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Ceramic matrix composite (CMC) integrated with various advanced properties is a promising material in many space projects. In those applications, CMC will be subjected to various extreme environments with temperature range of − 170 to 2000 ∘C as well as space particles. A series of methods have been developed to simulate different stage of severe environment, i.e., launching stage, staying stage and re-entry stage. C/SiC related materials have been investigated by these simulation methods. A lot of useful information obtained by the series of simulation methods have been remarkably enhanced our understanding on the behavior of CMC used for RLV hot structures.

A new protocol for the Cu(OAc)2-mediated cyanation of arenes using benzimidazole as the directing group with 2-(4-methylpiperazin-1-yl)acetonitrile as the cyano source was developed. A series of cyano derivatives were facilely and conveniently obtained in moderate to good yields by using this method. The C–H activation catalytic system was originally applied to the C(sp2)–H cyanation of the aryl/heteroaryl to synthesize 2-(1H-benzo[d]imidazol-2-yl)aryl nitriles. There were 19 new compounds in the synthesized 20 cyanide products. In this reaction, 2-(4-methylpiperazin-1-yl)acetonitrile as the cyano source was originally employed in the C(sp2)–H cyanation of the arenes. In addition, a fluorescent material 5a was obtained by derivative reactions of the obtained cyanide product 3. [ABSTRACT FROM AUTHOR]

A protocol for the Cu(TFA)2-catalyzed (TFA=trifluoroacetic acid) picolinamido-directed C8−H cyanation of naphthalene derivatives with benzoyl cyanide as the cyano source has been developed. A series of 8-cyano-1-(picolinamido)naphthalene derivatives were efficiently obtained in moderate to good yields by using this method. We prepared a total of 22 products, 10 of which have not previously been reported. Benzoyl cyanide was originally employed for the C(sp2)−H cyanation of arenes. The picolinamide moiety served a critical role as the directing group in this cyanation reaction of naphthalenes. [ABSTRACT FROM AUTHOR]

A T300 carbon fiber and a SiC-coated C/SiC composite made from the same fiber were studied in atomic oxygen environment. The carbon fiber shows significant degradation while the erosion rate of SiC-coating of C/SiC is about 50 times lower. Evidence shows that Si is preferentially etched from the SiC surface. And XPS information showed that amorphous carbon and diamond-like carbonare periodically generated on the tested composite surface. Statistical analysis shows that the C/SiC specimens have no significant change in flexural properties after 1-year fluence AO treatment. [ABSTRACT FROM AUTHOR]

In this paper, the 12k T-700 TM Multiaxial-Warp-Knitting-Needle (MWK-N) C/SiC composite and pin were designed and fabricated using the isothermal chemical vapor infiltration (ICVI) method. The composite's microstructure and mechanical properties were examined by subjection to tensile and interlaminar shear tests. Three types of double-shear tests were conducted for C/SiC pins, including shear loading perpendicularly, along, and at 45° off-axial to the lamination. The fracture surface of the tensile and shear failure specimens was observed under scanning electronic microscope (SEM). The relationships between the composite's microstructure, mechanical properties, and damage mechanisms were established. The composite's average tensile strength was σ uts = 68.3 MPa and the average interlaminar shear strength was τ u = 38.7 MPa. For MWK-N-C/SiC pins, the double-shear strength was τ u = 76.5 MPa, 99.7 MPa, and 79.6 MPa for test types I, II, and III, respectively. Compared with MWK-C/SiC pins, the double-shear strength of MWK-N-C/SiC pins all decreased, i.e., 26.7%, 50.8%, and 8% for test types I, II, and III, respectively. The MWK-N-C/SiC composite and pins possessed high interlaminar shear strength and double-shear strength, due to the needled fiber in the thickness direction, low porosity (10-15%), and high composite density (2.0 g/cm 3 ).