International ournal of Applied Ceramic Technolog-Nozawa and Tanigawa Vol.7,No.3,2010 NITE-Thin-Coat NITE-Thick-Coat 0001002003004005006 Strain [%] Strain [%J tensile fracture behaviors of a) nanoinfltration transient eutectic(NITEr and(b) polymer-impregnation Results ductility. The big difference was in the high fracture strain (0.9%)compared with those of NITE-SiC/SiC com- Tensile Properties posites(<0.1%). Additionally, the proportional limit Figure 3 shows typical tensile stress versus strain stress(PLS), that is, an equivalent stress when matrix cracking initiates, was low ( 30 MPa)due to the brittle curves of SiC/SiC composites by the standard tensile PIp-SiC matrix For both types of NITE-SiC/SiC com- rest and reduced data are listed in Table l. the nite- Thin-Coat composite exhibited brittle fracture. The scan- posites, the PLS was quite high(<150 MPa)due to im- brittle surface probably due to the strong bonding at the by the NITe prolif Ensity of the SiC matrix produced proved stiffness and der ning electron microscope image(Fig 4a)clearly shows the F/M interface. No fiber pullout was observed in the frac- SENB Test Results ture surface. In contrast, NITE-Thick-Coat showed quasi- ductility coupled with fiber pullouts due to the cumulative Figure 5 shows a typical load versus COD curve debonding until fracture(Fig. 4b). However, the total during SENB tests for NITE-Thick-Coat and Fig.6ex- elongation was not so significant even in this case. In contrast, the PIP-Coat composite showed better quasi- ing stage of the SENB-3 specimen. From Fig NITE-Thin ick-Coa 50 Fig 4. Typical fracture surface images of nanoinfilration transient-eutectic(NITESiC/SiC compositesResults Tensile Properties Figure 3 shows typical tensile stress versus strain curves of SiC/SiC composites by the standard tensile test and reduced data are listed in Table I. The NITE￾Thin-Coat composite exhibited brittle fracture. The scan￾ning electron microscope image (Fig. 4a) clearly shows the brittle surface probably due to the strong bonding at the F/M interface. No fiber pullout was observed in the frac￾ture surface. In contrast, NITE-Thick-Coat showed quasi￾ductility coupled with fiber pullouts due to the cumulative debonding until fracture (Fig. 4b). However, the total elongation was not so significant even in this case. In contrast, the PIP-Coat composite showed better quasi￾ductility. The big difference was in the high fracture strain (B0.9%) compared with those of NITE–SiC/SiC com￾posites (o0.1%). Additionally, the proportional limit stress (PLS), that is, an equivalent stress when matrix￾cracking initiates, was low (B30 MPa) due to the brittle PIP–SiC matrix. For both types of NITE–SiC/SiC com￾posites, the PLS was quite high (B150 MPa) due to im￾proved stiffness and density of the SiC matrix produced by the NITE process. SENB Test Results Figure 5 shows a typical load versus COD curve during SENB tests for NITE-Thick-Coat and Fig. 6 ex￾hibits typical specimen surface micrographs in each load￾ing stage of the SENB-3 specimen. From Fig. 5, Fig. 4. Typical fracture surface images of nanoinfiltration transient-eutectic (NITE)–SiC/SiC composites. Fig. 3. Typical tensile fracture behaviors of (a) nanoinfiltration transient-eutectic (NITE)– and (b) polymer-impregnation and pyrolysis (PIP)–SiC/SiC composites. 308 International Journal of Applied Ceramic Technology—Nozawa and Tanigawa Vol. 7, No. 3, 2010