K Shimoda et al. Composites Science and Technology 68(2008)98-105 3um ig. 2. Cross-sections of uncoated and PyC coated SA fibers formed with CVD technique: (a)uncoated, (b)CVD-0 25, (c)CVD-050 and(d)CVD-100. Table 3 Density and porosity of hot-pressed composites with various interface conditions Uncoated CVD-0.50 CVD-1.00 ED: experimental density, TD: theoretical density. a=3PL/2wt (1) (2) E=0.25Lm/wt3, ▲yAlO1YAG where P is load at a point of deflection of a load-displace ment curve in test, L is outer support span, w is specimen width, t is specimen thickness, D is deflection at beam cen- ter at a given point in the test and m is slop of tangent to the initial straight-line portion of the load-deflection curve Polished cross sections and fracture surface after bend ing test of hot-pressed composites were observed by field emission scanning electron microscopy constitution phases of the matrix were identified by X-ray 607080 diffractometry(XRD), using monolithic SiC fabricated by e/degree(Cu Ko) he same processing condition for SiC/SiC composites in Fig 3.x-ray diffraction profile of the monolithic Sic fabricated by the this study.r ¼ 3PL=2wt2 ð1Þ e ¼ 6Dt=L2 ð2Þ E ¼ 0:25 L3 m=wt3 ; ð3Þ where P is load at a point of deflection of a load–displace￾ment curve in test, L is outer support span, w is specimen width, t is specimen thickness, D is deflection at beam cen￾ter at a given point in the test and m is slop of tangent to the initial straight-line portion of the load–deflection curve. Polished cross sections and fracture surface after bend￾ing test of hot-pressed composites were observed by field emission scanning electron microscopy (FE-SEM). The constitution phases of the matrix were identified by X-ray diffractometry (XRD), using monolithic SiC fabricated by the same processing condition for SiC/SiC composites in this study. Fig. 2. Cross-sections of uncoated and PyC coated SA fibers formed with CVD technique: (a) uncoated, (b) CVD-0.25, (c) CVD-0.50 and (d) CVD-1.00. Table 3 Density and porosity of hot-pressed SiC/SiC composites with various interface conditions Density (mg/m3 ) Open porosity (%) ED/TDa (%) Fiber volume (%) Uncoated 3.15 1.6 99 55 CVD-0.25 3.10 1.5 95 42 CVD-0.50 3.01 3.3 92 48 CVD-1.00 2.84 6.9 87 46 a ED: experimental density, TD: theoretical density. Fig. 3. X-ray diffraction profile of the monolithic SiC fabricated by the same condition for SiC/SiC composites. 100 K. Shimoda et al. / Composites Science and Technology 68 (2008) 98–105