13th International Conference on Fracture June 16–21, 2013, Beijing, China 2 different CFCCs at ambient temperature and observed the degradation of interlaminar shear strength (ILSS) with decreasing shear stress rate, containing SiC fiber-reinforced SiC matrix composites, SiC fiber-reinforced glass ceramic composites and carbon fiber-reinforced SiC matrix composites [8,9]. Investigation of the life limiting behavior of the melt-infiltrated Hi-Nic SiC/SiC subjected to interlaminar shear was made at 1589K in air under stress rupture loading [10]. M.B. Ruggles-Wrenn and P.D. Laffey investigated the creep behavior of the Nextel™720/alumina (N720/A) composite in interlaminar shear loading at 1473K in air environments [11]. In our previous work, ILSS of 2D-C/SiC at elevated temperature was investigated in air [12]. Nevertheless, a comparison of several kinds of ceramic matrix composites on ILSS in the same condition is still very limited up to now, especially at elevated temperature. Since 2D-C/SiC, 2.5D-C/SiC and 2D-SiC/SiC are commonly used at high temperature, so a detailed investigation and comparison of the shear properties of these composites at elevated temperature appears to be necessary. The objective of this work was to compare the shear behaviors of 2D-C/SiC, 2.5D-C/SiC and 2D-SiC/SiC. Double-notch shear (DNS) test method was specified to determine ILSS of ceramic matrix composites at elevated temperature by American Society for Testing and Materials (ASTM) standard (C-1425-05) [13]. ILSS of the mentioned ceramic matrix composites was determined by DNS at 1173K in air. An analysis of material damage and the failure characteristics with respect to different fibers and woven structures was discussed in the text. 2. Experimental 2.1 Materials and Specimens The 2D-C/SiC,2.5D-C/SiC and 2D-SiC/SiC composites used in this study were fabricated by chemical vapor infiltration (CVI) of SiC into preforms. Fibrous preforms for 2D-C/SiC and 2D-SiC/SiC are plain weaving structure, while fibrous preform for 2.5D-C/SiC is shown in Fig.1. The fibers were coated with pyrocarbon (PyC) with thickness of 200 nm before infiltration of SiC matrix. Residual porosity is sealed by depositing on the external surface of the specimens a suitable coating at the end of the process. The parameters of tested composites are listed in table 1. Figure 1. Schematic diagram of fiber perform for 2.5D-C/SiC composite
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