Dow Corning Corporation

William H Atwell

Chandan K Saha

Jonathan Lipowitz

Gregg A Zank

Gary T Burns

Duane R Bujalski

Gary E LeGrow

Eric Jude Joffre

James A Rabe

Kai Su

Donald M Bartos

Gregg Alan Zank

Patrick J Harder

Allan M Alanko

The present invention relates to a method for preparing a ceramic fiber from alkenyl or alkynyl functional resins and to the ceramic fibers produced therefrom. The method comprises (A) forming a fiber from a siloxane resin comprised of R.sup.1.sub.a R.sup.2.sub.b RSiO.sub.(3-a-b)/2 units wherein R is an unsaturated carbon group; each R.sup.1 is selected from the group consisting essentially of an aryl group having from 6 to 10 carbon atoms and functional derivatives thereof; each R.sup.2 is selected from the group consisting essentially of an alkyl group having from 1 to 4 carbon atoms and functional derivatives thereof; a has a value of 0, 1 or 2; b has a value of 0, 1, or 2 with the proviso that a+b &lt;2; (B) curing the fiber by exposing the fiber to high energy radiation to render it non-fusible; and (C) heating the non-fusible fiber in an inert environment to a temperature above about 800.degree. C. to convert it to a ceramic fiber.

Amorphous silicon oxycarbide and crystalline silicon carbide fibers from

Disclosed is a process for the formation of silicon carbide powder in which vaporized polysiloxanes are reacted and pyrolyzed in a single heating step to form the silicon carbide powder. The process is simple and inexpensive and yields powder having desirable characteristics.

Process for preparing silicon carbide powder from vaporized polysiloxanes

The preparation of porous ceramic bodies by sintering certain curable organopolysiloxanes filled with silicon carbide powders. This process is advantageous in that the green bodies have relative high strengths and thus can be easily handled and, if desired, machined before sintering.

Porous silicon carbide ceramics using filled polysiloxanes

A process for the preparation of substantially polycrystalline silicon carbide fibers are provided. The fibers may be fabricated to have a small diameter and are thermally stable at high temperature. The process is carried out by initially forming fibers from a preceramic polymeric precursor comprising phenyl-containing polyorganosiloxane resins. The fibers are then infusibilized to render them nonmelting followed by a pyrolysis step in which the fibers are heated to a temperature in excess of 1600.degree. C. in a nonoxidizing atmosphere to form substantially polycrystalline silicon carbide fibers. The substantially polycrystalline silicon carbide fibers which are formed have at least 75% crystallinity and have a density of at least about 2.9 gm/cm.sup.3. The polymeric precursor or the fibers contain, or have incorporated therein, at least about 0.2 % by weight boron. This incorporation of boron may be accomplished either prior to or during formation of the fibers or during at least one of the infusibilizing or pyrolyzing steps of the process.

Preparation of substantially polycrystalline silicon carbide fibers from

The preparation of highly densified ceramic bodies by the sintering of certain organopolysiloxanes filled with silicon carbide powders, and metal-containing sintering aids is described. Such highly densified ceramic bodies can be prepared by either a pressureless sintering process or a hot press sintering process. The compositions of this invention can be formed into desired shapes and then sintered to form ceramic, shaped bodies with high densities. One advantage of the present invention is that the green bodies have relative high strengths and thus can be easily handles and, if desired, machined before sintered. The organopolysiloxanes useful in this invention must yield a ceramic char which contains free or excess carbon in addition to carbon in the form of silicon carbide upon pyrolysis to elevated temperatures.

Highly densified bodies from organopolysiloxanes filled with silicon

The preparation of highly densified ceramic bodies by sintering certain curable organopolysiloxanes filled with silicon carbide powders, metal-containing sintering aids, and organopolysiloxane curing agents described. Such highly densified ceramic bodies can be prepared by either a pressure-less or a hot press sintering process. The compositions of this invention can be formed into desired shapes and then sintered to form ceramic, shaped bodies with high densities. One advantage of the present invention is that the green bodies have relative high strengths and thus can be easily handled and, if desired, machined before sintering. The curable organopolysiloxanes useful in this invention must yield a ceramic char which contains free or excess carbon in addition to carbon in the form of silicon carbide upon pyrolysis to elevated temperatures.

Curable organopolysiloxanes filled with silicon carbide powders and

A novel mixed binder system for agglomerates is disclosed. The agglomerates are suitable for use in the production of metals and alloys in a carbothermic reduction process such as the production of silicon in a direct arc furnace by the carbothermic reduction of silica. The agglomerates prepared using this mixture binder system have high physical strength over a wide temperature range. The mixed binder system consists essentially of a primary binder selected from the group consisting of coal tar pitch, asphalt, and petroleum pitch and a secondary binder selected from the group consisting of lignosulfonate salts, carbohydrates, and silicates.

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Midland, MI, United States of America

William H Atwell