Fabrication methods polymer pyrolysis

The conventional industrial method for the synthesis of a-silicon carbide is to heat silica (sand) with coke in an electric furnace at 2,000-2,500 °C. However, because of the high melting point of the product, it is difficult to fabricate by sintering or melt techniques. Thus, the discovery of a lower temperature fabrication and synthesis route to silicon carbide by Yajima and coworkers in 197526,27 proved to be an important technological breakthrough. This is a preceramic polymer pyrolysis route that has been developed commercially for the production of ceramic fibers. 

Quantitative DTA methods for untreated cotton and fabric treated with P- and N-containing flame retardants were suitable for determining the efficiency of FRs and provided data that correlated with oxygen index values [184], Childress etal. [185] described DTA, DSC and TG studies on brominated phosphite and phosphate flame refardants. Nara et al. [186] have studied pyrolysis of tetrabrominated epoxy resin and its Are retardant mechanism. Pyrolysis of DER 542 (brominated epoxy resin) and Epikote 1001 (non-brominated epoxy resin) was investigated by DTA en TG. Bhatnagar et al. [187] have reviewed DTA and DSC studies on flame retardant polymers. Carroll-Porczynski [188] described the applications of simultaneous TG and DTA and DTA/MS analysis for predicting the flame retar-dancy of composite textile fabrics and polymers. The use of DTA to identify mineral flllers in rubber formulations is as old as the technique itself [189],... 

As observed by D. Johnson and J. Stiegler, "Polymer-precursor routes lor fabricating ceramics offer one potential means or producing reliable, cost-effective ceramics. Pyrolysis of polymeric metalloorganic compounds can be used to produce a wide variety of ceramic materials." Silicon carbide and silicon oxycarbide fibers have been produced and sol gel methods have been used In prepare line oxide ceramic powders, such as spherical alumina, as well as porous and fully dense monolithic forms. 

Fabrication routes in which a solution of metal compounds is converted into a solid body are sometimes referred to as liquid precursor methods. The sol-gel process has attracted considerable interest since the mid-1970s and forms the most important liquid precursor route for the production of simple or complex oxides. The pyrolysis of suitable polymers to produce ceramics (mainly nonoxides such as SiC and Si3N4) has attracted a fair degree of interest in the past 20 years. It is an important route for the production of SiC fibers. 

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