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US 4,298,559 AGranted
High yield silicon carbide from alkylated or arylated pre-ceramic polymers
AssigneeDow Corning Corporation
InventorsRonald H. Baney, John H. Gaul, Jr.
Life of this patent
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Abstract
Pre-polymers which are alkylated or arylated methylpolysilanes are useful for the preparation of silicon carbide ceramic materials. The pre-polymers exhibit ease of handling and their use to obtain silicon carbide ceramic materials results in high yields.
Claims11
A method of preparing a polysilane having the average formula
- {(CH.sub.3).sub.2 Si}{CH.sub.3 Si} (I)
- in which polysilane there is from 0 to 60 mole percent (CH.sub.3).sub.2 Si.dbd.units and 40 to 100 mole percent CH.sub.3 Si.tbd.units, wherein there is also bonded to the silicon atoms other silicon atoms and additional alkyl radicals of 1 to 4 carbon atoms or phenyl, which method consists of
- (A) reacting under anhydrous conditions, a polysilane which is a solid at 25.degree. C. having the average unit formula
- {(CH.sub.3).sub.2 Si}{CH.sub.3 Si} (II)
- in which there is from 0 to 60 mole percent (CH.sub.3).sub.2 Si.dbd.units and 40 to 100 mole percent CH.sub.3 Si.tbd.units, wherein the remaining bonds on the silicon atoms are attached to either another silicon atom, a chlorine atom or a bromine atom such that the polysilane contains from 10-38 weight percent, based on the weight of the polysilane, of hydrolyzable chlorine of 21-58 weight percent based on the weight of the polysilane of hydrolyzable bromine, with an alkyl or aryl Grignard reagent having the general formula RMgX where X is a halogen and R is an alkyl group of 1 to 4 carbon atoms or phenyl at a temperature of from 0.degree. to 120.degree. C. for a period of from 1 to 48 hours, in a suitable solvent, and
- (B) thereafter recovering the polysilane (I).
3 more elements
A composition of matter consisting essentially of a polysilane which is a solid at room temperature having the average unit formula
- {(CH.sub.3).sub.2 Si}{CH.sub.3 Si}
- in which polysilane there is from 0 to 60 mole percent (CH.sub.3).sub.2 Si.dbd.units and 40 to 100 mole percent CH.sub.3 Si.tbd.units, wherein there is also bonded to the silicon atoms other silicon atoms and additional alkyl radicals of 1 to 4 carbon atoms or phenyl.
A method of preparing silicon carbide ceramic material which consists of heating to at least 1200.degree. C. a polysilane having the average unit formula
- {(CH.sub.3).sub.2 Si}{CH.sub.3 Si}
- in which polysilane there is from 0 to 60 mole percent (CH.sub.3).sub.2 Si.dbd.units and 40 to 100 mole percent CH.sub.3 Si.tbd.units wherein there is also bonded to the silicon atoms other silicon atoms and additional alkyl radicals of 1 to 4 carbon atoms or phenyl.
A method of preparing a silicon carbide-containing ceramic article which consists of
- (A) forming an article of the desired shape from a polysilane having the average formula
- {(CH.sub.3).sub.2 Si}{CH.sub.3 Si}
- in which polysilane there is from 0 to 60 mole percent (CH.sub.3).sub.2 Si.dbd.units and 40 to 100 mole percent CH.sub.3 Si.tbd.units, wherein there is also bonded to the silicon atoms other silicon atoms and additional alkyl radicals of 1 to 4 carbon atoms or phenyl;
- and
- (B) heating the article formed in (A) in an inert atmosphere or in a vacuum to an elevated temperature in the range of 1200.degree. C. to 1600.degree. C. until the polysilane is converted to silicon carbide-containing ceramic.
2 more elements
A method of preparing a filled ceramic article which consists of
- (A) mixing a polysilane with at least one conventional ceramic filler which polysilane has the average formula
- {(CH.sub.3).sub.2 Si}{CH.sub.3 Si}
- in which polysilane there is from 0 to 60 mole percent (CH.sub.3).sub.2 Si.dbd.units and 40 to 100 mole percent CH.sub.3 Si.tbd.units, wherein there is also bonded to the silicon atoms other silicon atoms and additional alkyl radicals of 1 to 4 carbon atoms or phenyl;
- (B) forming an article of the desired shape from the mixture of polysilane and fillers and,
- (C) heating the article formed in (B) in an inert atmosphere or in a vacuum to an elevated temperature in the range of 1200.degree. C. to 1600.degree. C. until the polysilane is converted to a silicon carbide-containing ceramic.
2 more elements
A method of preparing an article coated with ceramic which consists of
- (A) mixing a polysilane with at least one conventional ceramic filler which polysilane has the average unit formula
- {(CH.sub.3).sub.2 Si}{CH.sub.3 Si}
- in which polysilane there is from 0 to 60 mole percent (CH.sub.3).sub.2 Si.dbd.units and 40 to 100 mole percent CH.sub.3 Si.tbd.units, wherein there is also bonded to the silicon atoms other silicon atoms and additional alkyl radicals of 1 to 4 carbon atoms or phenyl;
- (B) coating a substrate with the mixture of polysilane and fillers and,
- (C) heating the coated substrate in an inert atmosphere or in a vacuum to an elevated temperature in the range of 1200.degree. C. to 1600.degree. C. until the coating is converted to a silicon carbide ceramic material whereby a silicon carbide-containing ceramic coated article is obtained.
2 more elements
Dependencies are inferred from the claim text.