Fibre properties silicon carbide

Additional increase of properties of titanium-based materials is associated with composites. For example, reinforcement due to continuous fibres of silicon carbide (up to 40-wt.%) permits strength and rigidity of such materials to be essentially increased. However, the cost of such composites appears to be prohibitive (about several tens of thousands of USD per 1-kg [19], Moreover, above temperatures of 600 °C an interaction of fibers and matrix is revealed. 

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. 

Nakano K, Kamiya A, Ogawa H, Nishino Y, Fabrication and mechanical properties of carbon fibre reinforced silicon carbide composites, J Ceramic Soc Japan, 100(4), 472-475, 1992. 

Polysilanes. Following the first reports of soluble and processable polysilanes in the late 1970s, these macromolecules have attracted substantial interest from both fundamental and applied perspectives." The backbone of silicon atoms gives rise to unique electronic and optical properties as a result of the delocalisation of a-electrons. Several polysilanes have also been found to function as useful thermal precursors to silicon carbide fibres and these materials have also attracted attention with respect to microlithographic applications and as polymerisation initiators." ... 

Blissett, M.J., Smith, P. A., Yeomans, J.A. (1997), Thermal shock behaviour of unidirectional silicon carbide fibre reinforced calcium aluminosilicate , J. Mater. Sci., 32, 317-325. Blissett, M.J., Smith, P.A., Yeomans, J.A. (1998), Flexural mechanical properties of thermally treated unidirectional and cross-ply Nicalon-reinforced calcium aluminosilicate composites , J. Mater. Sci., 33, 4181 —4190. 

Silicon carbide has attracted considerable interest because of its good mechanical and physical properties and chemical inertness. One of the most important applications of SiC is to produce a matrix reinforced by fibres, forming ceramic-matrix composites. These composite materials exhibit much better fracture toughness than monolithic ceramics. Compared with carbon/carbon composites, fibre-reinforced SiC matrix composites possess superior oxidation resistance and mechanical properties. The Si-C-H-Cl system (e.g. methyltrichlorosilane, CH3SiCl3) has been used for SiC deposition because it is easy to produce stoichiometric SiC deposits. 

Improved stiffness, strength and thermal properties are offered by beta-Ti alloys reinforced with silicon carbide fibres. A high probability exists that these composites will make their way into the design of the actively cooled airframe of the future US NASP X30 spaceplane. 

Silicon carbide Fibres Mechanical properties Microstructure Defects... 

A very tough 177-204 C versatile curing resin with a continuous service temperature range of -59 to 204 C, and short-term up to 232 C, and designed for RTM. Offers excellent compression properties after impact. Suitable for glass, carbon, aramid, silicon carbide and other fibre reinforcement. 

To design the interfacial properties, the fibres can be coated before the composite is produced by applying thin coatings with a thickness between 0.1 pm and 1 pm. A graphite layer of 1 pm thickness on a fibre based on silicon carbide (called Nicalon), for example, can reduce the interfacial shear strength from 400 MPa to 100 MPa [28]. 

To illustrate the dependence of composite performance on the properties of the fibres and matrices, creep data comparisons and creep curve shape analyses have been undertaken for three SiC-matrix products reinforced with either silicon carbide or alumina fibres. These materials were selected to assess the effects of... 

---