Preparation of silicon carbide ceramics from the modification of

Details Preparation of silicon carbide ceramics from the modification of Preparation of silicon carbide ceramics from the modification of

1991-08-29

1993-04-20

Marquis, Melvyn I.

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Compositions to be polymerized by wave energy wherein said...

522 91, 522172, 528 14, 528 17, 528 19, 528 25, 528 31, 525474, 525475, C08J 328

Patent

active

052043800

ABSTRACT:
A method of forming modified preceramic polymers comprising mixing organopolysilanes having a plurality of Si--H functional groups with an effective amount of a metallocene compound, and allowing the mixture to undergo a dehydrogenative reaction is disclosed. Pyrolysis of the modified polymer provides in high yields ceramic residues that approach stoichiometric SiC in composition. Preferably the organopolysilane starting material contains a plurality of tertiary Si--H bonds and has the general formula of [(RSiH).sub.x (RSi).sub.y ].sub.n where the sum of the coefficients x and y equal 1, n is an integer greater than 1, R is a lower alkyl group having from 1 to about 8 carbon atoms, a substituted or unsubstituted lower alkenyl group having from 2 to about 8 carbon atoms, a cycloalkyl group having from 3 to about 10 carbon atoms, substituted or unsubstituted aryl group having from 6 to about 10 carbon atoms. More preferably R is a lower alkyl group having from 1 to about 8 carbon atoms, and still more preferably R is methyl so that the molar ratio of carbon to silicon of the polymer is about 1. The organopolysilanes can be prepared from silyl halides by alkali metal condensation reactions.

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