Silicon nitrides static load rating

In this section, noticing the occurrence of cracks in silicon nitride, the static load rating was studied for an all ceramic bearing, in which silicon nitride is used for the inner and outer rings and balls. (This is because if silicon nitride is loaded, cracks appear usually without the occurrence of permanent deformation.) [7, 8]. 

Consequently, it can be seen that an all-ceramic bearing made of silicon nitride can well withstand the same load as the static load rating of a conventional steel bearing, and that there are no problems at all in their practical use in terms of their static load rating. 

Fujiwara, T., Yoshioka, T., Kitahara, T., Koizumi, S., Takebayashi, H., and Tada, T. (1988). Study on load rating property of silicon nitride of rolling bearing materials, J. JSLE 33 301. Yoshioka, T., Kitahara, T., Takebayashi, H., and Yuine, T. (1989). A new method for static load rating of ceramic rolling bearing. Wear 133 373. 

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... 

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