Reinforced silicon carboxide composite with boron nitride coated ceramic fibers

A fiber reinforced glass composite consisting essentially of

• (a) refractory fibers having a boron nitride coating about 10 to 5000 nm thick;
• (b) a carbon-containing black glass ceramic composition having the empirical formula SiCxOy wherein x ranges from about 0.9 to about 1.6 and y ranges from about 0.7 to about 1.8 and wherein said black glass ceramic composition is the pyrolyzed reaction product of
• (1) a cyclosiloxane monomer having the formula ##STR3## where n is an integer from 3 to 30, R is hydrogen, and R' is an alkene of from 2 to 20 carbon atoms in which one vinyl carbon atom is directly bonded to silicon or
• (2) two or more different cyclosiloxane monomers having the formula of ( 1 ) where for at least one monomer R is hydrogen and R' is an alkyl group having from 1 to 20 carbon atoms and for the other monomers R is an alkene from 2 to about 20 carbon atoms in which one vinyl carbon is directly bonded to silicon and R' is an alkyl group of from 1 to about 20 carbon atoms or
• (3) cyclosiloxane monomers having the formula of (1) where R and R' are moieties indepen.dently selected from hydrogen, an alkene of from 2 to about 20 carbon atoms in which one vinyl carbon atom is directly bonded to silicon, or an alkyl group of from 1 to about 20 carbon atoms and at least some of said monomers contain each of said hydrogen, alkene, and alkyl moieties, said reaction taking place in the presence of an effective amount of hydrosilylation catalyst.