Development of novel carbon-based fibers with remarkable oxidation resistance

Reference Presenter Authors
18-007 Luiz Fernando Belchior Ribeiro Ribeiro, L.F.(Federal University of Santa Catarina); Motz, G.(Universität Bayreuth); Bernard, S.(University of Limoges); Hotza, D.(Universidade Federal de Santa Catarina); MACHADO, R.A.(Universidade Federal de Santa Catarina); Carbon fibers (CFs) are currently the most important reinforcement component used for high-performance composites, representing a key material for the modern economy. The biggest drawback of CFs is, however, their insufficient oxidation stability at temperatures as low as 400°C. In this work, we proposed the modification of polyacrylonitrile (PAN), the most widely used carbon precursor, with a commercially available oligosilazanes, as a precursor for SiCN ceramics, which are well known to provide a remarkable resistance to oxidation (>1300°C). To improve the interaction of both educts (acrylonitrile and oligosilazanes) and to avoid phase separation, the in-situ free-radical polymerization of acrylonitrile in the presence of the oligosilazane was performed in order to obtain a hybrid precursor instead of a simple mixture. A selected hybrid polymer composition was used to process fibers via the dry spinning process to investigate the pyrolysis behavior, the phase formation in dependency on the temperature, and the oxidation stability. The thermal treatment converts the hybrid polymer in an amorphous C/Si3N4 nanocomposite, confirmed by NMR, XRD and TEM measurements. Despite the high carbon content, the amorphous C/Si3N4 material possesses a remarkable oxidation resistance (up to 800°C). The homogeneously distributed ceramic phase within the carbon matrix is responsible for the extraordinary intrinsic oxidation stability of this new type of carbon-based fiber.
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