Crack growth and cyclic fatigue behaviour of sintered silicon nitride and syalon.

In the past years, various high-performance ceramics were developed, but their technical application is still limited. In order to extend the applicability of the high-performance ceramics, the knowlege of relevant properties is necessary. In this paper, we will present some results regarding the fatigue behaviour of two commercial silicon nitrides in the temperature range from 23 to 700 degree C. The studies include the macroiscopic crack growth and the dynamic cyclic fatigue behaviour at different frequencies. The correlation between subcritical crack growth and fatigue behaviour is examined. In view of the application of these ceramics in combustion engines, the influence of exhaust gas on the cyclic fatigue behaviour is investigated.