Development of a creep deformation and life prediction model for a HIPed silicon nitride ceramic

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

OSTI ID:7253500

Ding, J L ^[1]; Liu, K C; Brinkman, C R ^[2]

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1. Washington State Univ., Pullman, WA (United States). Dept. of Mechanical Engineering
2. Oak Ridge National Lab., TN (United States)

A mathematical model was developed for predicting creep deformation and creep-rupture time for a HIPed silicon nitride (Si{sub 3}N{sub 4}) ceramic subjected to thermal-mechanical loading in uniaxial tension at elevated temperatures. The model was formulated based on the deformation and rupture data obtained from a systematic experimental study on a single lot of GN-10 Si{sub 3}N{sub 4}; however, it is applicable in principle to other types of ceramic materials. The model consists of three rate-type of equations that describe changes of three variables representing creep strain, devitrification of second phase, and creep damage. Introduction of the devitrification and creep damage variables is a new approach in constitutive modelling of Si{sub 3}N{sub 4} ceramics and has significantly enhanced the ability to predict effects of annealing on creep behavior and creep rupture lifetime. Although the proposed model is exploratory in nature, it has demonstrated the capability of describing the essential features of uniaxial creep and creep rupture behavior of the material subjected to both constant and stepwise-varied loading conditions as well as the effects of high temperature annealing on the subsequent creep and creep rupture behavior. The simplicity of the model makes the closed form solutions for constant or stepwise-varied loading possible and, therefore, facilitates adoption of the proposed model in the current engineering design and analysis methods.

• Research Organization: Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 7253500
• Report Number(s): CONF-9211101-1; ON: DE93000980
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360203* -- Ceramics
Cermets
& Refractories-- Mechanical Properties
ANNEALING
CREEP
DEFORMATION
FAILURES
HEAT TREATMENTS
LIFETIME
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
NITRIDES
NITROGEN COMPOUNDS
PNICTIDES
RUPTURES
SILICON COMPOUNDS
SILICON NITRIDES
TEMPERATURE RANGE
TEMPERATURE RANGE 1000-4000 K