Claims
- 1. A method of infusibilizing a preceramic polymer selected from the group consisting of polycarbosilanes, polysilanes and polysilazanes comprising treating the preceramic polymer with gaseous nitrogen dioxide at a temperature in the range of from about room temperature up to about 300.degree. C. for less than about 2 hours to render the preceramic polymer infusible.
- 2. The method of claim 1 wherein the infusibilized preceramic polymer pyrolyzes to a ceramic which contains less than about 10 weight percent oxygen.
- 3. The method of claim 2 wherein the infusibilized preceramic polymer pyrolyzes to a ceramic which contains less than about 7 weight percent oxygen.
- 4. The method of claim 2 wherein the preceramic polymer is in the form of a fiber.
- 5. The method of claim 2 wherein the nitrogen dioxide is present in a concentration of about 0.5 to 25 weight percent diluted in an inert gas.
- 6. The method of claim 4 wherein the nitrogen dioxide is present in a concentration of about 0.5 to 25 weight percent diluted in a inert gas.
- 7. The method of claim 2 wherein the nitrogen dioxide is present in a concentration of about 2 to 10 weight percent diluted in an inert gas.
- 8. The method of claim 2 wherein the time sufficient to render the preceramic polymer infusible is less than about 30 minutes.
- 9. The method of claim 5 wherein the preceramic polymer is a polycarbosilane.
- 10. The method of claim 5 wherein the preceramic polymer is a methylpolysilane.
- 11. The method of claim 5 wherein the preceramic polymer is a polysilazane.
- 12. The method of claim 5 wherein the preceramic polymer is hydridopolysilazane.
- 13. A method of infusibilizing a preceramic fiber selected from the group consisting of polycarbosilanes, polysilanes and polysilazanes on a continuous spinning line comprising treating said preceramic fiber with gaseous nitrogen dioxide at a temperature in the range of from about room temperature up to about 300.degree. C. for less than about 2 hours to render said preceramic polymer infusible as the fiber is continuously processed from spinning through pyrolysis.
- 14. The method of claim 13 wherein the infusibilized preceramic fiber pyrolyzes to a ceramic which contains less than about 10 weight percent oxygen.
- 15. The method of claim 14 wherein the polymer is treated at a temperature in the range of about 50.degree. to about 300.degree. C.
- 16. The method of claim 15 wherein the time sufficient to render the preceramic fiber infusible is less than about 10 seconds.
BACKGROUND OF THE INVENTION
The invention described herein was made in the performance of work uncer NASA Contract No. NAS 3-25641, and is subject to the provisions of Section 305 of the National Aeronautics and Space Act of 1958, as amended (42 U.S.C. 2457).
US Referenced Citations (18)
Foreign Referenced Citations (1)
Number |
Date |
Country |
2236078 |
Mar 1974 |
DEX |
Non-Patent Literature Citations (2)
Entry |
West, 25 Polymer Preprints 4 (1984). |
Noll, "Chemistry and Technology of Silicones" pp. 347-349 (1968). |