Crack growth rate, silicon nitrides

Early work (e.g., Refs. 44 and 45) on silicon nitride ceramics for a limited range of high temperature cyclic loading conditions led to the hypothesis that the mechanisms of cyclic and static fracture at elevated temperature are identical, and that the cyclic crack growth rates can be predicted on the basis of static fracture data. One of the techniques commonly used to derive cyclic crack growth rates solely on the basis of static load fracture data involves integration of the relationship in Eqn. (13) over the duration of the fatigue cycle such that... 

The subcritical crack growth rate in silicon nitride materials is relatively low in comparison to other ceramic materials. The growth exponent is in the range of... 

Figure 12.14 Crack growth rate versus stress dependenceofthecrackgrowthratefromonthe intensity factor for (a) a silicon nitride [88] and stress intensity factor. At higher temperatures,...

SCG rate steeply increases as Ki approaches the critical value Kic, leading to spontaneous fracture. In the case of sintered silicon nitrides at high temperatures, the fatigue limit is considered as the threshold between the crack healing and the crack growth. 

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