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US4784978A
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Hexagonal boron nitride powder having excellent sinterability and a method for the preparation thereof
Assignee: JFE Steel Corp
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Filing: 1986-06-30
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Granted: 1988-11-15
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Expires: 2006-06-30
Abstract
Abstract The powder of hexagonal boron nitride is prepared by heat-treating a powdery mixture composed of an oxygen-containing boron compound, e.g. boric acid, and a nitrogen compound, e.g. dicyandiamide and melamine, with admixture of minor amounts of a carbonaceous powder, e.g. carbon black, and/or borax. Further, an alkaline earth metal compound such as calcium carbonate is added either to the powdery mixture of the starting materials before the heat treatment or to the powder after the heat treatment. The h-BN powder has excellent sinterability so that sintered bodies of boron nitride having a high density and high bending strength can readily be prepared by use of a hot press.
Inventors
- 👤 Takeshi Ogasawara
- 👤 Takahisa Koshida
- 👤 Toshimitsu Koitabashi
- 👤 Kimiaki Sasaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 14:22
CPC Classifications
C; C01; C01B; C01B21/00; C01B21/06; C01B21/064; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/583; C01B21/0648; C01P; C01P2002/00; C01P2002/60; C01P2006/00; C01P2006/10; C01P2006/80
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
61 words
A powder of hexagonal boron nitride with excellent sinterability having a purity of at least 95% by weight as boron nitride and containing an alkaline earth metal compound in an amount from 0.0001 to 0.1 mole calculated as alkaline earth metal per mole of boron, of which the crystallites (Lc) have a size in the range from 8 to 50 nm.
Claim 2
Dependent Claim
61 words
A powder of hexagonal boron nitride with excellent sinterability having a purity of at least 95% by weight as boron nitride and containing an alkaline earth metal compound in an amount from 0.0001 to 0.1 mole calculated as alkaline earth metal per mole of boron, of which the crystallites (Lc) have a size in the range from 8 to 50 nm.
Claim 3
Dependent Claim
65 words
A powder of hexagonal boron nitride with excellent sinterability having a purity of at least 95% by weight as boron nitride and containing a calcium oxide or a barium oxide in an amount from 0.0001 to 0.1 mole calculated as calcium or barium per mole of boron, of which the crystallites (L c ) have a size in the range from 8 to 50 nm.
Claim 4
Dependent Claim
65 words
A powder of hexagonal boron nitride with excellent sinterability having a purity of at least 95% by weight as boron nitride and containing a calcium oxide or a barium oxide in an amount from 0.0001 to 0.1 mole calculated as calcium or barium per mole of boron, of which the crystallites (L c ) have a size in the range from 8 to 50 nm.
Claim 5
Independent Claim
121 words
A method for the preparation of a powder of hexagonal boron nitride having excellent sinterability which comprises the steps of: (a) mixing boric acid, dehydrated boric acid, ammonium borate and a nitrogen compound selected from the group consisting of urea, melamine, dicyandiamide, cyanuric acid and ammonium chloride to produce a powdery mixture; (b) admixing the powdery mixture with 0.005 to 0.1 moles of a carbonaceous powder calculated as carbon per mole of boron in the powdery mixture and 2.5 to 30% by weight of borax or anhydrous borax calculated as anhydrous borax based on the boric acid, dehydrated boric acid and ammonium borate in the powdery mixture; and (c) subjecting the powdery mixture to a heat treatment in a non-oxidizing atmosphere.
Claim 6
Independent Claim
121 words
A method for the preparation of a powder of hexagonal boron nitride having excellent sinterability which comprises the steps of: (a) mixing boric acid, dehydrated boric acid, ammonium borate and a nitrogen compound selected from the group consisting of urea, melamine, dicyandiamide, cyanuric acid and ammonium chloride to produce a powdery mixture; (b) admixing the powdery mixture with 0.005 to 0.1 moles of a carbonaceous powder calculated as carbon per mole of boron in the powdery mixture and 2.5 to 30% by weight of borax or anhydrous borax calculated as anhydrous borax based on the boric acid, dehydrated boric acid and ammonium borate in the powdery mixture; and (c) subjecting the powdery mixture to a heat treatment in a non-oxidizing atmosphere.
Claim 7
Independent Claim
183 words
A method for the preparation of a powder of hexagonal boron nitride having excellent sinterability which comprises the steps of: (a) mixing boric acid, dehydrated boric acid, ammonium borate and a nitrogen compound selected from the group consisting of urea, melamine, dicyandiamide, cyanuric acid and ammonium chloride to produce a powdery mixture; (b) admixing the powdery mixture with 0.0001 to 0.1 mole of a calcium oxide or a barium oxide calculated as calcium or barium per mole of boron in the powdery mixture; (c) admixing the powdery mixture with a carbonaceous powder and at least one member selected from the group consisting of borax and anhydrous borax, the amount of the carbonaceous powder being in the range from 0.005 to 0.1 mole calculated as carbon per mole of boron in the powdery mixture and the amount of borax or anhydrous borax being in the range from 2.5 to 30% by weight calculated as anhydrous borax based on boric acid, dehydrated boric acid and ammonium borate in the powdery mixture; and (d) subjecting the powdery mixture to a heat treatment in a non-oxidizing atmosphere.
Claim 8
Independent Claim
183 words
A method for the preparation of a powder of hexagonal boron nitride having excellent sinterability which comprises the steps of: (a) mixing boric acid, dehydrated boric acid, ammonium borate and a nitrogen compound selected from the group consisting of urea, melamine, dicyandiamide, cyanuric acid and ammonium chloride to produce a powdery mixture; (b) admixing the powdery mixture with 0.0001 to 0.1 mole of a calcium oxide or a barium oxide calculated as calcium or barium per mole of boron in the powdery mixture; (c) admixing the powdery mixture with a carbonaceous powder and at least one member selected from the group consisting of borax and anhydrous borax, the amount of the carbonaceous powder being in the range from 0.005 to 0.1 mole calculated as carbon per mole of boron in the powdery mixture and the amount of borax or anhydrous borax being in the range from 2.5 to 30% by weight calculated as anhydrous borax based on boric acid, dehydrated boric acid and ammonium borate in the powdery mixture; and (d) subjecting the powdery mixture to a heat treatment in a non-oxidizing atmosphere.
Claim 9
Independent Claim
137 words
A method for the preparation of a powdery composition of hexagonal boron nitride having excellent sinterability which comprises the steps of: (a) mixing boric acid, dehydrated boric acid, ammonium borate and a nitrogen compound selected from the group consisting of urea, melamine, dicyandiamide, cyanuric acid and ammonium chloride to produce a powdery mixture; (b) admixing the powdery mixture with 0.005 to 0.1 mole of a carbonaceous powder calculated as carbon per mole of boron in the powdery mixture; (c) subjecting the powdery mixture to a heat treatment in a non-oxidizing atmosphere to obtain a powder of hexagonal boron nitride; and (d) admixing the powder of hexagonal boron nitride with 0.0001 to 0.1 mole of a calcium oxide or a barium oxide calculated as calcium or barium per mole of boron in the powder of hexagonal boron nitride.
Claim 10
Independent Claim
137 words
A method for the preparation of a powdery composition of hexagonal boron nitride having excellent sinterability which comprises the steps of: (a) mixing boric acid, dehydrated boric acid, ammonium borate and a nitrogen compound selected from the group consisting of urea, melamine, dicyandiamide, cyanuric acid and ammonium chloride to produce a powdery mixture; (b) admixing the powdery mixture with 0.005 to 0.1 mole of a carbonaceous powder calculated as carbon per mole of boron in the powdery mixture; (c) subjecting the powdery mixture to a heat treatment in a non-oxidizing atmosphere to obtain a powder of hexagonal boron nitride; and (d) admixing the powder of hexagonal boron nitride with 0.0001 to 0.1 mole of a calcium oxide or a barium oxide calculated as calcium or barium per mole of boron in the powder of hexagonal boron nitride.
Claim 11
Independent Claim
166 words
A method for the preparation of a powdery composition of hexagonal boron nitride having excellent sinterability which comprises the steps of: (a) mixing boric acid, dehydrated boric acid, ammonium borate and a nitrogen compound selected from the group consisting of urea, melamine, dicyandiamide, cyanuric acid and ammonium chloride to produce a powdery mixture; (b) admixing the powdery mixture with 0.005 to 0.1 mole of a carbonaceous powder calculated as carbon per mole of boron in the powdery mixture and 2.5 to 30% by weight of borax or anhydrous borax calculated as anhydrous borax based on boric acid, dehydrated boric acid and ammonium borate in the powdery mixture; (c) subjecting the powdery mixture to a heat treatment in a non-oxidizing atmosphere to obtain a powder of hexagonal boron nitride; and (d) admixing the powder of hexagonal boron nitride with 0.0001 to 0.1 mole of a calcium oxide or a barium oxide calculated as calcium or barium per mole of boron in the powder of hexagonal boron nitride.
Claim 12
Independent Claim
166 words
A method for the preparation of a powdery composition of hexagonal boron nitride having excellent sinterability which comprises the steps of: (a) mixing boric acid, dehydrated boric acid, ammonium borate and a nitrogen compound selected from the group consisting of urea, melamine, dicyandiamide, cyanuric acid and ammonium chloride to produce a powdery mixture; (b) admixing the powdery mixture with 0.005 to 0.1 mole of a carbonaceous powder calculated as carbon per mole of boron in the powdery mixture and 2.5 to 30% by weight of borax or anhydrous borax calculated as anhydrous borax based on boric acid, dehydrated boric acid and ammonium borate in the powdery mixture; (c) subjecting the powdery mixture to a heat treatment in a non-oxidizing atmosphere to obtain a powder of hexagonal boron nitride; and (d) admixing the powder of hexagonal boron nitride with 0.0001 to 0.1 mole of a calcium oxide or a barium oxide calculated as calcium or barium per mole of boron in the powder of hexagonal boron nitride.
Claim 13
Independent Claim
175 words
A method for the preparation of a powder of hexagonal boron nitride having excellent sinterability which comprises the steps of: (a) mixing boric acid, dehydrated boric acid, ammonium borate and a nitrogen compound selected from the group consisting of urea, melamine, dicyandiamide, cyanuric acid and ammonium chloride to produce a powdery mixture; (b) admixing the powdery mixture with 0.005 to 0.1 mole of a carbonaceous powder calculated as carbon per mole of boron in the powdery mixture; (c) admixing the powdery mixture with 0.0001 to 0.1 mole of a calcium oxide or barium oxide calculated as calcium or barium per mole of boron in the powdery mixture and 2.5 to 30% by weight of borax or anhydrous borax calculated as anhydrous borax based on boric acid, dehydrated boric acid and ammonium borate; (d) subjecting the powdery mixture to a heat treatment in a non-oxidizing atmosphere at a temperature of 900° to 1300° C. to obtain a crude powder of hexagonal boron nitride; and (e) washing the crude powder of hexagonal boron nitride followed by drying.
Claim 14
Independent Claim
175 words
A method for the preparation of a powder of hexagonal boron nitride having excellent sinterability which comprises the steps of: (a) mixing boric acid, dehydrated boric acid, ammonium borate and a nitrogen compound selected from the group consisting of urea, melamine, dicyandiamide, cyanuric acid and ammonium chloride to produce a powdery mixture; (b) admixing the powdery mixture with 0.005 to 0.1 mole of a carbonaceous powder calculated as carbon per mole of boron in the powdery mixture; (c) admixing the powdery mixture with 0.0001 to 0.1 mole of a calcium oxide or barium oxide calculated as calcium or barium per mole of boron in the powdery mixture and 2.5 to 30% by weight of borax or anhydrous borax calculated as anhydrous borax based on boric acid, dehydrated boric acid and ammonium borate; (d) subjecting the powdery mixture to a heat treatment in a non-oxidizing atmosphere at a temperature of 900° to 1300° C. to obtain a crude powder of hexagonal boron nitride; and (e) washing the crude powder of hexagonal boron nitride followed by drying.
Claim 15
Independent Claim
191 words
A method for the preparation of a powdery composition of hexagonal boron nitride having excellent sinterability which comprises the steps of: (a) mixing boric acid, dehydrated boric acid, ammonium borate and a nitrogen compound selected from the group consisting of urea, melamine, dicyandiamide, cyanuric acid and ammonium chloride to produce a powdery mixture; (b) admixing the powdery mixture with 0.005 to 0.1 mole of a carbonaceous powder calculated as carbon per mole of boron in the powdery mixture; (c) admixing the powdery mixture with 2.5 to 30% by weight of borax or anhydrous borax calculated as anhydrous borax based on the boric acid, dehydrated boric acid and ammonium borate in the powdery mixture; (d) subjecting the powdery mixture to a heat treatment in a non-oxidizing atmosphere at a temperature of 900° C. to 1300° C. to obtain a crude powder of hexagonal boron nitride; (e) washing the crude powder of hexagonal boron nitride followed by drying; and (f) admixing the dried powder of hexagonal boron nitride with 0.0001 to 0.1 mole of a calcium oxide or barium oxide calculated as calcium or barium per mole of boron in the dried powder.
Claim 16
Independent Claim
191 words
A method for the preparation of a powdery composition of hexagonal boron nitride having excellent sinterability which comprises the steps of: (a) mixing boric acid, dehydrated boric acid, ammonium borate and a nitrogen compound selected from the group consisting of urea, melamine, dicyandiamide, cyanuric acid and ammonium chloride to produce a powdery mixture; (b) admixing the powdery mixture with 0.005 to 0.1 mole of a carbonaceous powder calculated as carbon per mole of boron in the powdery mixture; (c) admixing the powdery mixture with 2.5 to 30% by weight of borax or anhydrous borax calculated as anhydrous borax based on the boric acid, dehydrated boric acid and ammonium borate in the powdery mixture; (d) subjecting the powdery mixture to a heat treatment in a non-oxidizing atmosphere at a temperature of 900° C. to 1300° C. to obtain a crude powder of hexagonal boron nitride; (e) washing the crude powder of hexagonal boron nitride followed by drying; and (f) admixing the dried powder of hexagonal boron nitride with 0.0001 to 0.1 mole of a calcium oxide or barium oxide calculated as calcium or barium per mole of boron in the dried powder.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-11-15 | 1992-05-16 | 1992-11-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-11-15 | 1996-05-16 | 1996-11-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-11-15 | 2000-05-16 | 2000-11-15 | $7700.00 | Window Closed / Lapsed |