Nanotech 2011

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

Y.Q. Liu, X.F. Lu, P. Xiao, L.L. He
Institute of Metal Research, CAS, CN

Keywords: microstrucuture, carbon nanofiber, C/C composite

Abstract:

Carbon/Carbon composites (C/Cs) which are composed with carbon fibers and pyrolytic carbon exhibit excellent high temperature properties such as high strength and stiffness, which made them important candidates for aerospace applications. In situ grown carbon nanofibers (CNFs) on the carbon fibers have been proved an efficient method to improve the mechanical properties of C/C composites. However, most of microstructure characterization was carried out by polarized light microscopy and SEM observation. In this presentation, CNFs were in situ grown on the carbon fibers (by CVD) and then made into unidirectional C/C composites (by CVI) process. Microstructures of the CNFs were investigated by HRTEM on the nanometer scale. CNFs were densely grown on carbon fibers with no specific direction, their diameters range from 10 nm to100 nm. Ni catalysts remained at the top of CNFs, which indicate CNFs were grown by top-grown mechanism. After CVI processing, 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.
 

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