Commercial applications silicon fibers

The facile formation of ceramic materials from molecules has undoubtedly been one of the si ificant contributions made by chemistry to materials science (7). However, it is desirable not only to produce the ceramic per se but also to do so in a specific form, for example a fiber. Therefore, one of the key requirements for any ceramic precursor should be its processability. For this reason, there has been continued research effort aimed at the design of precursors with physical properties suitable for processing prior to pyrolysis. Two examples with sigr cant commercial application are polyacrylonitrile and polyorganosilanes, both of which may be spun into fibers, and upon pyrolysis allow for the manufacture of carbon-graphite (2) and silicon carbide (5) fibers, respectively. Despite much effort, the extension of this polymer-type precursor strategy to other ceramic systems has only met with limited success. 

Manufacture of P-Silicon Carbide. A commercially utilized application of polysilanes is the conversion of some homopolymers and copolymers to silicon carbide (130). For example, polydimethylsilane is converted to the ceramic in a series of thermal processing steps. Silicon carbide fibers is commercialized by the Nippon Carbon Co. under the trade name Nicalon (see Refractory FIBERS). 

Commercial chemical fibers are combustible in nature, and improved FR properties must be considered in actual application. Most FR additives contain bromine (Br), chlorine (Cl), phosphorus (P), antimony, or aluminum. Among them, commonly used additives are additive brominated hydrocarbons and reactive brominated hydrocarbons, nonhalogenated phosphate esters, halogenated phosphate esters, trioxide antimony oxide, pentoxide antimony oxide and sodium derivatives, chlorinated hydrocarbons like chlorinated paraffin, and chlorinated cycloaUphatics. Others include chlorinated or brominated compounds, fluorinated compounds, magnesium carbonate, magnesium hydroxide, melamine, molybdenum compounds, silicone polymer, and zinc borate. Sometimes, polymers are chemically modified, and N, P, Cl, fluorine (F), silicon (Si), and Br elements can be introduced into the polymer main chain [49]. 

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