Fracture Toughness of Amorphous Precursor‐Derived Ceramics in the Silicon‐Carbon‐Nitrogen System

The toughness of amorphous precursor-derived ceramics in the Si-C-N system is investigated. Crack-growth data are obtained from DCB specimens, whereas the crack-tip toughness is determined from the crack-tip profile of indentation cracks. For amorphous Si-C-N ceramics that have been fabricated via the powder route, an R-curve effect is observed. The initial values of the rising R-curve are consistent with the estimated crack-tip toughness.