Method for producing large soft hexagonal boron nitride particles
AssigneeGeneral Electric Company
InventorFrancis R. Corrigan
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Abstract
Soft hexagonal boron nitride crystals of 200-600 microns platelet size are produced from crystals of less than fifty microns particle size by mixing the small crystals with Li.sub.3 N, simultaneously heating and pressurizing said mixture to a temperature and pressure in a restricted region of the graphitic (hexagonal) boron nitride (GBN) stable region of the pressure-temperature (P-T) phase diagram of boron nitride, cooling and depressurizing said mixture, and separating off the water soluble material present in the mixture to leave a residue of large crystals of boron nitride.
Claims7
The method of producing soft hexagonal boron nitride crystals of larger than 50 microns average particle size which comprise the steps of:
- a. mixing graphitic boron nitride particles (GBN) of less than 50 microns average particle size and lithium nitride, the boron nitride comprising 50 to 85 mole percent of the boron nitride-lithium nitride mixture,
- b. simultaneously subjecting said mixture, and (d) separating the GBN crystals from the mixture to values of pressure and temperature within Region FBCE of the Figure;
- c. cooling and depressurizing said mixture.
The method of claim 6 wherein said GBN comprises about 43 weight percent of said mixture and the lithium nitride about 57 weight percent of said mixture.
Dependencies are inferred from the claim text.