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US 5,398,639 AGranted
Solid state conversion of hexagonal to cubic-like boron nitride
AssigneeGeneral Motors Corporation
InventorsGary L. Doll, Joseph P. Heremans
Life of this patent
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Abstract
Films of hexagonal boron nitride are converted to a highly desirable cubic-like phase of boron nitride. The transformation is achieved by annealing the hBN material at temperatures below 1000.degree. C. The conversion may be conducted in a hydrogen, nitrogen, ammonia, vacuum, or inert gas containing atmosphere.
Claims15
A method of solid state conversion of hexagonal to cubic-like boron nitride comprising:
- providing a noncrystalline film comprising hexagonal boron nitride film on a substrate,
- annealing the hexagonal boron nitride film in a gaseous atmosphere at a temperature below 1000.degree. C., at a pressure less than 2 GPa and without a catalyst so that a portion of the hexagonal boron nitride in the film is converted to cubic-like boron nitride.
A method of solid state conversion of hexagonal to cubic-like boron nitride comprising:
- providing a film comprising hexagonal boron nitride having limited crystalline structure on a substrate,
- heating the hexagonal boron nitride film in a furnace to a temperature ranging from about 600.degree. C. to less than 1000.degree. C., at a pressure less than 2 GPa and without a catalyst,
- gradually cooling the film so that a portion of the hexagonal boron nitride film is converted to cubic-like boron nitride.
Dependencies are inferred from the claim text.