Relations between electrical breakdown field and mechanical properties of ceramics

The relationship between mechanical properties and electric breakdown has been investigated For this purpose, different ceramics, alumina with 2 grain sizes, zirconia, silicon nitride and mullite have been measured in terms of critical field and mechanical properties. The study has been conducted from a fracture mechanics point of view, i.e. rupture occurs from pre-existing flaws. The results show that different parameters play a role in the value of the critical field. The importance of the microstructure is demonstrated with the 2 aluminas that come from the same processing batch. Finally, the results are qualitatively described by a simple model based on the Griffith criterion.