View article

Crack bridging mechanisms in self-reinforced silicon nitride ceramics rely on interfacial debonding and intergranular fracture processes. The toughening effects can be enhanced by increasing the diameter of the elongated grains. However, the composition of the additives and, hence, the grain boundary amorphous phase can significantly alter this response; the question remains as to whether this is due to interfacial structure and bonding or the state of residual stresses. Here studies of debonding of the interfaces associated with β-Si₃N₄ whiskers embedded in oxynitride glasses are used to examine the role of oxynitride glass composition on the debonding behavior. Using indentation cracking, measurements of interfacial debond lengths versus angle of incidence (i.e. between crack plane and interface plane) are used to determine the critical angle for debonding which can be related to debonding energy. In Si …