University of Pennsylvania

Other

Larry G Sneddon

Jeffrey S Beck

Kai C Su

Gregg A Zank

Paul Joseph Fazen

Anne T Lynch

Mark J Pender

Mario G Mirabelli

Thomas Wideman

A method for making a boron carbide containing ceramic involves pyrolyzing a precursor having one or more monosubstituted decaboranyl groups and at least one substituting group containing carbon. The precursor may be molecular, for example comprising two decaboranyl groups linked by a single substituting group, or polymeric, in which case the decaboranyl groups are part of the pendant group of the polymer while a portion of the substituting group makes up the polymer backbone. In either case, the substituting group may be a hydrocarbon, in which case boron carbide may be formed. Alternatively, the substituting group may contain carbon and another ceramic forming element (i.e., other than boron or carbon), such as silicon, nitrogen, or phosphorous, in which case a composite including boron carbide is formed. The precursors used in the present invention are relatively stable in air, allow access to both boron rich and carbon rich materials, and further allow for the formation of films, fibers, and nanostructured materials more easily than other precursors.

Method for making boron carbide containing ceramics

Direct thermal syntheses in the absence of catalyst, of poly(borazylenes) and of oligomers of borazine with polyhedral boranes, carboranes or heteroboranes are disclosed. The products of these syntheses are precursors to BN or other boron-containing ceramics.

Direct thermal synthesis and ceramic applications of poly(borazylenes)

A method for synthesizing borazine in high yields by the reaction of certain ammonium salts, such as ammonium sulfate, and a borohydride, such as sodium borohydride, in solvent at moderate temperatures (e.g., 120.degree.-140.degree. C.) is disclosed.

Method for synthesis of borazine

Novel poly(B-alkenyl-borazines), such as poly(B-vinyl borazine), are useful as precursors to BN ceramics. The poly alkenylborazines, which may advantageously be soluble and easily processed, are prepared by heat treatment of corresponding B-alkenylborazines, which are themselves novel compounds.

Poly (B-alkenyl-borazine) ceramic precursors

The present invention relates to a method of preparing borazine modified polycarbosilane polymers. The method comprises reacting a polycarbosilane polymer with a material comprising at least borazine ring for a time sufficient to produce the desired polymer. This invention also relates to the novel polymers produced by the above method and the ceramic products derived from heating the novel polymers to greater than about 800.degree. C.

Borazine derivatized polycarbosilane polymers and the ceramics derived

The present invention relates to a method of preparing borazine modified hydridopolysilazane polymers. The method comprises reacting a hydridopolysilazane polymer with a material comprising at least one borazine ring for a time sufficient to produce the desired polymer. This invention also relates to the novel polymers produced by the above method.

Borazine derivatized hydridopolysilazane polymers

Poly(b-alkenyl-borazine) ceramic precursors

Lewis base-borane complexes such as (CH.sub.3).sub.2 S.BHBr.sub.2 are utilized as molecular precursors for the formation of both bulk powders, films and coatings of boron nitride. The complexes are subjected to slow heating under an ammonia atmosphere to displace the base and pyrolyze the resulting complex to BN. Analogous processes may be used to prepare Group IIIA-VA compounds of the formula MM' where M is selected from the group consisting of B, Al, Ga, In, and Tl, and M' is selected from the group consisting of N, P, As, Sb and Bi.

Preparation of group IIIA-VA compounds such as boron nitride, and of

Novel poly(alkenylpentaboranes) such as poly-2-vinylpentaborane are useful as precursors to BN or B.sub.4 C ceramics. The non-crosslinked poly(alkenylpentaboranes), which are soluble in common inert organic solvents, are prepared heat treatment of corresponding alkenylpentaboranes. The non-crosslinked poly(alkenylpentaboranes) are heated under an inert atmosphere to crosslink them, and the crosslinked products are pyrolyzed to yield B.sub.4 C. Alternatively, the non-crosslinked poly(alkenylpentaboranes) are heated in the presence of ammonia to yield a nitrogen-containing polymer which, upon pyrolysis, yields BN.

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Havertown, PA, United States of America

Larry G Sneddon