Hydridosiloxanes as precursors to ceramic products
First Claim
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1. A method of preparing a coating of a silicious ceramic material on a substrate, which comprises:
- (a) providing a hydridosiloxane polymer containing one or more Si-H bonds per mer unit;
(b) reacting said hydridosiloxane polymer with a hydroxyl-containing compound of the formula R'"'"'--OH, wherein R'"'"' is hydrogen, C1 -C10 alkyl, or aryl of 1-2 rings, and may be substituted with hydroxyl, lower alkyl, lower alkoxy, halogeno, silyl, or amino groups, or combinations thereof, in an inert atmosphere in the presence of a catalyst effective to activate Si--H bonds, to provide a ceramic precursor in which hydrogen atoms in the hydridosiloxane polymer have been replaced by OR'"'"' moieties;
(c) coating a substrate with said ceramic precursor; and
(d) pyrolyzing said ceramic precursor on said substrate at a temperature of at least about 500°
C. to provide a coating of said silicious ceramic material.
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Abstract
A method is provided for preparing preceramic polymers and and silicious ceramic materials which derive therefrom. The preceramic polymers are polysiloxanes which are synthesized by catalytically activating Si--H bonds in a hydridosiloxane starting material and replacing the activated hydrogen atoms with non-hydrogen substituents. These preceramic polysiloxanes are pyrolyzed in a selected atmosphere to give the desired ceramic product. Ceramic products which may be prepared by this technique include silica, silicon oxynitride, silicon carbide, and metal silicates.
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Citations
32 Claims
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1. A method of preparing a coating of a silicious ceramic material on a substrate, which comprises:
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(a) providing a hydridosiloxane polymer containing one or more Si-H bonds per mer unit; (b) reacting said hydridosiloxane polymer with a hydroxyl-containing compound of the formula R'"'"'--OH, wherein R'"'"' is hydrogen, C1 -C10 alkyl, or aryl of 1-2 rings, and may be substituted with hydroxyl, lower alkyl, lower alkoxy, halogeno, silyl, or amino groups, or combinations thereof, in an inert atmosphere in the presence of a catalyst effective to activate Si--H bonds, to provide a ceramic precursor in which hydrogen atoms in the hydridosiloxane polymer have been replaced by OR'"'"' moieties; (c) coating a substrate with said ceramic precursor; and (d) pyrolyzing said ceramic precursor on said substrate at a temperature of at least about 500°
C. to provide a coating of said silicious ceramic material. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11)
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2. A method of preparing a coating of a silicious ceramic material on a substrate, which comprises:
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(a) providing a hydridosiloxane polymer containing one or more Si--H bonds per mer unit; (b) introducing carbon-containing moieties into said polymer by reaction with a compound containing an unsaturated carbon-carbon bond, in the presence of a catalyst effective to activate Si--H bonds, to give a ceramic precursor in which hydrogen atoms in the hydridosiloxane polymer have been replaced by carbon-containing moieties; (c) coating a substrate with said ceramic precursor; and (d) pyrolyzing said ceramic precursor on said substrate at a temperature of at least about 500°
C. to provide a coating of said silicious ceramic material. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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3. A method of preparing a coating of a silicious, nitrogen-containing ceramic material on a substrate, which comprises:
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(a) providing a hydridosiloxane polymer containing one or more Si--H bonds per mer unit; (b) introducing nitrogen-containing moieties into said polymer by reaction with a compound NHR"2 wherein the R" are independently selected from hydrogen, lower alkyl, sily, and aryl of 1-2 rings, in the presence of a catalyst effective to activate Si--H bonds, to give a ceramic precursor in which hydrogen atoms in the hydridosiloxane polymer have been replaced with nitrogen-containing moieties; (c) coating a substrate with said ceramic precursor; and (d) pyrolyzing said ceramic precursor on said substrate at a temperature of at least about 500°
C. to provide a coating of said silicious, nitrogen-containing ceramic material. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25)
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4. A method of preparing a coating of a silicious, metal-containing ceramic material on a substrate, which comprises:
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(a) providing a hydridosiloxane polymer containing one or more Si--H bonds per mer unit; (b) reacting said hydridosiloxane polymer with a compound selected from the group consisting of MLa and M--OH, wherein M is a metal atom, L is an organic ligand associated therewith, and a represents the molar ratio L--M in said complex, in the presence of a catalyst effective to activate Si--H bonds, to provide a ceramic precursor in which said activated Si--H bonds have been replaced by Si--M bonds; (c) coating a substrate with said ceramic precursor; and (d) pyrolyzing said ceramic precursor on said substrate at a temperature of at least about 500°
C. to provide a coating of said silicious, metal-containing ceramic material. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32)
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Specification