# US 5,708,114 A · Crosslinkers for silazane polymers

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- Number: US 5,708,114 A
- Document ID: US5708114A
- Status: Granted
- Kind: A
- Application number: 08/805,397
- Filed: 1997-02-24
- Granted: 1998-01-13
- Earliest claimed: 1996-05-20
- Assignees: Dow Corning Corporation
- Inventors: Thomas Duncan Barnard; Duane Ray Bujalski; Gregg Alan Zank
- Web page: https://patentgrep.com/patent/US5708114A

## CPC

- C04B 41/009: {characterised by the material treated}
- C04B 35/571: obtained from {Si-containing} polymer precursors {or organosilicon monomers}
- C04B 35/589: obtained from {Si-containing} polymer precursors {or organosilicon monomers}
- C04B 35/80: Fibres, filaments, whiskers, platelets, or the like
- C04B 41/5066: {Silicon nitride}
- C04B 41/87: Ceramics
- C08J 5/248: {using pre-treated fibres}
- C08J 5/249: {characterised by the additives used in the prepolymer mixture}
- C08K 5/0025: {Crosslinking or vulcanising agents; including accelerators}
- C08K 5/54: Silicon-containing compounds {(C08K5/0091 takes precedence)}
- C08L 83/16: in which all the silicon atoms are connected by linkages other than oxygen atoms
- C08J 2383/04: Polysiloxanes
- C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)

## Abstract

A method of crosslinking a silazane polymer having Si--H bonds in which the polymer is mixed with a crosslinker selected from alkenyl functional cyclosiloxanes and alkenyl functional cyclosilazanes and a crosslinking promoter and then heated to a temperature sufficient to crosslink the silazane polymer. The mixture of the silazane polymer, crosslinker and promoter is useful in the formation of ceramic matrix composites.

## Claims

### Claim 1

A method of forming a ceramic matrix composite comprising
preparing a mixture comprising a silazane polymer having Si--H bonds, a crosslinker selected from the group consisting of alkenyl functional cyclosiloxanes and alkenyl functional cyclosilazanes and a crosslinking promoter;
impregnating an assembly of fibers with the mixture;
heating the impregnated fibers to a temperature sufficient to crosslink the silazane polymer to produce a pre-preg; and
pyrolyizing the pre-pre at a temperature sufficient to ceramify the pre-preg.

### Claim 2 (depends on 1)

The method of claim 1 wherein the resultant ceramic matrix composite is impregnated and pyrolyzed to form an oxidatively stable ceramic matrix composite.

### Claim 3

A method of densifying a porous ceramic comprising:
preparing a mixture comprising a silazane polymer having Si--H bonds, greater than about 15 wt % of a crosslinker selected from the group consisting of alkenyl functional cyclosiloxanes and alkenyl functional cyclosilazanes and a crosslinking promoter;
impregnating a porous ceramic with the mixture;
heating the impregnated porous ceramic to a temperature sufficient to crosslink the silazane polymer; and
pyrolyzing the porous ceramic containing the cured silazane polymer to a temperature sufficient to ceramify the polymer.

### Claim 4

A solvent free method of densifying a porous ceramic comprising:
preparing a mixture consisting essentially of a silazane polymer having Si--H bonds, greater than about 15 wt % of a crosslinker selected from the group consisting of alkenyl functional cyclosiloxanes and alkenyl functional cyclosilazanes and a crosslinking promoter;
impregnating a porous ceramic with the mixture;
heating the impregnated porous ceramic to a temperature sufficient to crosslink the silazane polymer; and
pyrolyzing the porous ceramic containing the cured silazane polymer to a temperature sufficient to ceramify the polymer.