Slow Crack Growth in Polycrystalline Ceramics

Freiman, Stephen W.; McKinney, K. R.; Smith, H. L.

doi:10.1007/978-1-4615-7014-1_14

Cited by 64 publications

(17 citation statements)

References 10 publications

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“…The observed crack growth for the alumina/aluminum interface specimens was primarily intergranular in the alumina, and appeared to be identical to that observed in previous studies on moisture assisted crack growth in bulk alumina [60,107]. Initial moisture assisted crack growth in the 5 µm thick layer samples occurred at driving forces lower than for crack growth in fatigue pre-cracked bulk alumina samples.…”

Section: Discussionsupporting

confidence: 83%

Interfacial and near interfacial crack growth phenomena in metal bonded alumina

Kruzic

2001

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This study examines the mechanisms of interfacial and near interfacial crack propagation associated with the failure of sandwich specimens consisting of 99.5% pure polycrystalline alumina: 1) liquid state bonded with 99.999% pure aluminum layers and 2) partial transient liquid phase (PTLP) bonded using copper/niobium/copper interlayers.For the former system, the aluminum layer thickness was varied from 5 to 100 µm; it was found that the 3-point unnotched bending strength of the aluminum bonded joints increased, and the fracture toughness decreased, with decreasing layer thickness.Strength beams failed by ductile failure in the aluminum while fracture toughness samples failed by brittle fracture in the alumina. Under cyclic loading, crack growth occurred primarily by separating the aluminum from the alumina with evidence of ductile fatigue striations; cracks deviated into the alumina only for thin layered samples at high driving forces. Cyclic fatigue thresholds increased with decreasing layer thickness; however, the change to a brittle fatigue mechanism for thin layered samples at high driving forces was detrimental to the overall fatigue resistance. Under static loading in 2 moist air, interfacial separation was never observed at measurable rates (≥ 10 -9 m/sec); however, for 5 and 35 µm thick layered samples, cracks deviated off the interface and grew, sometimes stably, into the alumina resulting in time dependent failure.For alumina PTLP bonded with copper/niobium/copper interlayers, the mean interfacial fracture toughness was found to decrease from 39 J/m 2 to 21 J/m 2 as temperature was increased from 25 to 1000°C. At room temperature, cyclic fatigue crack propagation occurred at both the niobium/alumina interface and in the alumina, with higher fatigue thresholds resulting from a predominantly near interfacial (alumina) crack path. During both fracture and fatigue failure, residual copper at the interface deformed and remained adhered to both sides of the fracture surface, while separation of the niobium/alumina interface appeared essentially brittle in both cases. The observed behaviors of all samples are examined in terms of modulus mismatch effects, the level of plastic constraint, the relative crack propagation resistance of each observed crack path, the loading conditions, extrinsic toughening from ductile phase and/or alumina grain bridging, and environmental influences.i

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Section: Discussionsupporting

confidence: 83%

Interfacial and near interfacial crack growth phenomena in metal bonded alumina

Kruzic

2001

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“…The observed crack growth for the interface specimens was primarily intergranular in the alumina, and appeared to be identical to observed intergranular moisture-assisted crack growth in bulk alumina [27]. Although no interfacial moisture-assisted crack growth was observed, the interface may be nonetheless susceptible to moisture-assisted crack growth under conditions of reduced crack blunting and/or reduced propensity for cracking into the oxide substrate.…”

Section: Moisture-assisted Crack Growth Under Static Loadsupporting

confidence: 65%

Time Dependent Debonding of Aluminum/Alumina Interfaces under Cyclic and Static Loading

et al. 2000

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The structural integrity of oxide/metal interfaces is important in many applications. While most attention has focused on the debonding of oxide/metal interfaces by conducting strength and fracture toughness tests, very few investigations have looked at time dependant failure of interfaces under cyclic or static loading. Tests have been conducted on sandwich specimens consisting of 5 -100 micron thick aluminum layers bonded between either polycrystalline or single crystal Al 2 O 3 to determine cyclic fatigue-crack growth, as well as static loaded moistureassisted crack-growth, properties of Al/Al 2 O 3 interfaces. Under cyclic loading, crack growth was observed to occur predominantly by interfacial debonding, but was also observed to make excursions into the Al 2 O 3 . Static loading in a moist environment also caused interfacial cracks to deviate into the Al 2 O 3 or alternatively to arrest. Due to the poor crack growth resistance of the Al 2 O 3 , cracks leaving the interface grew at faster rates than those at the interface. Trends in crack trajectories and crack growth rates are explained in terms of the degree of plastic constraint in the aluminum layer, the modulus mismatch, and the effects of environmental mechanisms.

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“…Many tests have been carried out with the indentation technique (Tobin and Pak 1993;Lynch 1998;Shindo et al 2001;Schneider et al 2003). For many fracture experiments, polarized piezoelectric ceramics have been treated to be isotropic and use was made of purely mechanical calibrations for the stress intensity factor K I (Freiman et al 1974;Bruce et al 1978;McHenry and Koepke 1983;Pohanka et al 1983;Tobin and Pak 1993;Zhang et al 2004). The fracture toughness obtained in this way may be defined as the apparent fracture toughness and is typically referred to as K I c in the literature.…”

Section: Introductionmentioning

confidence: 99%

On fracture testing of piezoelectric ceramics

2009

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Fracture tests carried out on unpoled and poled PZT-5H four-point bend specimens are presented in this paper. The crack faces were parallel to the poling direction. Both mechanical loads and electric fields were applied to the poled specimens. The experimental results were analyzed by means of the finite element method and a conservative M-integral including the crack face boundary conditions. Fracture tests on fourpoint bend PIC-151 specimens with the crack faces perpendicular to the poling directions were also analyzed here; the experimental results were taken from the literature. A mixed mode fracture criterion is proposed for piezoelectric ceramics. This criterion is based upon the energy release rate and two phase angles. This criterion was implemented with experimental results from the literature and from this investigation. Excellent agrement was found between the fracture curve and the experimental results of the specimens with the crack faces perpendicular to the poling direction. With some scatter, reasonable agreement was observed between the fracture curve and the experimental results of the specimens with crack faces parallel to the poling direction.

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Slow Crack Growth in Polycrystalline Ceramics

Cited by 64 publications

References 10 publications

Interfacial and near interfacial crack growth phenomena in metal bonded alumina

Interfacial and near interfacial crack growth phenomena in metal bonded alumina

Time Dependent Debonding of Aluminum/Alumina Interfaces under Cyclic and Static Loading

On fracture testing of piezoelectric ceramics

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