Method for making ceramic matrix composites
AssigneeDow Corning Corporation
InventorsDaniel Ralph Petrak, Gary Lee Stark, Gregg Alan Zank
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Abstract
Fiber reinforced ceramic matrix composites are prepared by coating refractory fibers having a interfacial coating thereon with a curable preceramic polymer having a char which contains greater than about 50% sealant oxide atoms followed by forming the coated fibers into the desired shape, curing the coated fibers to form a pre-preg, heating the pre-preg to form a composite and heating the composite in an oxidizing environment to form an in situ sealant oxide coating on the composite. The resultant composites have good oxidation resistance at high temperature as well as good strength and toughness.
Claims20
A method for forming a high strength, oxidation resistant fiber-reinforced ceramic matrix composite which retains a tensile strength of at least 16.5 Ksi after being heated to at least 1100.degree. C. in air, which process comprises:
- (a) coating refractory fibers having an interfacial coating thereon which a preceramic matrix mixture comprising a curable preceramic polymer having a char which contains greater than about 50 weight % sealant oxide atoms;
- (b) forming the coated fibers into the desired shape;
- (c) curing the preceramic matrix mixture to produce a green body;
- (d) heating the green body to a temperature of at least about 1000.degree. C. in an inert atmosphere for a time effective to convert the preceramic polymer to a ceramic and thereby form a ceramic matrix composite;
- and
- (e) heating the ceramic matrix composite to a temperature above 1100.degree. C. in an oxidizing environment to form an in situ coating comprising silica on the surface of the ceramic composite exposed to the environment.
A method of forming a high strength, oxidation resistant 3-dimensional fiber-reinforced ceramic matrix composite which retains a tensile strength of at least 16.5 Ksi after being heated to at least 1100.degree. C. in air, which process comprises:
- (a) forming refractory fibers having an interfacial coating thereon into a preform;
- (b) impregnating the preform with a preceramic matrix mixture comprising a curable preceramic polymer having a char which contains greater than about 50 weight % silicon atoms;
- (c) curing the formed impregnated preform;
- and
- (d) heating the cured impregnated preform of (c) to a temperature of at least about 1000.degree. C. in an inert atmosphere for a time effective to convert the preceramic polymer to a ceramic.
Dependencies are inferred from the claim text.