GB1574077A - Bn bonded bn fibre article from bn fibre or partially nitrided boron oxide fibre - Google Patents
Bn bonded bn fibre article from bn fibre or partially nitrided boron oxide fibre Download PDFInfo
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- GB1574077A GB1574077A GB4134277A GB4134277A GB1574077A GB 1574077 A GB1574077 A GB 1574077A GB 4134277 A GB4134277 A GB 4134277A GB 4134277 A GB4134277 A GB 4134277A GB 1574077 A GB1574077 A GB 1574077A
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- United Kingdom
- Prior art keywords
- boron oxide
- fibers
- fiber
- article
- boron
- Prior art date
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- 239000000835 fiber Substances 0.000 title claims description 116
- 229910052810 boron oxide Inorganic materials 0.000 title claims description 83
- JKWMSGQKBLHBQQ-UHFFFAOYSA-N diboron trioxide Chemical compound O=BOB=O JKWMSGQKBLHBQQ-UHFFFAOYSA-N 0.000 title claims description 83
- PZNSFCLAULLKQX-UHFFFAOYSA-N Boron nitride Chemical compound N#B PZNSFCLAULLKQX-UHFFFAOYSA-N 0.000 claims description 66
- 229910052582 BN Inorganic materials 0.000 claims description 65
- 238000000034 method Methods 0.000 claims description 58
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 48
- 238000010438 heat treatment Methods 0.000 claims description 28
- 229910021529 ammonia Inorganic materials 0.000 claims description 21
- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Chemical compound [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 claims description 20
- 239000000203 mixture Substances 0.000 claims description 15
- 239000007788 liquid Substances 0.000 claims description 14
- 238000002844 melting Methods 0.000 claims description 14
- 230000008018 melting Effects 0.000 claims description 14
- 239000007787 solid Substances 0.000 claims description 12
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 10
- 238000002156 mixing Methods 0.000 claims description 9
- 239000007789 gas Substances 0.000 claims description 8
- 238000006243 chemical reaction Methods 0.000 claims description 6
- 230000000694 effects Effects 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 230000008020 evaporation Effects 0.000 claims description 5
- 238000001704 evaporation Methods 0.000 claims description 5
- 229910052757 nitrogen Inorganic materials 0.000 claims description 5
- 229960005419 nitrogen Drugs 0.000 claims description 5
- 238000000354 decomposition reaction Methods 0.000 claims description 4
- 239000003350 kerosene Substances 0.000 claims description 4
- 238000007664 blowing Methods 0.000 claims description 3
- 239000011261 inert gas Substances 0.000 claims description 3
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims 1
- 229910052796 boron Inorganic materials 0.000 claims 1
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 230000004927 fusion Effects 0.000 description 3
- 238000005121 nitriding Methods 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 238000003825 pressing Methods 0.000 description 3
- 230000001419 dependent effect Effects 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 235000011164 potassium chloride Nutrition 0.000 description 2
- 239000001103 potassium chloride Substances 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 description 1
- 239000004327 boric acid Substances 0.000 description 1
- 150000001639 boron compounds Chemical class 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000011094 fiberboard Substances 0.000 description 1
- GLNWILHOFOBOFD-UHFFFAOYSA-N lithium sulfide Chemical compound [Li+].[Li+].[S-2] GLNWILHOFOBOFD-UHFFFAOYSA-N 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- SNICXCGAKADSCV-UHFFFAOYSA-N nicotine Chemical compound CN1CCCC1C1=CC=CN=C1 SNICXCGAKADSCV-UHFFFAOYSA-N 0.000 description 1
- 239000000615 nonconductor Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- MOWNZPNSYMGTMD-UHFFFAOYSA-N oxidoboron Chemical compound O=[B] MOWNZPNSYMGTMD-UHFFFAOYSA-N 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000000123 paper Substances 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 238000009987 spinning Methods 0.000 description 1
- 239000002470 thermal conductor Substances 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
- H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
- H01B3/48—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances fibrous materials
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
- C04B35/58—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides
- C04B35/583—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides based on boron nitride
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/62227—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products obtaining fibres
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/42—Housings not intimately mechanically associated with radiating elements, e.g. radome
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Ceramic Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Structural Engineering (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Ceramic Products (AREA)
- Inorganic Fibers (AREA)
- Porous Artificial Stone Or Porous Ceramic Products (AREA)
- Cell Separators (AREA)
- Chemical Or Physical Treatment Of Fibers (AREA)
Description
(54) BN BONDED BN FIBRE ARTICLE FROM BN FIBRE OR PARTIALLY
NITRIDED BORON OXIDE FIBRE
(71) We, THE CARBORUNDUM COM- PANY, a corporation duly organised and existing under the laws of the State of Delaware, United States of America, of 1625
Buffalo Avenue, Niagara Falls, New York,
United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: - This invention relates to boron nitride fibers and more particularly relates to articles manufactured from integral three dimensional boron nitride fiber mats. The invention further relates to the method for the manufacture of such articles.
Boron nitride (BN) possesses a number of highly desirable properties which render it useful in a wide variety of applications. Its high electrical resistivity coupled with its high thermal conductivity make it especially useful in electrical and electronic applications requiring a material which simultaneously acts as an electrical insulator and a thermal conductor. Its excellent thermal shock resistance renders it effective as a refractory at temperatures up to 1,600 C.
or higher in a non-oxidizing atmosphere and at temperatures as high as 700 to 900"C. in air. It is highly corrosion resistant, being inert to most organic liquids and many corrosive chemicals and displaying excellent resistance to attack by various molten metals. Furthermore, because of its low dissipation factor over a wide temperature range, this material is well suited for use in microwave and radar dielectric components (radar windows). Various methods for the manufacture of boron nitride fibers are known in the prior art, for example, it is disclosed in U.S. Patent 3,429,722 issued to
James Economy et al. that boron nitride fibers can be manufactured by heating boron oxide fibers in an ammonia atmosphere.
U.S. Patent 3,668,059 issued to James
Economy et al. discloses a boron nitride fiber having a high Young's modulus of
elasticity which is prepared by heating a partially nitrided fiber in an inert atmosphere at a temperature of at least 1800 C.
under longitudinal tension.
While it is well known in the prior art that boron nitride fibers can be -manufactured having good characteristics, the use of such fibers -has been limited due to difficulties in forming three dimensional articles from the fibbers. Almost any substance which is used to bond the fibers to each other has properties which are inferior to the properties of the boron nitride fibers thus resulting in a bonded article which is unsuitable for use in many applications.
For example, when a boron nitride fiber article, which is bound by prior art ma trials, is used as a separator material in a
corrosive cell electrolyte such as molten lithium chloride and potassium chloride, the fibers separate from each other due to the inability of the binding material to withstand the high temperature corrosive environment.
An - attempt has been made prior to the present invention to form articles from boron nitride bonded boron nitride fibers by heating boron nitride fibers impregnated with boric acid solution to elevated temperatures in ammonia as disclosed in U.S.
Patent 3,837,997 to James Economy et al.
In addition to the above-noted references relating to boron nitride fibers, shaped boron nitride usually non-porous bodies have also been prepared in the past. Such articles are disclosed, for example, by
Taylor, U.S. Patent 2,888,325, which teaches the use of a multiple stage nitriding process comprising intermittent addition of oxygen-containing boron compound at intrmediate stages of nitriding, followed by further nitriding.
Furthermore, such articles have been prepared by sintering boron nitride fibers in the presence of boron oxide.
None of these methods resulted in a nonwoven porous boron nitride fiber-article having sufficient strength for use as an
electric cell separator in molten lithium chloride environments. These bonding processes sometimes resulted in a boron nitride fiber of reduced strength or the bond was of insufficient strength or durability to secure the fibers to each other in molten lithium chloride environments.
According to the present invention there is provided a method for manufacturing a boron nitride article comprising:
(a) blending under anhydrous conditions from 2 to 40 weight percent. of total solids of boron oxide with from 60 to 98 weight percent. of total solids of boron nitride fiber or partially nitrided boron oxide fiber;
(b) forming a shaped article with the resulting blend;
(c) heating the article in an anhydrous gas selected from inert gasses, nitrogen, ammonia and mixtures thereof to a temperature above the melting temperature of the boron oxide and below the melting or decomposition temperature of said fiber for a time sufficient to melt at least some of the boron oxide to the fibers; and
(d) heating the article in an ammonia atmosphere to a sufficient temperature and for a sufficient time to convert essentially all of the boron oxide to boron nitride.
The resulting article comprises boron nitride fibers fused to each other with boron nitride which article has good strength, good dimensional stability, good chemical resistance, good heat resistance, is relatively non-brittle compared with prior art boron nitride fiber articles and retains the desirable characteristics, i.e., porosity of a fiber article.
The article manufactured in accordance with the method of the invention can be of any desirable shape. For example, the article may be spherical, cubic, cylindrical, oval, a bar or in the form of a plate or mat.
The article may be provided with holes or contours if desired for a particular application. The article comprises a body of boron nitride fibers which are secured to each other at fiber intersections by partially or completely nitrided boron oxide. Desirably, the boron oxide is completely nitrided to form boron nitride.
One example of a desirable article manufactured in accordance with the process of the invention, is a fiber mat which has sufficient porosity, strength and chemical resistance to be used as a separator in lithium-sulfide batteries utilizing molten lithium chloride and molten potassium chloride as the electrolyte.
In accordance with the method of the invention from 2 to 40 weight percent. and preferably from 5 to 20 weight percent. of boron oxide is blended with from 60 to 98 weight percent. and preferably from 80 to 95 weight percent. of boron nitride or partially nitrided boron oxide fibers. The most desirable concentration of boron oxide is from 10 to 20 weight percent. and the most desirable concentration of boron nitride or partially nitrided boron oxide is from 80 to 90 weight percent.
The boron oxide may be particulate or fibrous in form. When the boron oxide is fibrous, the boron oxide (B2Oa) fibers desirably have a maximum diameter of 20 microns and most desirably, a maximum diameter of 20 microns and most desirably, a maximum diameter of about 10 microns.
When the B203 is particulate, the average particle size may vary from sub-micron to about 100 microns in diameter and the particles may be of any shape. The boron nitride or partially nitrided boron oxide fibers similarly have a maximum diameter of 30 microns, more desirably a maximum diameter of 20 microns and most desirably, a maximum diameter of about 10 microns.
The boron nitride or partially nitrided boron oxide is desirably made by heating boron oxide fibers in an ammonia atmosphere in accordance with known procedures as for example are disclosed in U.S. Patents 3,429,722 and 3,668,059 both issued to
James Economy. Boron oxide fibers when used may be made by any known method including spinning the boron oxide (B203) fibers from a B2O3- melt and winding the resulting fibers upon a reel in an atmosphere protected from moisture. Alternatively the B203 precursor fibers may be blown in staple form from a B203 melt.
The boron nitride or partially nitrided boron oxide fibers may be blended with boron oxide under anhydrous conditions by any suitable means such as by slurrying the fibers in an anhydrous liquid and subsequently removing the liquid from the fibers. The liquid should not dissolve the boron oxide or the fibre, and is preferably kerosene which may be removed by evaporation. Other methods for blending include blowing the fibers and boron oxide, whether in fiber or particle form, into a container or mixing in a fluidized bed.
After the fibers are blended with boron oxide, the resulting composition is formed into a shaped article by any suitable means.
For example, the shaped article may be formed by pressing the composition into the appropriate shape. Molds may be used if desired during the pressing procedure.
Fiber mats and fiber boards can be manufactured by pressing the blend between flat plates. Pressures which can be used during the forming procedure preferably range between about 05 and about 25 kilograms per square centimetre absolute. The pressure can be maintained during the heating.
Shaped articles can also be formed from the blend by casting a slurry of the blend in an anhydrous liquid followed by subsequent evaporation of the liquid. The slurry may be cast into a mold or on to a flat surface.
After the article is formed, it is heated in an anhydrous gas selected from inert gases, nitrogen, ammonia and mixtures thereof to a temperature above the melting temperature of the boron oxide for a time sufficient to fuse at least some of the boron oxide to the boron nitride fibers and for a time insufficient to destroy the boron nitride or partially nitrided boron oxide fibers by melting. In general, the heating temperature is from 460 to 14000 C. Desirably the heating temperature is below about 750"C. since higher temperatures tend to result in localized rather than uniform fusion of the fibers to each other by boron oxide throughout the article, particularly when heat transfer is not substantially enhanced by flow of heated gas through the article.
The time required to fuse the fibers together, without destroying the fibers by melting or decomposition is dependent upon the fusion temperature used and heat transfer methods employed. At higher temperatures, short heating times are required and rapid heat transfer throughout the article is needed to prevent localized evaporation of the B203 before the fibers throughout the article are fused to each other. Such heat transfer is generally accomplished by rapidly circulating heated gas through the fibers.
At higher temperatures, i.e., from 750"C. to 1400"C., the time sufficient to fuse at least some of the boron oxide to the boron nitride fibers is generally between 3 and 60 minutes.
In general, it has been found that a slow temperature rise to the desired peak temperature over the heating time results in a more uniform article.
At lower temperatures, i.e., from 450"C.
to 750 C., longer heating times are required for sufficient fusion of the boron oxide to the boron nitride or partially nitrided boron oxide fibers. However, even at the lower temperatures, good heat transfer between the fibers is desirable to obtain a uniform article. At lower temperatures, the sufficient time to fuse the fibers is generally between 1 and 6 hours. Again, it has been found that a more uniform article is obtained when the heating temperature is slowly elevated to the peak temperature over the heating time.
The heating of the article in an ammonia atmosphere to a sufficient temperature and for a sufficient time to convert the boron oxide to boron nitride may occur simultaneously with or subsequent to the heating of the article in an anhydrous gas to fuse the boron oxide to the boron nitride or partially nitrided boron oxide fibers.
In general, the sufficient temperature to convert the boron oxide to boron nitride in an ammonia atmosphere is any temperature above the reaction temperature of ammonia with boron oxide up to the melting temperature of boron nitride. In general, the sufficient temperature to convert the boron oxide to boron nitride is from 200"C. to 900"C. When partially nitrided boron oxide fibers are used, they are converted to boron nitride during this conversion step.
The time which is required to convert the boron oxide to boron nitride depends mainly upon the diffusion rate of ammonia into the fibers which in turn is dependent upon the concentration of ammonia gas and the flow or contact of the ammonia gas with the boron oxide and to some extent, the gas temperature. In general, the sufficient time to convert the boron oxide at temperatures between 200"C. and 900"C. in ammonia gas at atmospheric pressure with sufficient flow of ammonia through the fibers to provide excess ammonia gas reactant, is from 2 to 18 hours. Longer times may be used without detriment to the article but have not been found to be necessary.
The following examples serve to illustrate the process and article of the invention without limiting the invention:
EXAMPLE I
7 grams of BN fibers having an average diameter of about 4sA and an average length of between about 05 to about 09 centimetre is blended with 3 grams of B203 fibers having an average diameter of about 4y and an average length of between about 1 and about 2 centimetres. The blending is accomplished by covering a mixture of the fibers with kerosene and blending the resulting composition in a food blender at about 3,200 rpm for about two minutes.
The composition is then cast into a sheet in a mold about 4 centimetres square and dried and heated up to 650"C. over a four hour period in an oven. The resulting sheet is then allowed to cool for eight hours in the oven which is nitrogen purged.
The sheet is then removed, cut in half and heated in an oven, at temperature rise of 100"C. per hour up to 900"C., in ammonia at atmospheric pressure. Ammonia flow through the oven is 15 litres per minute. The resulting sheet is flexible, porous, strong and is able to withstand a molten lithium chloride environment for an extended time period without deterioration.
EXAMPLE 2
Example 1 is repeated except 6 grams of
BN fiber and 4 grams of B203 fiber are used. The resulting sheet is flexible, porous, strong and is able to withstand a molten lithium chloride environment for an extended period without deterioration.
EXAMPLE 3
Example 2 is repeated except 5 grams of
BN fiber and 5 grams of B2O, fiber are
used. The results are the same as Example
2 except the sheet is not flexible and has
reduced porosity.
EXAMPLE 4
The procedure of Example 1 is followed
except 8 5 grams of BN fiber and 1.5 grams
of B203 fiber are used and after heating in
ammonia, the resulting sheet is heated in
air at 6000C. for 2 hours. The resulting
sheet has all of the desirable properties of
the sheet prepared in Example 1 and in
addition is more flexible and more uniform.
EXAMPLE 5
The procedure of Example 4 is followed
except partially nitrided B203 fibers are
substituted for the BN fibers. The partially
nitrided B203 fibers are prepared in ac
cordance with the teaching of Example 2
of U.S. Patent 3,668,059 wherein boron
oxide fibers are heated in flowing ammonia
gas at 210 C. for 0.5 hours, from 210"C. to 550 C. at a rate of 4"C. per hour, from 550"C. to 6400C. at a rate of 15"C. per
hour, and then at 640"C. for one hour.
The resulting product is a strong BN bonded
BN fiber paper which is resistant to molten
lithium chloride.
WHAT WE CLAIM IS:- 1. A method for manufacturing a boron
nitride article comprising:
(a) blending under anhydrous conditions
from 2 to 40 weight percent. of total
solids of boron oxide with from 60
to 98 weight percent. of total solids
of boron nitride fiber or partially
nitrided boron oxide fiber;
(b) forming a shaped article with the re
sulting blend;
(c) heating the article in an anhydrous
gas selected from inert gases, nitro
gen, ammonia and mixtures thereof
to a temperature above the melting
temperature of the boron oxide and
below the melting or decomposition
temperature of said fiber for a time
sufficient to melt at least some of the
boron oxide to the fibers; and
(d) heating the article in an ammonia at
mosphere to a sufficient temperature
and for a sufficient time to convert
essentially all of the boron oxide to
boron nitride.
2. A method as claimed in Claim 1
wherein from 5 to 20 weight percent. of
total solids of boron oxide is blended with ,from 80 to 95 weight percent. of total solids . f sabd dber.
O. A method as claimed in Claim 2 .wherein - from 80 to 90 weight percent. of
total sods of boron oxide is blended with
10 to 20 weight percent. of total solids of said fiber.
4. A method as claimed in any one of
Claims 1 to 3 wherein the boron oxide is in particulate form.
5. A method as claimed in any one of
Claims 1 to 3 wherein the boron oxide is in fiber form.
6. A method as claimed in any one of
Claims 1 to 5 wherein said fiber is boron nitride.
7. A method as claimed in any one of
Claims 1 to 6 wherein said article is heated to a temperature between 460"C. and 1400 C. to effect melting of the boron oxide.
8. A method as claimed in Claim 7 wherein said temperature between 460"C.
and 1400"C. is maintained for from three minutes to six hours.
9. A method as claimed in any one of
Claims 1 to 7 wherein the heating to effect said melting of the boron oxide and the -heating to effect said conversion of boron oxide to boron nitride are done simultaneously in an ammonia atmosphere.
10. A method as claimed in any one of
Claims 1 to 9 wherein the sufficient temperature to convert boron oxide is from 200 to 900 C. and the sufficient conversion time is from 2 to 18 hours.
11. A method as claimed in any one of
Claims 1 to 10 wherein the fibers are blended with boron oxide by slurrying the fibers and boron oxide in an anhydrous liquid in which the boron oxide and the fibers are insoluble, and the liquid is subsequently removed.
12. A method as claimed in Claim 11 wherein the liquid is kerosene and the liquid is removed by evaporation.
13. A method claimed in any one of
Claims 1 to 10 wherein the fibers and boron oxide are blended by blowing them randomly into a container.
14. A method asclaimed in any one of
Claims 1 to 10 wherein the fibers and boron oxide are blended by mixing them in a fluidized bed.
15. A method as claimed in any one of
Claims 1 to 14 wherein from 0.5 kilograms per square centimetre to 2 5 kilograms per square centimetre of absolute pressure is applied to said shaped article during said heating.
16. A method as claimed in any one of
Claims 1 to 15 wherein the shaped article is a fiber-mat.
17. A boron nitride article when produced bythe method of anyone of Claims
1 to 16.
18. A boron nitride fiber mat produced by the method of Claim 16.
19. An electric cell incorporating molten lithium chloride and a porous separator
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (1)
- **WARNING** start of CLMS field may overlap end of DESC **.EXAMPLE 3 Example 2 is repeated except 5 grams of BN fiber and 5 grams of B2O, fiber are used. The results are the same as Example2 except the sheet is not flexible and has reduced porosity.EXAMPLE 4 The procedure of Example 1 is followed except 8 5 grams of BN fiber and 1.5 grams of B203 fiber are used and after heating in ammonia, the resulting sheet is heated in air at 6000C. for 2 hours. The resulting sheet has all of the desirable properties of the sheet prepared in Example 1 and in addition is more flexible and more uniform.EXAMPLE 5 The procedure of Example 4 is followed except partially nitrided B203 fibers are substituted for the BN fibers. The partially nitrided B203 fibers are prepared in ac cordance with the teaching of Example 2 of U.S. Patent 3,668,059 wherein boron oxide fibers are heated in flowing ammonia gas at 210 C. for 0.5 hours, from 210"C. to 550 C. at a rate of 4"C. per hour, from 550"C. to 6400C. at a rate of 15"C. per hour, and then at 640"C. for one hour.The resulting product is a strong BN bonded BN fiber paper which is resistant to molten lithium chloride.WHAT WE CLAIM IS:- 1. A method for manufacturing a boron nitride article comprising: (a) blending under anhydrous conditions from 2 to 40 weight percent. of total solids of boron oxide with from 60 to 98 weight percent. of total solids of boron nitride fiber or partially nitrided boron oxide fiber; (b) forming a shaped article with the re sulting blend; (c) heating the article in an anhydrous gas selected from inert gases, nitro gen, ammonia and mixtures thereof to a temperature above the melting temperature of the boron oxide and below the melting or decomposition temperature of said fiber for a time sufficient to melt at least some of the boron oxide to the fibers; and (d) heating the article in an ammonia at mosphere to a sufficient temperature and for a sufficient time to convert essentially all of the boron oxide to boron nitride.2. A method as claimed in Claim 1 wherein from 5 to 20 weight percent. of total solids of boron oxide is blended with ,from 80 to 95 weight percent. of total solids . f sabd dber.O. A method as claimed in Claim 2 .wherein - from 80 to 90 weight percent. of total sods of boron oxide is blended with10 to 20 weight percent. of total solids of said fiber.4. A method as claimed in any one of Claims 1 to 3 wherein the boron oxide is in particulate form.5. A method as claimed in any one of Claims 1 to 3 wherein the boron oxide is in fiber form.6. A method as claimed in any one of Claims 1 to 5 wherein said fiber is boron nitride.7. A method as claimed in any one of Claims 1 to 6 wherein said article is heated to a temperature between 460"C. and 1400 C. to effect melting of the boron oxide.8. A method as claimed in Claim 7 wherein said temperature between 460"C.and 1400"C. is maintained for from three minutes to six hours.9. A method as claimed in any one of Claims 1 to 7 wherein the heating to effect said melting of the boron oxide and the -heating to effect said conversion of boron oxide to boron nitride are done simultaneously in an ammonia atmosphere.10. A method as claimed in any one of Claims 1 to 9 wherein the sufficient temperature to convert boron oxide is from 200 to 900 C. and the sufficient conversion time is from 2 to 18 hours.11. A method as claimed in any one of Claims 1 to 10 wherein the fibers are blended with boron oxide by slurrying the fibers and boron oxide in an anhydrous liquid in which the boron oxide and the fibers are insoluble, and the liquid is subsequently removed.12. A method as claimed in Claim 11 wherein the liquid is kerosene and the liquid is removed by evaporation.13. A method claimed in any one of Claims 1 to 10 wherein the fibers and boron oxide are blended by blowing them randomly into a container.14. A method asclaimed in any one of Claims 1 to 10 wherein the fibers and boron oxide are blended by mixing them in a fluidized bed.15. A method as claimed in any one of Claims 1 to 14 wherein from 0.5 kilograms per square centimetre to 2 5 kilograms per square centimetre of absolute pressure is applied to said shaped article during said heating.16. A method as claimed in any one of Claims 1 to 15 wherein the shaped article is a fiber-mat.17. A boron nitride article when produced bythe method of anyone of Claims1 to 16.18. A boron nitride fiber mat produced by the method of Claim 16.19. An electric cell incorporating molten lithium chloride and a porous separatorcomprising a boron fiber mat as claimed in Claim 18.20. A method for manufacturing a boron nitride article substantially as hereinbefore described in any one of the Examples.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US77358777A | 1977-03-02 | 1977-03-02 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1574077A true GB1574077A (en) | 1980-09-03 |
Family
ID=25098737
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB4134277A Expired GB1574077A (en) | 1977-03-02 | 1977-10-05 | Bn bonded bn fibre article from bn fibre or partially nitrided boron oxide fibre |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS53106714A (en) |
| BE (1) | BE860178A (en) |
| CA (1) | CA1085596A (en) |
| DE (1) | DE2748853C2 (en) |
| FR (1) | FR2382411A1 (en) |
| GB (1) | GB1574077A (en) |
| NL (1) | NL7712016A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0048278A1 (en) * | 1980-03-28 | 1982-03-31 | Kennecott Corp | Process for manufacturing boron nitride fiber felt using a fourdrinier machine. |
| EP0048276A1 (en) * | 1980-03-28 | 1982-03-31 | Kennecott Corp | Process for manufacturing boron nitride fiber mats using calender rolls. |
| EP0048275A1 (en) * | 1980-03-28 | 1982-03-31 | Kennecott Corp | Process for manufacturing boron nitride fiber mats. |
| WO2008108484A1 (en) * | 2007-03-05 | 2008-09-12 | Teijin Limited | Boron nitride fiber paper and method for producing the same |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0562227U (en) * | 1991-06-28 | 1993-08-20 | ユニ・チャーム株式会社 | Worn articles |
| US9845269B2 (en) * | 2012-03-30 | 2017-12-19 | National Institute Of Aerospace Associates | Multi-functional BN—BN composite |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1337264A (en) * | 1914-10-21 | 1920-04-20 | Chemical Foundation Inc | Process of making solid bodies from nitrids |
| GB483201A (en) * | 1936-07-31 | 1938-04-13 | British Thomson Houston Co Ltd | Improvements in and relating to boron nitride and methods of producing the same |
| US3399979A (en) * | 1963-11-01 | 1968-09-03 | Union Carbide Corp | Process for producing metal nitride fibers, textiles and shapes |
| US3429722A (en) * | 1965-07-12 | 1969-02-25 | Carborundum Co | Boron nitride fiber manufacture |
| US3573969A (en) * | 1968-08-19 | 1971-04-06 | Lockheed Aircraft Corp | Method for surface nitriding boron filaments |
| US3837997A (en) * | 1971-03-16 | 1974-09-24 | Carborundum Co | Boron nitride products |
| US3816242A (en) * | 1972-04-17 | 1974-06-11 | Standard Oil Co | Process for producing boron nitride felt |
| US3915742A (en) * | 1974-05-07 | 1975-10-28 | Us Energy | Interelectrode separator for electrochemical cell |
-
1977
- 1977-09-27 CA CA287,634A patent/CA1085596A/en not_active Expired
- 1977-10-05 GB GB4134277A patent/GB1574077A/en not_active Expired
- 1977-10-27 BE BE182117A patent/BE860178A/en not_active IP Right Cessation
- 1977-10-28 JP JP12880777A patent/JPS53106714A/en active Granted
- 1977-10-31 DE DE19772748853 patent/DE2748853C2/en not_active Expired
- 1977-11-01 NL NL7712016A patent/NL7712016A/en not_active Application Discontinuation
- 1977-11-02 FR FR7732903A patent/FR2382411A1/en active Granted
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0048278A1 (en) * | 1980-03-28 | 1982-03-31 | Kennecott Corp | Process for manufacturing boron nitride fiber felt using a fourdrinier machine. |
| EP0048276A1 (en) * | 1980-03-28 | 1982-03-31 | Kennecott Corp | Process for manufacturing boron nitride fiber mats using calender rolls. |
| EP0048275A1 (en) * | 1980-03-28 | 1982-03-31 | Kennecott Corp | Process for manufacturing boron nitride fiber mats. |
| EP0048275A4 (en) * | 1980-03-28 | 1982-07-13 | Kennecott Corp | Process for manufacturing boron nitride fiber mats. |
| EP0048278A4 (en) * | 1980-03-28 | 1982-07-13 | Kennecott Corp | Process for manufacturing boron nitride fiber felt using a fourdrinier machine. |
| EP0048276A4 (en) * | 1980-03-28 | 1982-07-13 | Kennecott Corp | Process for manufacturing boron nitride fiber mats using calender rolls. |
| WO2008108484A1 (en) * | 2007-03-05 | 2008-09-12 | Teijin Limited | Boron nitride fiber paper and method for producing the same |
| US8025766B2 (en) | 2007-03-05 | 2011-09-27 | Teijin Limited | Boron nitride-based fiber paper and manufacturing process thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| NL7712016A (en) | 1978-09-05 |
| DE2748853C2 (en) | 1986-04-10 |
| FR2382411B1 (en) | 1983-10-28 |
| JPS53106714A (en) | 1978-09-18 |
| DE2748853A1 (en) | 1978-08-31 |
| CA1085596A (en) | 1980-09-16 |
| FR2382411A1 (en) | 1978-09-29 |
| BE860178A (en) | 1978-04-27 |
| JPS6120508B2 (en) | 1986-05-22 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PS | Patent sealed | ||
| 732 | Registration of transactions, instruments or events in the register (sect. 32/1977) | ||
| PCNP | Patent ceased through non-payment of renewal fee | ||
| PCPE | Delete 'patent ceased' from journal |
Free format text: 4972 PAGE 1965 |
|
| PCNP | Patent ceased through non-payment of renewal fee |