13th International Conference on Fracture June 16–21, 2013, Beijing, China 1 Interlaminar Shear Strength for Three Kinds of Ceramic Matrix Composites at 1173K Jianjie GOU, Chengyu ZHANG, Shengru QIAO, Xuanwei WANG National key Laboratory of Thermostructure Composite Materials, Northwestern Polytechnical University, Xi’an 710072, P. R. China blao@nwpu.edu.cn Abstract: Interlaminar shear strength (ILSS) of a two-dimensional carbon fiber reinforced silicon carbide (2D-C/SiC) composite, two-and-a-half-dimensional carbon fiber-reinforced silicon carbide (2.5D-C/SiC) composite along the warp and weft directions and two-dimensional silicon carbide fiber reinforced silicon carbide (2D-SiC/SiC) composite were investigated by the double-notch shear (DNS) test at 1173K in air. The microstructure and fracture morphologies of the DNS specimens were observed by a scanning electron microscope (SEM) and an optical microscope. Experimental data shows that ILSS of 2.5D-C/SiC along the warp direction is not only lower than that of the weft direction, but also lower than 2D-C/SiC. Besides, ILSS for 2D-SiC/SiC is higher than that of the 2D-C/SiC. The possible reasons are analyzed through SEM images, optical micrographs and results of ILSS at 1173K in air. Finally the fracture mechanism is discussed. Key words：Ceramic matrix composites; ILSS; Fracture morphology 1. Introduction Successful development of Continuous Fiber-reinforced Ceramic Matrix Composites (CFCCs) has led to great improvements to the intrinsic problems of brittleness, low fracture toughness and catastrophic failure of the monolithic ceramic. CFCCs are now used in various high-temperature applications, such as structural materials for aerospace industry, aircraft brakes, burner nozzles and rocket thrusters [1-3]. However, even though CFCCs have shown significant increase of damage tolerance and the ability of resistance to fracture in in-plane area, inherent processing defects or cracks in the matrix-rich interlaminar regions of the CFCCs can cause delamination under shear stress, resulting in some kind of structural failure [4-6]. A number of studies with respect to the shear properties for CFCCs have been reported. In-plane and interlaminar shear strength of a unidirectional SiC fiber-reinforced (BaSr)Al2Si2O8 celsian composite were measured by the double-notch shear (DNS) test method between room temperature and 1473K, the difference in layer architecture and alignment of fiber-rich layers with the shear plane in the interlaminar specimens appeared to be the reason for the lower strength of this composite [7]. Choi et al investigated the interlaminar mechanical properties determined for six
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