growth mechanism. At 1260 and 1370{degrees}C, the accumulation of creep damage in the form of grain boundary cavities and cracks dominated the creep rupture behaviour. In this temperature regime, the creep rupture life was controlled by the secondary (or minimum) strain rate in accordance with a Monkman-Grant-type relation.

• Research Organization: Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5266734
• Report Number(s): CONF-9206187-1; ON: DE92015195
• 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
CRACK PROPAGATION
CREEP
CRYSTAL STRUCTURE
FABRICATION
HOT PRESSING
MATERIALS WORKING
MECHANICAL PROPERTIES
MICROSTRUCTURE
NITRIDES
NITROGEN COMPOUNDS
PNICTIDES
PRESSING
SILICON COMPOUNDS
SILICON NITRIDES
STRAIN RATE
TEMPERATURE DEPENDENCE