Chevron-Notched, Flexure Tests for Measuring the Elevated-Temperature Fracture Resistance of Structural Ceramics

Conference · Wed Jan 01 00:00:00 EST 1992 · Journal of ASTM International

DOI:https://doi.org/10.1520/stp24717s· OSTI ID:6108657

Jenkins, Michael G. ^[1]; Ferber, Mattison K. ^[1]; Ghosh, Asish ^[2]; Peussa, Jouko T. ^[3]; Salem, Jonathan A. ^[4]

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1. Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
2. Philips Display Components Company, Ann Arbor, MI (United States)
3. Federation of Finnish Metal, Engineering, and Electronic Technology Industries, Helsinki (Finland)
4. NASA Lewis Research Center, Cleveland, OH (United States)

Chevron-notched, three-point flexure specimens were used to study the quasi-static fracture behaviour of a variety of structural ceramics at temperatures to 1400°C. Types of materials tested included monolithic ceramics (SiC, Si₃N₄, MgAl₂O₄), self-reinforced monoliths (acicular grained Si₃N₄, acicular grained mullite), and ceramic matrix composites (SiC whisker/AI₂O₄ matrix, TiB₂ particulate/SiC matrix, SiC fibre/CVI SiC matrix, AI₂O₃ fibre/CVI SiC matrix). Fracture resistance behaviour of the materials was quantified as three distinct regimes of the fracture histories. At crack initiation, the apparent fracture toughness was evaluated as the critical stress intensity factor, K_IvM. During stable crack propagation, the crack growth resistance was characterized by the instantaneous strain energy release rate, G_R, using a compliance method assuming linear elastic unloading to calculate the effective crack lengths. At final fracture, the complete fracture process was quantified using the work-of-fracture, γ_WOF. which can be equated to the fracture surface energy for linear-elastic materials. Results indicate that the chevron-notched, three-point flexure specimen facilitates the study of fracture behaviour in a wide range of brittle and quasi-brittle materials at elevated temperatures. The unique features of the chevron geometry, which are automatic crack initiation and inherent stable crack growth are crucial to the successful evaluation of the fracture tests.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6108657
• Report Number(s): CONF-9105138-1; ON: DE91009117
• Journal Information: Journal of ASTM International, Conference: Chevron-Notch Fracture Test Experience Metals and Non-Metals Conference, Indianapolis, IN (United States), 6 May 1991
• Publisher: ASTM International
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
SILICON CARBIDES
FRACTURE PROPERTIES
SILICON NITRIDES
ALUMINIUM OXIDES
COMPOSITE MATERIALS
CRACK PROPAGATION
MAGNESIUM OXIDES
MATERIALS TESTING
MULLITE
REINFORCED MATERIALS
VERY HIGH TEMPERATURE
ALKALINE EARTH METAL COMPOUNDS
ALUMINIUM COMPOUNDS
CARBIDES
CARBON COMPOUNDS
CHALCOGENIDES
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
MAGNESIUM COMPOUNDS
MATERIALS
MECHANICAL PROPERTIES
MINERALS
NITRIDES
NITROGEN COMPOUNDS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PNICTIDES
SILICON COMPOUNDS
TESTING
elevated temperature
fracture resistance
R-curve
work-of-fracture ceramics
stable crack growth
chevron notch
360203* - Ceramics
Cermets
& Refractories- Mechanical Properties