Silazane polymers from {R'.sub.3 Si}.sub.2 NH and organochlorosilanes
AssigneeDow Corning Corporation
InventorJohn H. Gaul, Jr.
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Abstract
What is disclosed is a process for preparing R'.sub.3 SiNH-- containing silazane polymers by contacting and reacting organochlorosilanes with {R'.sub.3 Si}.sub.2 NH where R' is vinyl, hydrogen, an alkyl radical of 1-3 carbon atoms or the phenyl group. The silazane polymers are useful as chemical intermediates to produce silicon-containing chemical compounds. They are also useful in the formation of silicon carbide-containing ceramic materials.
Claims81
A process of preparing an R'.sub.3 SiNH-- containing silazane polymer which consists of contacting and reacting in an inert, essentially anhydrous, atmosphere, an organochlorosilane or a mixture of organochlorosilanes of the general formula
- R.sub.n SiCl.sub.4-n
- with a disilazane having the general formula
- (R'.sub.3 Si).sub.2 NH
- at a temperature in the range of 25.degree. C. to 300.degree. C. while distilling by-produced volatile products, wherein
- R is vinyl, an alkyl group of 1-3 carbon atoms or phenyl;
- R' is vinyl, hydrogen, an alkyl group of 1-3 carbon atoms or phenyl;
- and
- n has a value of 1 or 2.
A method for preparing a silicon carbide-containing ceramic material which consists of heating a silazane polymer in an inert atmosphere or in a vacuum to at least a temperature of 750.degree. C. until the silazane polymer is converted to silicon carbide ceramic material, which silazane polymer is obtained by a process which consists of contacting and reacting in an inert, essentially anhydrous, atmosphere, an organochlorosilane or a mixture of organochlorosilanes of the general formula
- R.sub.n SiCl.sub.4-n
- with a disilazane having the general formula
- (R'.sub.3 Si).sub.2 NH
- at a temperature in the range of 25.degree. C. to 300.degree. C. while distilling by-produced volatile products, wherein
- R is vinyl, an alkyl group of 1-3 carbon atoms or phenyl;
- R' is vinyl, hydrogen, an alkyl group of 1-3 carbon atoms or phenyl;
- and
- n has a value of 1 or 2.
A method of preparing a silicon carbide-containing ceramic article which consists of
- (A) forming an article of the desired shape from a silazane polymer:
- (B) heating the article formed in (A) in an inert atmosphere or in a vacuum to an elevated temperature of at least 750.degree. C. until the silazane polymer is converted to silicon carbide-containing ceramic, which silazane polymer is obtained by a process which consists of contacting and reacting in an inert, essentially anhydrous, atmosphere, an organochlorosilane or a mixture of organochlorosilanes, wherein the number of diorgano-substituted silicon atoms does not exceed the number of monoorgano-substituted silicon atoms, of the general formula
- R.sub.n SiCl.sub.4-n
- with a disilazane having the general formula
- (R'.sub.3 Si).sub.2 NH
- at a temperature in the range of 125.degree. C. to 300.degree. C. while distilling by-produced volatile products, wherein
- R is vinyl, an alkyl group of 1-3 carbon atoms or phenyl;
- R' is vinyl, hydrogen, an alkyl group of 1-3 carbon atoms or phenyl and
- n has a value of 1 or 2.
A method of preparing an article coated with ceramic which consists of
- (A) coating a substrate with a silazane polymer which silazane polymer is obtained by a process which consists of contacting and reacting in an inert, essentially anhydrous, atmosphere, an organochlorosilane or a mixture of organochlorosilanes of the general formula
- R.sub.n SiCl.sub.4-n
- with a disilazane having the general formula
- (R'.sub.3 Si).sub.2 NH
- at a temperature in the range of 25.degree. C. to 300.degree. C. while distilling by-produced volatile products, wherein
- R is vinyl, an alkyl group of 1-3 carbon atoms or phenyl;
- R' is vinyl, hydrogen, an alkyl group of 1-3 carbon atoms or phenyl and
- n has a value of 1 or 2 and
- (B) heating the coated substrate in an inert atmosphere or in a vacuum, to an elevated temperature of at least 750.degree. C. until the coating is converted to a silicon carbide ceramic material, whereby a silicon carbide-containing ceramic coated article is obtained.
Dependencies are inferred from the claim text.