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Cyclic Fatigue from Frictional Degradation at Bridging Grains in Alumina

Lathabai, Srinivasarao and Rödel, Jürgen and Lawn, Brian R. (1991):
Cyclic Fatigue from Frictional Degradation at Bridging Grains in Alumina.
In: Journal of the American Ceramic Society, pp. 1340-1348, 74, (6), ISSN 0002-7820,
[Online-Edition: http://dx.doi.org/10.1111/j.1151-2916.1991.tb04109.x],
[Article]

Abstract

ension—tension cyclic loading tests have been conducted on a coarse-grained alumina ceramic that exhibits toughnesscurve behavior by grain-interlock bridging. Fatigue effects are observed in the regions of both short cracks, using indentation flaws, and long cracks, using compact-tension specimens. A true mechanical fatigue effect is demonstrated by running the tests below the static fatigue limit. A custom-made device for in situ observation of crack propagation in the scanning electron microscope enables us to identify bridge degradation as a cause of the fatigue process. “Wear” debris cumulates at the sliding intergranular frictional contact points, indicating a loss of traction at the junction. The basis of a fracture mechanics model describing the effect of this frictional degradation in reducing crack-tip shielding is outlined and fitted to the data. It is suggested that the bridge degradation fatigue mechanism may be widespread in polycrystalline ceramics with pronounced toughness curves.

Item Type: Article
Erschienen: 1991
Creators: Lathabai, Srinivasarao and Rödel, Jürgen and Lawn, Brian R.
Title: Cyclic Fatigue from Frictional Degradation at Bridging Grains in Alumina
Language: English
Abstract:

ension—tension cyclic loading tests have been conducted on a coarse-grained alumina ceramic that exhibits toughnesscurve behavior by grain-interlock bridging. Fatigue effects are observed in the regions of both short cracks, using indentation flaws, and long cracks, using compact-tension specimens. A true mechanical fatigue effect is demonstrated by running the tests below the static fatigue limit. A custom-made device for in situ observation of crack propagation in the scanning electron microscope enables us to identify bridge degradation as a cause of the fatigue process. “Wear” debris cumulates at the sliding intergranular frictional contact points, indicating a loss of traction at the junction. The basis of a fracture mechanics model describing the effect of this frictional degradation in reducing crack-tip shielding is outlined and fitted to the data. It is suggested that the bridge degradation fatigue mechanism may be widespread in polycrystalline ceramics with pronounced toughness curves.

Journal or Publication Title: Journal of the American Ceramic Society
Volume: 74
Number: 6
Uncontrolled Keywords: fatigue; friction; degradation; grains; bridging
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Nonmetallic-Inorganic Materials
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 13 Jun 2012 13:41
Official URL: http://dx.doi.org/10.1111/j.1151-2916.1991.tb04109.x
Identification Number: doi:10.1111/j.1151-2916.1991.tb04109.x
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