Claims
- 1. A process for producing wurtzitic or cubic boron nitride comprising the steps of:
- [A] preparing an intimate mixture of powdered boron oxide, a powdered metal selected from the group consisting of magnesium and aluminum, and a powdered metal azide;
- [B] igniting said mixture and bringing it to a temperature at which self-sustaining combustion occurs;
- [C] shocking said mixture at the end of the combustion thereof, while the reaction products are still at a temperature elevated by the heat from said combustion, with a high pressure wave generating a pressure of at least about 100 kbar on said mixture, thereby forming as a reaction product, wurtzitic or cubic boron nitride and occluded metal oxide.
- 2. The process of claim 1 wherein said mixture in (B) is heated to a temperature of at least about 1800.degree. C.
- 3. The process of claim 1 wherein said occluded metal oxide is MgO and is removed by leaching said n product with HCl.
- 4. The process of claim 1 wherein prior to ignition, said mixture is compacted together.
- 5. The process of claim 1 wherein said mixture of (A) has a particle size ranging from about 10 to about microns.
- 6. The process of claim 1 wherein said powdered boron oxide, powdered metal, and powdered metal azide are initially present in stoichiometric ratios.
- 7. The process of claim 1 wherein said metal azide is sodium azide.
- 8. The process of claim 1 wherein said metal is aluminum.
- 9. The process of claim 1 wherein said metal is magnesium.
- 10. The process of claim 1 wherein said pressure wave is generated by an explosion.
- 11. The process of claim 1 wherein said metal azide is present in excess amounts.
- 12. The process of claim 1 wherein said pressure wave is propagated with a gas gun.
- 13. A process for producing wurtzitic or cubic boron nitride comprising the steps of:
- [A] preparing an intimate mixture of powdered boron oxide, a powdered metal selected from the group consisting of magnesium and aluminum, and a powdered metal azide;
- [B] igniting said mixture and bringing it to a temperature at which self-sustaining combustion occurs;
- [C] shocking said mixture at the end of the combustion thereof, while said mixture is still at a temperature at which self-sustaining combustion occurs with a high pressure wave generating a pressure of at least about 100 kbar on said mixture, thereby forming as a reaction product, wurtzitic or cubic boron nitride and occluded metal oxide.
- 14. The process of claim 13 wherein said mixture in (B) is heated to a temperature of at least about 1800.degree. C.
- 15. The process of claim 13 wherein said occluded metal oxide is MgO and is removed by leaching said reaction product with HCl.
- 16. The process of claim 13 wherein prior to ignition, said mixture is compacted together.
- 17. The process of claim 13 wherein said mixture of (A) has a particle size ranging from about 10 to about 30 microns.
- 18. The process of claim 13 wherein said powdered boron oxide, powdered metal, and powdered metal azide are initially present in stoichiometric ratios.
- 19. The process of claim 13 wherein said metal azide is sodium azide.
- 20. The process of claim 13 wherein said metal is aluminum.
- 21. The process of claim 13 wherein said metal is magnesium.
- 22. The process of claim 13 wherein said pressure wave is generated by an explosion.
- 23. The process of claim 13 wherein said metal azide is present in excess amounts.
- 24. The process of claim 13 wherein said pressure wave is propagated with a gas gun.
Government Interests
The United States Government has rights in this invention pursuant to Contract No. W-7405-ENG-48 between the U.S. Department of Energy and the University of California for the operation of the Lawrence Livermore National Laboratory.
US Referenced Citations (9)
Foreign Referenced Citations (4)
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