K K. Chawla et al. Journal of the European Ceramic Society 20(2000)551-559 3. 1. Interfacial Roughness mechanical keying, which can prevent interfacial debonding and fiber pullout, while a smooth interface The degree of interfacial roughness is a very leads to weak keying, which is desirable for fiber pull tant factor in a mechanically bonded interface. 2 out. Many investigators 5-18 studied interfacial rough large interfacial hess usually results in ness and found that interfacial roughness had Thin Interphase Mode Saphikon Interfacial debonding Matrix (a) Thick Interphase Model Interphase fracture Matrix (b) Fig. 8. Schematic of the interfacial debonding models for thin and thick interphase: (a) thin interphase model wherein debonding occurs by a single crack along the Saphikon fiber/monazite interface; (b) thick interphase model wherein debonding occurs by the coalescence of microcracks within the monazite coating. 0.10 0.15 0.25 Displacement (mm) Fig 9. The stress-displacement curves of a five-dip composite and monolithic alumina in a three-point bend test at room temperature. Note that the fiber volume fraction in the composite was very small, about 0.013.1. Interfacial Roughness The degree of interfacial roughness is a very impor￾tant factor in a mechanically bonded interface.2 A very large interfacial roughness usually results in strong mechanical keying, which can prevent interfacial debonding and ®ber pullout, while a smooth interface leads to weak keying, which is desirable for ®ber pull￾out. Many investigators15±18 studied interfacial rough￾ness and found that interfacial roughness had a Fig. 9. The stress±displacement curves of a ®ve-dip composite and monolithic alumina in a three-point bend test at room temperature. Note that the ®ber volume fraction in the composite was very small, about 0.01. Fig. 8. Schematic of the interfacial debonding models for thin and thick interphase: (a) thin interphase model wherein debonding occurs by a single crack along the Saphikon ®ber/monazite interface; (b) thick interphase model wherein debonding occurs by the coalescence of microcracks within the monazite coating. 556 K.K. Chawla et al. / Journal of the European Ceramic Society 20 (2000) 551±559