Fractography and the Surface Crack in Flexure (SCF) method for evaluating fracture toughness of ceramics

Conference · Tue Dec 31 04:00:00 EST 1996

OSTI ID:535632

Quinn, G D; Gettings, R J ^[1]; Kuebler, J J ^[2]

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1. National Institute of Standards Technology, Gaithersburg, MD (United States)
2. Swiss Federal Laboratories for Materials Testing and Research, Dubendorf (Switzerland)

The surface crack in flexure (SCF) method, also known as the controlled surface flaw method, has been used to measure fracture toughness of ceramics and glasses for almost 20 years. New fracture toughness results for a range of ceramics and glasses including alumina, boron carbide, silicon carbide, silicon nitride, titanium diboride, zirconia, glass ceramic, borosilicate crown glass, and a whisker-reinforced alumina are presented in this paper. Some materials are conducive to precrack measurements, while others are not. New techniques for detecting the precracks are presented. A surprising outcome from a recently concluded Versailles Advanced Materials and Standards (VAMAS) round robin project was that the computed toughness is often not sensitive to the exact precrack size measurement. Consistent results were obtained by many laboratories despite different viewing modes and magnifications. The reasons for this consistency and why toughness is insensitive to precrack size is presented.

• DOE Contract Number: AC05-84OR21400
• OSTI ID: 535632
• Report Number(s): CONF-950739--
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM OXIDES
BORON CARBIDES
CERAMICS
CRACKS
FRACTOGRAPHY
FRACTURE PROPERTIES
SILICON CARBIDES
SILICON NITRIDES
TITANIUM BORIDES
ZIRCONIUM OXIDES