Patent US5030702A successfully refreshed from Google Patents.
US5030702A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Polysilazanes, processes for their preparation, ceramic materials which contain silicon nitride and can be prepared from them, and preparation thereof
Assignee: Hoechst AG
•
Filing: 1990-03-21
•
Granted: 1991-07-09
•
Expires: 2010-03-21
Abstract
Abstract The invention relates to novel polysilazanes, their preparation, their further processing to ceramic material containing silicon nitride and this material itself. To prepare the polysilazanes, Si,Si'-diorganyl-N-alkyltetrachloro-disilazanes of the formula RSiCl 2 -NR'-SiCl 2 R are reacted with ammonia. The polysilazanes can then be pyrolyzed to ceramic material containing silicon nitride. The polysilazanes according to the invention dissolve in the customary aprotic solvents.
Inventors
- 👤 Tilo Vaahs
- 👤 Hans-Jerg Kleiner
- 👤 Marcellus Feuckert
- 👤 Martin Bruck
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 19:45
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C04B35/589; C08; C08G; C08G77/00; C08G77/60; C08G77/62
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
84 words
A process for the preparation of ceramic material containing silicon nitride, which comprises pyrolyzing a polymeric silazane of the formula ##STR9## in which R, R*, R** and R*** can be identical or different and R, R*, R** and R*** are C 1 -C 4 -alkyl, vinyl or phenyl, R' is C 1 -C 4 -alkyl and x and y denote the molar fractions of the two structural units, x+y being 1 and x being 0.7-0.95 in an inert atmosphere at 800° to 1400° C.
Claim 2
Dependent Claim
84 words
A process for the preparation of ceramic material containing silicon nitride, which comprises pyrolyzing a polymeric silazane of the formula ##STR9## in which R, R*, R** and R*** can be identical or different and R, R*, R** and R*** are C 1 -C 4 -alkyl, vinyl or phenyl, R' is C 1 -C 4 -alkyl and x and y denote the molar fractions of the two structural units, x+y being 1 and x being 0.7-0.95 in an inert atmosphere at 800° to 1400° C.
Claim 3
Dependent Claim
42 words
The process as claimed in claim 1, wherein to produce ceramic fibers containing silicon nitride, the polymeric silazane is first dissolved in an organic solvent, fibers are drawn from this solution and these are pyrolyzed after the solvent has been evaporated off.
Claim 4
Dependent Claim
30 words
The process as claimed in claim 1, wherein to produce a ceramic shaped article containing silicon nitride, the pulverulent polymeric silazane is pressed to a shaped article before the pyrolysis.
Claim 5
Dependent Claim
47 words
The process as claimed in claim 1, wherein to produce a ceramic coating containing silicon nitride, the polymeric silazane is first dissolved in an organic solvent, the coating process is carried out with this solution and the coating is pyrolyzed, after the solvent has been evaporated off.
Claim 6
Dependent Claim
82 words
A process for the production of ceramic fibers containing silicon nitride, which comprises melting a polymeric silazane of the formula ##STR10## in which R, R*, R** and R*** are ethyl and R' is methyl, x and y denote the molar fractions of the two structural units, x+y being 1 and x being 0.7-0.95, drawing fibers from the melt at 60° to 100° C., rendering these non-fusible with air and the pyrolyzing the product at 800° to 1400° C. in an inert atmosphere.
Claim 7
Dependent Claim
82 words
A process for the production of ceramic fibers containing silicon nitride, which comprises melting a polymeric silazane of the formula ##STR10## in which R, R*, R** and R*** are ethyl and R' is methyl, x and y denote the molar fractions of the two structural units, x+y being 1 and x being 0.7-0.95, drawing fibers from the melt at 60° to 100° C., rendering these non-fusible with air and the pyrolyzing the product at 800° to 1400° C. in an inert atmosphere.
Claim 8
Dependent Claim
91 words
A process for the production of a ceramic shaped article containing silicon nitride, which comprises melting a polymeric silazane of the formula ##STR11## in which R, R*, R**, and R*** are ethyl and R' is methyl, x and y denote the molar fractions of the two structural units, x+y being 1 and x being 0.7-0.95, processing the melt by casting, injection molding or extrusion to give a shaped article, rendering this non-fusible with air or NH 3 and then pyrolyzing the product at 800° to 1400° C. in an inert atmosphere.
Claim 9
Dependent Claim
91 words
A process for the production of a ceramic shaped article containing silicon nitride, which comprises melting a polymeric silazane of the formula ##STR11## in which R, R*, R**, and R*** are ethyl and R' is methyl, x and y denote the molar fractions of the two structural units, x+y being 1 and x being 0.7-0.95, processing the melt by casting, injection molding or extrusion to give a shaped article, rendering this non-fusible with air or NH 3 and then pyrolyzing the product at 800° to 1400° C. in an inert atmosphere.
Claim 10
Dependent Claim
16 words
The process as claimed in claim 1, wherein the pyrolysis is carried out at 800°-1200° C.
Claim 11
Dependent Claim
16 words
The process as claimed in claim 1, wherein the pyrolysis is carried out at 1200°-1400° C.
Claim 12
Dependent Claim
15 words
A ceramic material containing silicon nitride, obtainable by the process as claimed in claim 1.
Claim 13
Dependent Claim
91 words
A process for the preparation of ceramic material containing silicon nitride, which comprises pyrolizing a polymeric silizane of the formula ##STR12## in which R, R*, R**, and R*** can be identical or different and R, R*, R** and R*** are C 1 -C 4 -alkyl, vinyl or phenyl, R' is C 1 -C 4 -alkyl and x and y denote the molar fractions of the two structural units, x+y being 1 and x being 0.7-0.95, in an NH 3 or N 2 /H 2 atmosphere at 800° C. to 1400° C.
Claim 14
Dependent Claim
91 words
A process for the preparation of ceramic material containing silicon nitride, which comprises pyrolizing a polymeric silizane of the formula ##STR12## in which R, R*, R**, and R*** can be identical or different and R, R*, R** and R*** are C 1 -C 4 -alkyl, vinyl or phenyl, R' is C 1 -C 4 -alkyl and x and y denote the molar fractions of the two structural units, x+y being 1 and x being 0.7-0.95, in an NH 3 or N 2 /H 2 atmosphere at 800° C. to 1400° C.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-07-08 | 1995-01-07 | 1995-07-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-07-08 | 1999-01-07 | 1999-07-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-07-08 | 2003-01-07 | 2003-07-09 | $7700.00 | Window Closed / Lapsed |