Fracture Toughness of Advanced Structural Ceramics: Applying ASTM C1421

Journal Article · Mon Nov 03 00:00:00 EST 2014 · Journal of the American Ceramic Society

DOI:https://doi.org/10.1111/jace.13293· OSTI ID:1286775

Swab, Jeffrey J. ^[1]; Tice, Jason ^[1]; Wereszczak, Andrew A. ^[2]; Kraft, Reuben H. ^[1]

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1. Army Research Lab., Aberdeen, MD (United States)
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

The three methods of determining the quasi-static Mode I fracture toughness (K_Ic) (surface crack in flexure – SC, single-edge precracked beam – PB, and chevron notched beam – VB) found in ASTM C1421 were applied to a variety of advanced ceramic materials. All three methods produced valid and comparable KIc values for the Al₂O₃, SiC, Si₃N₄ and SiAlON ceramics examined. However, not all methods could successfully be applied to B₄C, ZrO₂ and WC ceramics due to a variety of material factors. The coarse-grained microstructure of one B₄C hindered the ability to observe and measure the precracks generated in the SC and PB methods while the transformation toughening in the ZrO₂ prevented the formation of the SC and PB precracks and thus made it impossible to use either method on this ceramic. The high strength and elastic modulus of the WC made it impossible to achieve stable crack growth using the VB method because the specimen stored a tremendous amount of energy prior to fracture. Even though these methods have passed the rigors of the standardization process there are still some issues to be resolved when the methods are applied to certain classes of ceramics. We recommend that at least two of these methods be employed to determine the K_Ic, especially when a new or unfamiliar ceramic is being evaluated.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE; US Army Research Laboratory (USARL); Work for Others (WFO)
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 1286775
• Journal Information: Journal of the American Ceramic Society, Vol. 98, Issue 2; ISSN 0002-7820
• Publisher: American Ceramic Society
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE