International ournal of Applied Ceramic Technolog-Nozawa and Tanigawa Vol.7,No.3,2010 Table I. List of SiC/SiC Composites Tested NITE-Thick-Coat NITE-Thin-Coat PIP-Coat Typic microstructure Fiber Tyranno-SA3 Tyranno-SA3 Tyranno-SA3 Architecture UD Fiber volume fraction ~045 ~0.4 0.3 F/M interface 250nm Pyc None 150nm Pyc NITE-SIC NITE-SiC PIP-SiC Density 296g/cm3 319gm3212gcm3 Porosity 0.05 0.02 ~0.20 Proportional Limit 136 MPa(Tensile)204 MPa(Tensile)62 MPa(Tensile) Stress(PLS) Fracture Strength 146 MPa(Tensile) 674 MPa(Bend) 204 MPa(Tensile) 249 MPa(Tensile Elastic Modulus 336 GPa(Tensile) 27 GPa(Bend) 410 GPa(Tensile)45 GPa(Tensile) dles. This oxide phase, however, would not significantly Single-Edge Notched Bend Test(SENB) mpact test results at room temperature. For comparison, a two-dimensional (eight-harness) accumulation ehavior was evaluated by satin-woven SiC/SiC composite was fabricated by the the SENB technique. Various size st polymer impregnation and pyrolysis(PIP)method (Ube different initial notch depth(ao) were applied ("SENB- Industries, Ube, Japan)(hereafter"PIP-Coat"). Tyr- 1-4"in Fig. 1). Note that the width(W) to length(Lo) annoSA third-grade SiC fibers were applied. A ratio was fixed for all specimen types. For comparison, 100-nm-thick CVD-SiC and a subsequent x 150- unnotched bend specimens with a size of nm-thick PyC coating were formed on the fiber surface. 20 mm x 4 mm x 1.5 mm were tested. The number of This PIP process produces the SiC matrix of stoichio- test specimens is also listed in the table in Fig. 1. The metric composition(C/Si a 1)using a blend polymer fiber longitudinal direction for both specimen types of polycarbosilane and polymethylsilane. However, set perpendicular to the loading direction. Test coupons mall pores were distributed in the PIP-SiC matrix as including an artificial straight notch were machined shown in Table I, resulting in a comparably lower den- from the composite plate by a diamond saw with blade sity of x2. 1 g/cm. Details of the piP process are de thickness of <0.5 mm. The specimen surfaces were scribed in nozawa et al. I7 then polished using a standard metallographic techdles. This oxide phase, however, would not significantly impact test results at room temperature. For comparison, a two-dimensional (eight-harness) satin-woven SiC/SiC composite was fabricated by the polymer impregnation and pyrolysis (PIP) method (Ube Industries, Ube, Japan) (hereafter ‘‘PIP-Coat’’). Tyr￾annot-SA third-grade SiC fibers were applied. A B100-nm-thick CVD-SiC and a subsequent B150- nm-thick PyC coating were formed on the fiber surface. This PIP process produces the SiC matrix of stoichio￾metric composition (C/Si 1) using a blend polymer of polycarbosilane and polymethylsilane. However, small pores were distributed in the PIP–SiC matrix as shown in Table I, resulting in a comparably lower den￾sity of B2.1 g/cm3 . Details of the PIP process are de￾scribed in Nozawa et al.17 Single-Edge Notched Bend Test (SENB) Damage accumulation behavior was evaluated by the SENB technique. Various size specimens with a different initial notch depth (a0) were applied (‘‘SENB- 1–4’’ in Fig. 1). Note that the width (W) to length (L0) ratio was fixed for all specimen types. For comparison, unnotched bend specimens with a size of 20 mm 4 mm 1.5 mm were tested. The number of test specimens is also listed in the table in Fig. 1. The fiber longitudinal direction for both specimen types was set perpendicular to the loading direction. Test coupons including an artificial straight notch were machined from the composite plate by a diamond saw with blade thickness of o0.5 mm. The specimen surfaces were then polished using a standard metallographic technique Table I. List of SiC/SiC Composites Tested 306 International Journal of Applied Ceramic Technology—Nozawa and Tanigawa Vol. 7, No. 3, 2010