Dynamic fatigue behaviour of a steatite ceramic

Dynamic fatigue of a low dielectric loss steatite was investigated. To this end, the values of n and B, the so‐called subcritical crack growth (SCG) parameters were experimentally determined. The steatite exhibited the expected dynamic fatigue behaviour, so that the stress corrosion susceptibility p...

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Bibliographic Details
Published in:Materialwissenschaft und Werkstofftechnik 2016-09, Vol.47 (9), p.797-807
Main Authors: Costa Oliveira, F. A., Reboredo, H., Cruz Fernandes, J.
Format: Article
Language:English
Subjects:
Alloys
Biegefestigkeit
Bruchzähigkeit
dynamic fatigue
Dynamics
dynamische Ermüdung
Fatigue (materials)
flexural strength
Fracture mechanics
fracture toughness
Inert
langsames Risswachstum
Metal fatigue
Parameters
slow crack growth
Steatit
Steatite
Strength
Talcs
Test methods
Test procedures
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Summary:Dynamic fatigue of a low dielectric loss steatite was investigated. To this end, the values of n and B, the so‐called subcritical crack growth (SCG) parameters were experimentally determined. The steatite exhibited the expected dynamic fatigue behaviour, so that the stress corrosion susceptibility parameter, n, of 24 was obtained. In addition, the material/environment parameter B, which is a constant for a given test environment, was also attained. These parameters are instrumental in predicting the lifetime of components under stress. When the applied load is such that the resulting strength equals half of the inert strength (σi), defined as the strength of a sample tested in an inert environment or at a fast stress rate, i.e. where no subcritical crack growth occurs, the time to failure (tf) of the material was found to be ∼140 h. Measurement of the fracture toughness of steatite is also of upmost importance and so it was determined using three test methods. A value of KIc = 1.91 ± 0.29 MPa m1/2 was attained by the indentation fracture method through measurement of the cracks emanating from the Vickers indentation. This value is in good agreement with those determined using the KIsc (surface crack in flexure) test method (2.21 ± 0.07 MPa m1/2) and fractography analysis test method (2.00 ± 0.44 MPa m1/2). Differences in test procedure and analysis causing the values from each test method to be different are discussed.
ISSN:0933-5137
1521-4052
DOI:10.1002/mawe.201600552