科研之友
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摘要
The effect of the pyrolytic carbon(PyC) interface thickness on the heat-stability of CansasⅡ SiCf/SiC composites under Ar up to 1 500 ℃ was studied in detail. After the heat treatment at 1 500 ℃ for 50 h, the interface bonding strength of the thin interface(about 200 nm) decreases from 74.4 to 20.1 MPa(73.0%), while that of the thick interface(about 2 μm) declines from 7.3 to 3.2 MPa(52.7%). At the same time,the decline fraction of strength of the composites with the thin interface is 12.1%, less than that with the thick interface(42.0%). The fiber strength also decreases after heat treatment, which may be due to the significant growth of β-SiC grains and critical defects. The different heat-stability of the interface with the thin and thick thickness might be related to the inconsistency of the degree of the graphitization of PyC. Compared with the composites with the thick interface, the composites with the thin interface remained higher tensile strength after heat treatment due to the better interface bonding strength. The interface with strong bonding strength could protect the fiber by postponing the decomposition of amorphous phases SiCxOy and hindering the generation of fiber defects.
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