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An unconventional method for determining the fracture resistance of brittle materials is discussed. This method employs a conical indenter to chip the rectangular edge of the specimen. Particular features of the method are the use of small specimens and the evaluation of the resistance of materials to the nucleation, initiation and propagation of a crack. It is shown that this method is somewhat similar to the Hertzian fracture method and to the way that early man selected stones to make tools and weapons. Measured data of the fracture resistance of ceramics is presented. It is confirmed that if a ceramic material is similar to the model material of linear elastic fracture mechanics (LEFM), then those fracture resistance values are directly proportional to the critical stress intensity factors (baseline). For elastic and inelastic ceramics, R-lines characterizing the fracture resistance to crack growth are plotted. It is shown that proportionality lines (edge chipping resistance versus critical stress intensity factor) may be straight lines for ceramics with similar structure (such as Y-TZP and Mg-PSZ). The effect of rounding of the conical indenter tip (10–800 µm) on chip scar shape is indicated. Other aspects in the fracture behavior of ceramics during edge chipping are also analyzed. The advantages and disadvantages of the method are discussed. Further studies in this mechanico-physical research area are suggested.


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Edge chipping resistance of ceramics: Problems of test method

Show Author's information George A. GOGOTSI*( )
Pisarenko Institute for Problems of Strength, 2, Timiryazevskaya Str., 01014, Kiev, Ukraine

Abstract

An unconventional method for determining the fracture resistance of brittle materials is discussed. This method employs a conical indenter to chip the rectangular edge of the specimen. Particular features of the method are the use of small specimens and the evaluation of the resistance of materials to the nucleation, initiation and propagation of a crack. It is shown that this method is somewhat similar to the Hertzian fracture method and to the way that early man selected stones to make tools and weapons. Measured data of the fracture resistance of ceramics is presented. It is confirmed that if a ceramic material is similar to the model material of linear elastic fracture mechanics (LEFM), then those fracture resistance values are directly proportional to the critical stress intensity factors (baseline). For elastic and inelastic ceramics, R-lines characterizing the fracture resistance to crack growth are plotted. It is shown that proportionality lines (edge chipping resistance versus critical stress intensity factor) may be straight lines for ceramics with similar structure (such as Y-TZP and Mg-PSZ). The effect of rounding of the conical indenter tip (10–800 µm) on chip scar shape is indicated. Other aspects in the fracture behavior of ceramics during edge chipping are also analyzed. The advantages and disadvantages of the method are discussed. Further studies in this mechanico-physical research area are suggested.

Keywords:

mechanical characterization, micromechanics, indentation, phase transformation, edge fracture (EF) method
Received: 21 July 2013 Revised: 15 October 2013 Accepted: 30 October 2013 Published: 04 December 2013 Issue date: December 2013
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Publication history

Received: 21 July 2013
Revised: 15 October 2013
Accepted: 30 October 2013
Published: 04 December 2013
Issue date: December 2013

Copyright

© The author(s) 2013

Acknowledgements

The author is grateful to V. Galenko for technical assistance.

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Open Access: This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.

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