Claims
- 1. A process for the production of an organoborosilicon ceramic prepolymer of the structure: ##STR8## wherein R.sup.1 is selected from alkyl having from 1 to 10 carbon atoms or phenyl, and x is selected from 0, 1, 2 or 3;
- which prepolymer is pyrolyzable to produce a refractory material comprising ceramic compounds of Si, C and B, which process comprises:
- contacting a silicon containing compound of the structure:
- (R.sup.1).sub.x --Si (CH.dbd.CH.sub.2).sub.4-x
- with a boron containing compound selected from H.sub.3 B:BH.sub.3, H.sub.3 B:NH.sub.3, or BH.sub.3 :N(R.sup.2).sub.3 wherein R.sup.2 is selected from methyl, ethyl, propyl, butyl, or phenyl in an inert anhydrous atmosphere at a temperature of between about 90.degree. and 170.degree. C. for between about 0.1 and 120 hr; and
- recovering the ceramic prepolymer.
- 2. The process of claim 1 wherein in the silicon containing compound, x is 0 and the boron containing compound is BH.sub.3 :BH.sub.3.
- 3. The process of claim 1 wherein the silicon containing compound, x is 0, and the boron containing compound is H.sub.3 B:NH.sub.3, with the proviso that when H.sub.3 B:NH.sub.3 is used, nitrogen remains in the organoborosilicon ceramic prepolymer in between about 1.5 and 13 percent by weight.
- 4. The process of claim 1 wherein in the silicon containing compound, R.sup.1 is methyl, x is 2, and the boron containing compound is H.sub.3 B:N(R.sup.2).sub.3.
- 5. The process of claim 1 wherein the molecular weight of the prepolymer, is between about 500 and 100,000 daltons.
- 6. The organic/inorganic ceramic prepolymer produced by the process of claim 1.
- 7. The organic ceramic prepolymer produced by the process of claim 2.
- 8. The organic/inorganic ceramic prepolymer produced by the process of claim 3.
- 9. A process for the production of an organoborosilicon ceramic prepolymer of the structure: ##STR9## wherein R.sup.1 is selected from alyl having from 1 to 10 carbon atoms or phenyl, and x is selected from 0, 1, 2 or 3;
- which prepolymer is pyrolyzable to produce a refractory material comprising ceramic compounds of Si, C and B, which process comprises:
- contacting a silicon containing compound of the structure:
- (R.sup.1).sub.x --Si--(C.tbd.CH).sub.4-x
- with a boron containing compound selected from H.sub.3 B:BH.sub.3, H.sub.3 B:NH.sub.3, or BH.sub.3 :N(R.sup.2).sub.3 wherein R.sup.2 is selected from methyl, ethyl, propyl, butyl, or phenyl in an inert anhydrous atmosphere at a temperature of between about 90.degree. and 170.degree. C. for between about 0.1 and 120 hr; and
- recovering the ceramic prepolymer.
- 10. The process of claim 9 wherein in the silicon containing compound, x is 0 and the boron containing compound is BH.sub.3 :BH.sub.3.
- 11. The process of claim 9 wherein the silicon containing compound, x is 0, and the boron containing compound is H.sub.3 B:NH.sub.3, with the proviso that when H.sub.3 B:NH.sub.3 is used, nitrogen remains in the organoborosilicon ceramic prepolymer in between about 1.5 and 13 percent by weight.
- 12. The process of claim 9 wherein in the silicon containing compound, R.sup.1 is methyl, x is 2, and the boron containing compound is H.sub.3 B:N(R.sup.2).sub.3.
- 13. The process of claim 9 wherein the molecular weight of the prepolymer is between about 500 and 100,000 daltons.
- 14. The organic/inorganic ceramic prepolymer produced by the process of claim 9.
- 15. The organic/inorganic ceramic prepolymer produced by the process of claim 10.
- 16. The organic/inorganic ceramic prepolymer produced by the process of claim 11.
BACKGROUND OF THE INVENTION
The invention disclosed herein was made in the performance of work under a NASA Contract and is subject to public Law 96-517 (35 U.S.C. .sctn.200 et seq.). The contractor has not elected to retain title in this invention.
The present invention relates to the preparation of an organic-inorganic polymer comprising boron-carbon-silicon, the polymer itself and the ceramic produced by the pyrolysis of the polymer.
Ceramics are prepared by pyrolysis of various organosilicon polymers A general discussion of the history of the field is found in K. J. Wynne, et al., Annual Reviews of Materials Science (1984), Vol. 14, p. 297; R. W. Rice, American Ceramic Society Bulletin (1983), Vol. 62, p. 889; and in G. E. Legrow, et al. (1987) American Ceramic Society Bulletin, Vol. 66, p. 363. More recently, M. S. Hsu, et al., in Polymer Preprint (1986), Vol. 27, #2, p. 261, disclose a number of organic silicon-boron polymer compounds that produce refractory materials upon degradation. An organo-silicon polymer containing boron may improve the properties of the polymer and the ceramic product.
It is reported by E. C. Ashby, Journal of the American Chemical Society (1959), Vol. 81, p. 4791 and by M. F. Hawthorne, Journal of Organic Chemistry (1959), Vol. 23, p. 1788, that diborane (H.sub.3 B:BH.sub.3) and a borane amine complex react with organic olefin compounds to form saturated addition products:
R is an organic group in this reference. However, no polymer was synthesized from this reaction
Amine adducts of borane are reported to be useful in the hydroborane reaction. For example M. F. Hawthorne Journal of the Chemical Society (1960), Vol. 82, p. 748; and H. Steinberg, et al. (Ed.) Progress in Boron Chemistry, Vol.1, the MacMillan Company, New York, N.Y., 1964, report the complex trimethylamine-t-butylborane reacts rapidly with olefin near 50.degree. C. to produce t-butyl dialkylboron compounds or heterocyclic boron compounds.
U.S. Patents of interest include J. A. Dupont, et al., U.S. Pat. No. 3,154,520; S. R. Riccitiello, et al., U.S. Pat. No. 4,767,728; S. Yajima, et al., U.S. Pat. No. 4,152,509; and E. N. Peters, U.S. Pat. No. 4,235,987.
All references and patents cited herein are incorporated by reference in their entirety.
None of the above references disclose or suggest the polymer precursors, the polyorganoborosilicon or silicon-boron ceramic polymers of the present invention.
It is highly desirable to have polymer precursors for --Si--B--C-ceramic materials that are formed from readily available and relatively inexpensive starting materials and in high yield. Additional desirable properties include stability at room temperature for prolonged periods of time, and high yield of ceramic material upon pyrolysis. The present invention provides such useful silicon-carbon-boron ceramic materials.
The present invention relates to a process for the production of an organoborosilicon preceramic polymer of the structure: ##STR2## wherein R.sup.1 selected from alkyl having 1 to 10 carbon atoms or phenyl, and x is selected from 0, 1, 2 or 3, which is pyrolyzable to produce a refractory material (comprising inorganic compounds of Si, C and B, which process comprises contacting a silicon containing compound of the structure:
The ceramic silicon-boron-carbon compounds of the present invention are useful in high temperature (e.g., aerospace) applications. The ceramic is useful to infiltrate other ceramic structures to produce a composite having higher temperature and oxidation-resistant properties. The organic preceramic polymer is decomposed in a closed system to deposit particles on a substrate. Alternatively, the organic polymer is shaped into an article form and pyrolyzed to produce the ceramic in article form which has high temperature useful properties, including oxidation resistance.
US Referenced Citations (5)
Non-Patent Literature Citations (9)
| Entry |
| K. J. Wynne et al., Annual Reviews of Materials Science, vol. 14, pp. 297-333, (1984). |
| R. W. Rice, American Ceramic Society Bulletin, vol. 66, p. 363, (1983). |
| M. S. Hsu et al., Polymer Preprint, vol. 27, #2, p. 261, (1986). |
| E. C. Ashby, Journal of the American Chemical Society, vol. 81, p. 4791, (1959). |
| M. F. Hawthorne, J. Org. Chem., (1959), vol. 23, p. 1788. |
| M. F. Hawthorne, J. Amer. Chem. Soc., (1960), vol. 82, p. 748. |
| H. Steinberg et al. (ed), (1964), Progress in Boron Chemistry, The MacMillan Company, New York, N.Y., pp. 298-299. |
| G. E. Legrow et al., American Ceramic Soc. Bulletin, (1987), vol. 66, 32, pp. 363-367. |
| R. J. Brotherton et al. (ed), (1970), Progress in Boron Chemistry, vol. 3, Pergamon Press, New York, N.Y., p. 299. |
Patent Grant
4987201
