L. Zou et al. Journal European Ceramic Society 23(2003)1987-1996 G Displacement, u( mm) Displacement, u(mm) Fig 4. The three-point bending test and interfacial toughness calculation results for the bn Al2O3 interphase system. (a)BN+ 16vol %Al20 (b)Bn+ 36vol %Al2O3;(c)BN 63vol %AlO3:(d) AlO3 110 SiNA Modifier ▲ALO2 Modifier 80 30 SiNA or AlO3 vol% Fig. 5. The dependence of interfacial toughness on volume fraction of Si3 N4 or Al2O3 modifierFig. 5. The dependence of interfacial toughness on volume fraction of Si3N4 or Al2O3 modifier. Fig. 4. The three-point bending test and interfacial toughness calculation results for the BN + Al2O3 interphase system. (a) BN + 16vol.%Al2O3; (b) BN + 36vol.%Al2O3; (c) BN + 63vol.%Al2O3; (d) Al2O3. L. Zou et al. / Journal of the European Ceramic Society 23 (2003) 1987–1996 1991