Preceramic polymers incorporating boron and their application in the sintering of carbide ceramics

An amorphous boron-containing char consisting essentially of boron, carbon, silicon, and nitrogen wherein said boron is substantially homogeneously distributed throughout said char.

A process of producing an amorphous, boron-containing char, said process comprising:

• subjecting a composition comprising a boron-containing silicon, polymer to pyrolysis.

A ceramic fabrication process comprising:

• subjecting a boron-substituted polysilazane, wherein the boron is derived from a borane and is bound to the polysilazane through boron-carbon bonds, to pyrolysis conditions at a temperature and for a time sufficient to produce a ceramic article.

A method for consolidating silicon carbide with a boron-containing amorphous char, said method comprising:

• a) heating a mixture comprising silicon carbide and a boron-substituted silicon polymer under pyrolysis conditions and for a time sufficient to produce an amorphous, boron-containing char which is essentially devoid of elemental boron and boron carbide;
• and
• b) further heating said mixture at a temperature for a time sufficient to produce a sintered, silicon carbide article having a substantially homogeneous distribution of boron throughout said silicon carbide article.