Time-dependent mechanical behaviour of alumina ceramics

The strength of ceramics has been thought to be controlled by a stress corrosion mechanism, but experimental results which do not obey this mechanism have been reported recently. In this paper, dynamic fatigue test, static fatigue test, stress relaxation test and measurement of internal friction were carried out for the smooth specimens of alumina ceramics. Furthermore, we simulated the dynamic fatigue characteristics by using a viscoelastic model. From these results, it was shown that alumina ceramics have viscoelastic properties and their mechanical properties were also affected by this mechanism. In addition, we discuss the effects of added components and grain size on dynamic fatigue.