Method for making high yield-low carbon ceramic via polysilazane

Abstract

A method of making a shaped article and composite therefor which includes of a shaped tool, such as a mold and providing a composite of a quartz fabric disposed within a polysilazane which is moldable at a temperature below the curing temperature of the polysilazane and cured by catalyst. The polysilazane can be optionally filled with particulate material. A compaction pressure is applied to the composite to insure contact of the composite and the tool and prevent loss of less reactive polysilazane components. The composite is then cured to hardness by increasing the temperature applied to the composite at a rate of about 10.degree. C./minute to a temperature of about 150.degree. C. and holding that temperature of about 150.degree. C. up to about 4 hours to provide a cured polymer. The cured composite is removed from the tool. The polymer can then be converted to a preceramic by heating the cured polymer to a temperature sufficiently high in an inert atmosphere or ammonia gas for a sufficient time. The removal of carbon will occur when processed in ammonia The preceramic can then be reprocessed by repeating the above procedure after cooling and reinfiltrating with uncured resin.