Silicon carbide fibre high temperature

An important application of polydimethylsilane is as a source of silicon carbide (SiC) fibres, which are manufactured under the trade-name Nicalon by Nippon Carbon in Japan. Heating in an autoclave under pressure converts polydimethylsilane to spinnable polycarbosilane (-Me2Si-CH2-) with elimination of methane. The spun fibres are then subjected to temperatures of 1200-1400 °C to produce silicon carbide fibres with very high tensile strengths and elastic moduli." As a result of their conductivity, polysilanes have also been used as hole transport layers in electroluminescent devices. In addition, the photoconductivity of polymethylphenylsilane doped with Cgo has been found to be particularly impressive. ... 

Commercially available non-oxide ceramic reinforcements are in three categories continuous, discontinuous, and whiskers. The great breakthrough in the ceramic fibre area has been the concept of pyrolysing polymers under controlled conditions, containing the desired species to produce high-temperature ceramic fibres. Silicon carbide fibre is a major development in the field of ceramic reinforcements. 

The most simple methods for preparation of hafnium carbide and its composites are the follows. The powder of HfO was thermally treated with Mg in molar ratio 5 4 under a CH flow ranging from 800 to 950 °C [4]. The effective high temperature coating for carbon fiber reinforced carbon and carbon fibre reinforced silicon carbide was prepared with use of HfC [5]. For this purpose hafnium carbide layers were obtained in a thermally simulated chemical vapor deposition (CVD) reactor on nonporous substrates by reaction of hafnium tetrachloride, methane and addition of hydrogen (Eq. 10.1) ... 

Ansorge F, Characterisation of carbon fibre/silicon carbide matrix composites, Naslain R, Lamon J, Doumeingts D eds.. High Temperature Ceramic Matrix Composites, Proceedings of 6th European Conference on Composite Materials, European Association for Composite Materials, American Ceramic Soc Inc, Ceramic Society of Japan, Bordeaux, 491-498, 20-24 Sep 1993. 

Xu Y, Cheng L, Zhang L, Yan D, Mechanical properties and microstructural characteristics of carbon fibre reinforced silicon carbide matrix composites by chemical vapour infiltration, Niihara K, Nakano K, Sekino T, Yasuda E eds.. Ceramic Society of Japan, High Temperature Ceramic Matrix Composites III, Proc 3rd Int Conf, Osaka, Sep 6-9 1998, 73-16, Key Eng Mater, Vol 164-165. 

Polycrystalline-alumina-based fibres can at present not compete with silicon-carbide-ba.sed fibres when low creep rates are required. Fibres with higher resistance to creep by dislocation motion could be provided by oxides with high melting point and complex crystal structure, a tendency to order over long distances and the maintenance of this order to high fractions of the melting temperatures (Kelly, 1996). Experimental development of monocrystalline fibres by Czochralski-derived techniques from chrysoberyl... 

One non-oxide fibre that receives attention is the group based on silicon carbide (e.g. Nicalon , Nippon Carbon), which is available as cf tow for use in high temperature rigid composites with either polymer-based resin or metal matrices such as tungsten. 

Short-fibre reinforced metal matrix composites are significantly less expensive than long-fibre reinforced materials and can thus be used in automotive engineering or in sports equipment. For example, short-fibre reinforced aluminium-silicon carbide composites can be used as pistons in diesel engines at elevated temperatures [49]. Golf clubs and bicycle components can also be manufactured from aluminium matrix composites. Frequently, whiskers (see section 6.2.8) are used as short fibres because of their high strength and favourable aspect ratio. 

S. Zhu, M. Mizano, Y. Kagawa, J. Cao, Y. Nagano and H. Kaya, Creep and fatigue behaviour in Hi Nacolon fibre reinforced silicon carbide composites at high temperatures, J. Am. Ceram. Soc. 82, 117 128 (1999). 

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