Tensile fracture toughness of ceramic materials; Effects of dynamic loading and elevated temperatures

Journal Article · Wed Aug 01 04:00:00 EDT 1990 · Journal of the American Ceramic Society; (USA)

DOI:https://doi.org/10.1111/j.1151-2916.1990.tb07613.x· OSTI ID:6021649

Suresh, S; Nakamura, T; Yeshurun, Y; Yang, K H; Duffy, J ^[1]

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1. Brown Univ., Providence, RI (USA). Div. of Engineering

Experimental methods are presented for the determination of fracture initiation toughness of ceramics and ceramic composites in pure tension under quasi-static and dynamic loading conditions over a range of temperature spanning 20{degrees} to 1300{degrees}C. Circumferentially notched and cyclic fatigue precracked rods of a variety of ceramic materials were subjected to quasi-static tensile fracture (rate of stress intensity factor loading, K{sub I} {approx} 0.1 MPa {center dot} m {sup 1/2} {center dot} s{sup {minus}1}) in an electroservohydraulic test machine and to dynamic tensile fracture (K{sub I} {approx} 10{sup 6} MPa {center dot} m{sup 1/2} {center dot} s{sup {minus}1}) using a modified tensile Kolsky (split-Hopkinson) bar. For the quasi-static and dynamic fracture tests at elevated temperatures, the ceramic specimen was inserted into an air furnace where either friction grips or stress wave loading outside the furnace subjected the specimen to fracture. Dynamic finite-element analyses of the circumferentially notched cylindrical rod have been conducted to develop the optimum specimen dimensions and test procedures for the measurement of dynamic fracture toughness at ambient and elevated temperature. Experiments conducted on Al{sub 2}O{sub 3}, Si{sub 3}N{sub 4}, and SiC, and an Al{sub 2}O{sub 3}-25 vol% SiC whisker composite at room temperature indicate that the dynamic to quasi-static fracture initiation toughness ratio K{sub Id}/K{sub Ic} is in the range of 1.1 to 1.4. Elevated-temperature fracture tests for the polycrystalline Al{sub 2}O{sub 3} of 3-{mu}m average grain size reveal that K{sub Id} is only mildly sensitive to temperature over a range of 20{degrees} to 110{degrees}C, whereas it suffers a precipitous drop above 1100{degrees}C. Over the temperature range 20{degrees} to 1300{degrees}C, the ratio K{sub Id}/K{sub Ic} is found to be in the range 1.2 to 1.5.

• OSTI ID: 6021649
• Journal Information: Journal of the American Ceramic Society; (USA), Journal Name: Journal of the American Ceramic Society; (USA) Vol. 73:8; ISSN JACTA; ISSN 0002-7820
• 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
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CARBIDES
CARBON COMPOUNDS
CERAMICS
CHALCOGENIDES
CRACK PROPAGATION
CRYSTALS
DATA
DYNAMIC LOADS
ELECTRON MICROSCOPY
EXPERIMENTAL DATA
FINITE ELEMENT METHOD
INFORMATION
MECHANICAL PROPERTIES
MICROSCOPY
NITRIDES
NITROGEN COMPOUNDS
NUCLEATION
NUMERICAL DATA
NUMERICAL SOLUTION
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PNICTIDES
POLYCRYSTALS
SCANNING ELECTRON MICROSCOPY
SILICON CARBIDES
SILICON COMPOUNDS
SILICON NITRIDES
TENSILE PROPERTIES
VERY HIGH TEMPERATURE