| abstract |
The present invention relates to preceramic polymers incorporating boron and their application in the sintering of SiC ceramics. The present invention is also directed to a process for preparing a boron-substituted polysilazane which involves preparing a silazane ammonolysis product by reacting ammonia with a halogenated silicon compound selected from the group consisting of RSiX 3 , RR'SiX 2 , RR'R"SiX, SiX 4 and mixtures thereof, wherein X is selected from the group consisting of Cl, Br and I; and R, R' and R" are the same or different and are selected from the group consisting of H, substituted or unsubstituted 1-6 carbon alkyl groups, aryl groups, 2-6 carbon alkenyl groups and 2-6 carbon alkynyl groups, wherein at least one of the halogenated silicon compounds may comprise at least one member selected from the group consisting of alkenyl groups and alkynyl groups; and reacting the silazane ammonolysis product with a borane containing at least one B--H group per molecule under conditions and for a time sufficient to form a boron-substituted polysilazane containing boron-carbon bonds. |