wwceramics. org/ACT SiC Fiber-Reinforced MI SiC Composites 153 Table I. Composite Phy fber specimen Average f radius [ specimens] Average Average (um)per tow epcm (mm) (scatter) SYLiBN-1 Sylramic-iBN 5 226[1 0.352[11 0.1140.286 (+0.07/-0.19)(+0.014/-0.004) SYLiBN-2 Sylramic-iBN 5 0.386[10] 0.1570.287 (+0.14/-0.12)(+0.026/-0.022) SYLiBN-3 Sylramic-iB 5 800 1.93[10] 0.410[10 0.130.270 0.09 (+0.02/-0.018) SA-1 Tyranno SA3 5 8007.12.057 0.348[7] 0.1200.281 (+0.06/-0.12)(+0.02/-0.01) Tyranno SA3 5 5] 0.3625] 0.281 (+0.04/-0.05)( SA-3 yranno SA3 5 800 215[10 0.332[10 0.098 0.274 (+0.05/-0.08)(+0.006/-0.004) Hi-Nicalon 500 7.1 0.0390.227 (+0.1l/-0.13)(+0.012/-0.01) Tyranno ZMI 5.5 800 3.759 0.227 (+0.004/-0.006 Z-2 Tyranno ZMI 5.5 8.7 362{4] 0.292[4] 0.072 0.198 (+0.12/-0.14)(+0.01/-0.01) HNS-1 Hi-Nicalon S 6.5 5007.12.49团7] 0.3029 (+0.04/-0.09)(+0.012/-0.004) Hi-Nicalon S 6.5 50 217[9 0.3489] 0.040.21 (+0.08/-0.12)(+0.020/-0.018) The preforms were detooled after CVI SiC infiltration. Therefore, the volume of BN could not be measured volume of BN was estimated from average BN thickness measurements of polished specimens. The volume of Sic after CVI infiltration after subtracting the estimated weight of Bn and the known weights of the fibers for the p: i diret d rom lined from the weight gain The fiber. BN, and Cy SiC densities used were 3.05, 1.5, and 3.2 g/cm,, respectively Elevated temperature tensile -rupture tests Results were performed at 1200.C and 1315.C in ambient air on a different machine(Instron Model 5569), which had a resistance-heated MoSiz element furnace inserted into the center of the dog-bone section. The ends of the Table i lists the nominal and calculated values for tensile bars in these tests were also encased in a wire key properties of the constituents in each composite mesh, but the pneumatic grips were water cooled. A panel, based on in-process data and data measured contact extensometer with SiC contacting pins 25 mm on the final processed panels and test specimens apart from one another was used to measure strain at the Because the woven architectures for all panels were bal- edge of the specimen in the gauge section Displacement anced in fiber content in the two orthogonal directions, was measured with an LVDT that featured a maximum the fiber volume fraction in the tensile loading direc- strain capability of 1%. Before the elevated temperature tion, f o, was half of the total fiber volume. For this creep test, a tensile modulus measurement was made on study, fo was determined from the estimated total fiber each specimen over the stress range 5-50 MPa at room area in the loading direction divided by the measured physical area of the composite specimen in theElevated temperature tensile creep-rupture tests were performed at 12001C and 13151C in ambient air on a different machine (Instron Model 5569), which had a resistance-heated MoSi2 element furnace inserted into the center of the dog-bone section. The ends of the tensile bars in these tests were also encased in a wire mesh, but the pneumatic grips were water cooled. A contact extensometer with SiC contacting pins 25 mm apart from one another was used to measure strain at the edge of the specimen in the gauge section. Displacement was measured with an LVDT that featured a maximum strain capability of 1%. Before the elevated temperature creep test, a tensile modulus measurement was made on each specimen over the stress range 5–50 MPa at room temperature. Results Constituent Analyses Table I lists the nominal and calculated values for key properties of the constituents in each composite panel, based on in-process data and data measured on the final processed panels and test specimens. Because the woven architectures for all panels were bal￾anced in fiber content in the two orthogonal directions, the fiber volume fraction in the tensile loading direc￾tion, fo, was half of the total fiber volume. For this study, fo was determined from the estimated total fiber area in the loading direction divided by the measured physical area of the composite specimen in the gauge Table I. Composite Physical Properties Panel Fiber type Average fiber radius (lm) # of fibers per tow epcm Average specimen thickness (mm) Average f [# specimens] (scatter) Average fBN Average fCVI SiC SYLiBN-1 Sylramic-iBN 5 800 7.9 2.26 [11] 0.352 [11] 0.114 0.286 (10.07/0.19) (10.014/0.004) SYLiBN-2 Sylramic-iBN 5 800 7.9 2.05 [10] 0.386 [10] 0.157 0.287 (10.14/0.12) (10.026/0.022) SYLiBN-3 Sylramic-iBN 5 800 7.9 1.93 [10] 0.410 [10] 0.134 0.270 70.09 (10.02/0.018) SA-1 Tyranno SA3 5 800 7.1 2.05 [7] 0.348 [7] 0.120 0.281 (10.06/0.12) (10.02/0.01) SA-2 Tyranno SA3 5 800 7.1 1.97 [5] 0.362 [5] 0.126 0.281 (10.04/0.05) (70.008) SA-3 Tyranno SA3 5 800 7.1 2.15 [10] 0.332 [10] 0.098 0.274 (10.05/0.08) (10.006/0.004) HN Hi-Nicalon 6.85 500 7.1 3.05 [7] 0.274 [7] 0.039 0.227 (10.11/0.13) (10.012/0.01) Z-1 Tyranno ZMI 5.5 800 8.7 3.75 [9] 0.281 [9] 0.082 0.227 10.06 (10.004/0.006) Z-2 Tyranno ZMI 5.5 800 8.7 3.62 [4] 0.292 [4] 0.072 0.198 (10.12/0.14) (10.01/0.01) HNS-1 Hi-Nicalon S 6.5 500 7.1 2.49 [7] 0.302 [9] 0.04 0.25 (10.04/0.09) (10.012/0.004) HNS-2 Hi-Nicalon S 6.5 500 7.1 2.17 [9] 0.348 [9] 0.04 0.21 (10.08/0.12) (10.020/0.018) The preforms were detooled after CVI SiC infiltration. Therefore, the volume of BN could not be measured directly from weight gain. Instead, the volume of BN was estimated from average BN thickness measurements of polished specimens. The volume of SiC was determined from the weight gain after CVI infiltration after subtracting the estimated weight of BN and the known weights of the fibers for the panel preform. The fiber, BN, and CVI SiC densities used were 3.05, 1.5, and 3.2 g/cm3 , respectively. DiCarlo et al. 6 www.ceramics.org/ACT SiC Fiber-Reinforced MI SiC Composites 153