Subcritical crack growth of a ceramic component

In a plant producing common salt, a connecting pin is to be used that has to service in concentrated saline solution at a temperature of 70 °C. The pin is loaded at a stress of Cservice = 100 MPa. The component has to serve for 25000 hours with a failure probability of 0.5% at most. Due to the aggressive environment, a metal cannot be used for the pin. Instead, hot isostatic pressed aluminium oxide (AI2O3) is to be used, characterised by the following parameters  

The geometry factor of the connecting pin is y = 1.3. The maximum crack growth resistance has been measured to 

---