Microstructure characterization of in situ grown CNFs reinforced Unidirectional Carbon/Carbon composites

L.L. He
Institute of Metal Research, CAS, CN

Keywords: microstructure, nanofiber, C/C composite

Summary:

Carbon/Carbon composites are composed with carbon fibers and pyrolytic carbon and exhibit excellent high temperature properties such as high strength and stiffness, which made them important candidates for aerospace applications. In situ grown carbon nanofibers on the carbon fibers before deposition of pyrolytic carbon have been proved an efficient method to improve the mechanical properties of C/C composites. In this presentation, microstructures of the C/C composites with in-situ grown CNFs were investigated by high-resolution transmission electron microscopy from the micrometer scale to the nanometer scale. CNFs were densely grown on carbon fibers with no specific direction, their diameters range from 10 nm to100 nm. After chemical vapor infiltration, the roots of high-textured (HT) pyrocarbon surrounded CNFs were embedded in low-textured pyrocarbon, which was deposited on the surface of CFs. Improvements of the mechanical properties of C/Cs may be attributed to this structure feature. However, Lots of pores appeared between HT coated CNFs, and they were supposed to decrease the density of C/C composites.