Oxide ceramic fibres

M-H. Berger, Fracture Processes in Oxide Ceramic Fibres, pp. in Fiber Fracture Ed. M. Elices and J. Llorca, Elsevier (2002). 

FRACTURE PROCESSES IN OXIDE CERAMIC FIBRES INTRODUCTION... 

Fracture Processes in Oxide Ceramic Fibres M.-H. Berger... 

Refactory ceramic fibres or special purpose fibres, with the exception of those specified elsewhere in the Approved Supply List (man-made vitreous (silicate) fibres with random orientation with alkaline oxide and alkali earth oxide (Na20 + K2O + CaO + MgO + BaO) content less than or equal to 18% by weight)... 

Reinforcements in the form of continuous fibres, short fibres, whiskers or particles are available commercially. Continuous ceramic fibres are very attractive as reinforcements in high-temperature structural materials. They provide high strength and elastic modulus with high temperature-resistant capability and are free from environmental attack. Ceramic reinforcement materials are divided into oxide and non-oxide categories, listed in Table 3.1. The chemical compositions of some commercially available oxide and non-oxide reinforcements are given in Table 3.2 and Table 3.3. 

Ceramic oxide fibres, both continuous and discontinuous, have been commercially available since the 1970s, and processing and microstructure control are very important in obtaining the desired properties. Among the desirable characteristics in any ceramic fibre for structural applications are ... 

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. 

There are other promising ceramic fibres, e.g. boron carbide and boron nitride. Boron nitride fibre has the same density (2.2 g cm-3) as carbon fibre, but has a greater oxidation resistance and excellent dielectric properties. Boron carbide fibre is a very light and strong material. 

Janes, Neumann and Sethna ° reviewed the general subject of solid lubricant composites in polymers and metals. They pointed out that the reduction in mechanical properties with higher concentrations of solid lubricant can be offset by the use of fibre reinforcement. Glass fibre is probably the most commonly used reinforcing fibre, with carbon fibre as a second choice. Metal and ceramic fibres have been used experimentally to reinforce polymers, but have not apparently been used commercially. To some extent powders such as bronze, lead, silica, alumina, titanium oxide or calcium carbonate can be used to improve compressive modulus, hardness and wear rate. 

M. Schmiicker, P. Mechnich, All-Oxide Ceramic Matrix Composites with Porous Matrices, in W. Krenkel (ed.) "Ceramic Matrix Composites, Fibre-Reinforced Ceramics and their application" Wiley-VCH, Weinheim, 2008, 205-229... 

Hard spicular fibres (glass fibre, ceramic fibres) Abrasives (metal oxides, silicates, carbides)... 

Several workers have proposed new combinations of materials in an attempt to overcome wear. Studies involving polyimides, polyamide-imides, and poly-tetrafluoroethylene-filled polyoxymethylene demonstrated that although wear characteristics were good in dry conditions, the presence of lubricants (blood plasma, water) decreased the wear resistance. Results obtained with reinforcing materials such as carbon fibre and with an aluminium oxide ceramic ball used in conjunction with a polyethylene socket have been presented, Examples of other types of reconstructive surgery involving hard tissue replacement are the use of poly(methyl methacrylate) in chest wall reconstruction and repair of depressed skull fractures, the repair of major crano-orbital defects with the aid of a polyurethane-coated poly(ethylene terephthalate) mesh, and the use of silicone rubber in total finger joint and carpal bone replacement. 

The pyrotechnic paper or heat paper supplies the thermal energy to elevate the thermal battery cell to operating temperatures. The pad consists of a ceramic fibre paper, which acts as a binder/carrier for a slurry of zirconium metal fuel and barium chromate oxidant. The paper is extremely fast burning, making it ideal for a fast activation cell. Because the remaining ash of the heat pad is electrically non-conductive, it is necessary to provide a means for series intercell connection. 

This chapter is concerned with continuous ceramic fibres derived from organosilicon polymers, and does not cover precursors to oxide ceramics. It should be noted that effective reinforcement of ceramic matrices can be achieved with whiskers and certain particulate materials, as well as continuous fibres, but these materials are not usually made from polymer precursors and fall outside the scope of this chapter. Apart from reinforcement of ceramics, continuous ceramic fibres have considerable potential for reinforcement of light alloys when enhanced strength and modulus is required at elevated temperature. There is also much interest in the development of plastic matrix... 

Taniguchi, S., Kadowaki, M., Yasuo, T, Akiyama, Y, Miyake, Y. and Nishio, K. (20(K)), Improvement of thermal cycling characteristics of a planar-type solid oxide fuel cell by using ceramic fibre as sealing material, J. Power... 

Chollon, G. (2000). Oxidation behaviour of ceramic fibres from the Si-C-N-0 system and related snb-systems. Journal of the European Ceramic Society, 20(12), 1959-1974. doi 10.1016/S0955-2219(00)00101-l. 

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