EP0076731A2
Expired / Lapsed
EP
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Porous free standing pyrolytic boron nitride articles and method for preparing the same
Assignee: Union Carbide Corp
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Filing: 1982-09-27
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Granted: —
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Expires: 2002-09-27
Abstract
Abstract The invention deals with porous free standing pyrolytic boron nitride articles and a method for preparing the same. <??>A sponge-like free-standing pyrolytic boron article is made by reacting ammonia and gaseous boron halide diluted with an inert gas to deposit pyrolytic boron nitride on a porous substrate such as open-pored vitreous carbon under a vacuum and then removing the substrate as by oxidation.
Inventors
- 👤 Julius Steven Shinko
- 👤 Thomas Clyde Keyes
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-27 22:35
CPC Classifications
C; C23; C23C; C23C16/00; C23C16/01; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/583; C04B38/00; C04B38/0022; C04B38/0025; C04B38/0029
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
205 words
Method of making an open-pored article of pyrolytic boron nitride (PBN) article which comprises : (a) forming an open-pored porous substrate in the shape desired for the PBN article, (b) placing said substrate in a reaction chamber and maintaining said reaction chamber at a reaction temperature of from 1100 to 2000°C preferably from 1700 to 2000°C and at a reduced reaction pressure below 67 x 10 2 Pa while introducing into said reaction chamber ammonia vapor diluted with a non-oxidizing gas and a gaseous boron halide diluted such as for instance boron trichloride with a non-oxidizing gas, said non-oxidizing gas being preferably nitrogen or argon, (c) maintaining said reaction chamber at said reaction temperature and reaction pressure while continuing to admit said diluted ammonia vapor and diluted gaseous boron halide and while venting spent diluent gas to maintain said reaction pressure until the desired amount of PBN has been deposited on and in said substrate, (d) allowing said reaction chamber to cool to ambient temperature while maintaining a non-oxidizing atmosphere in said chamber, and (e) removing the PBN coating from a portion of the surface of said substrate to expose said substrate and then removing said substrate to leave the desired porous article of PBN.
Claim 2
Dependent Claim
205 words
Method of making an open-pored article of pyrolytic boron nitride (PBN) article which comprises : (a) forming an open-pored porous substrate in the shape desired for the PBN article, (b) placing said substrate in a reaction chamber and maintaining said reaction chamber at a reaction temperature of from 1100 to 2000°C preferably from 1700 to 2000°C and at a reduced reaction pressure below 67 x 10 2 Pa while introducing into said reaction chamber ammonia vapor diluted with a non-oxidizing gas and a gaseous boron halide diluted such as for instance boron trichloride with a non-oxidizing gas, said non-oxidizing gas being preferably nitrogen or argon, (c) maintaining said reaction chamber at said reaction temperature and reaction pressure while continuing to admit said diluted ammonia vapor and diluted gaseous boron halide and while venting spent diluent gas to maintain said reaction pressure until the desired amount of PBN has been deposited on and in said substrate, (d) allowing said reaction chamber to cool to ambient temperature while maintaining a non-oxidizing atmosphere in said chamber, and (e) removing the PBN coating from a portion of the surface of said substrate to expose said substrate and then removing said substrate to leave the desired porous article of PBN.
Claim 3
Dependent Claim
24 words
Method according to claim 1 wherein said substrate is an open-pored carbon foam such as for instance carbonized plastic foam or reticulated vitreous carbon.
Claim 4
Dependent Claim
35 words
Method according to claim 1 wherein in step d. the pressure in said reaction chamber is reduced to a cooling pressure of 1.3 Pa to 13 Pa and said pressure is maintained during said cooling.
Claim 5
Dependent Claim
61 words
Method according to claim 1 wherein said substrate is removed in step (e) by oxidizing away said substrate, more particularly wherein said substrate is an open-pored carbon foam and said substrate is removed in step (e) by oxidizing away said substrate in an oxidation chamber in an oxidizing atmosphere at an oxidation temperature of from 500 to 700°C, preferably about 700°C.
Claim 6
Dependent Claim
34 words
Method according to claim 1 wherein said inert gas is nitrogen, said reaction temperature in step (b) is about 1875°C and said reaction pressure in step (b) is about 0.5 x 10 2 Pa.
Claim 7
Dependent Claim
33 words
Method according to claim 1 or 2 wherein said ammonia vapor in step (b) is diluted with from 1.0 to 3.0 preferably 1.85 parts by volume of non-oxidizing gas per part of ammonia.
Claim 8
Dependent Claim
35 words
Method according to claim 1 or 2 wherein said gaseous boron halide in step (b) is diluted with from 10 to 15 preferably 13 parts by volume of non-oxidizing gas per part of boron halide.
Claim 9
Dependent Claim
42 words
Method according to claim 1 or 2 wherein the ratio of ammonia vapors to gaseous boron halide introduced into said reaction chamber in step (b) is from 2.0 to 3.0 preferably 2.7 parts by volume of ammonia per part of boron halide.
Claim 10
Dependent Claim
203 words
A freestanding open-pored porous article made of pyrolytic boron nitride (PBN) made by : (a) forming an open-pored substrate in the shape desired for the PBN article, (b) placing said substrate in a reaction chamber and maintaining said reaction chamber at a reaction temperature of from 1100 to 2000°C preferably from 1700 to 2000°C and at a reduced reaction pressure below 67 x 10 2 Pa while introducing into said reaction chamber ammonia vapor diluted with a non-oxidizing gas and a gaseous boron halide such as for instance boron trichloride diluted with a non-oxidizing gas, said non-oxidizing gas being preferably nitrogen or argon, (c) maintaining said reaction chamber at said reaction temperature and reaction pressure while continuing to admit said diluted ammonia vapor and diluted gaseous boron halide and while removing spent diluent gas to maintain said reaction pressure until the desired amount of PBN has been deposited on and in said substrate, (d) allowing said reaction chamber to cool to ambient temperature while maintaining a non-oxidizing atmosphere in said chamber, and (e) removing the PBN coating from a portion of the surface of said substrate to expose said substrate and then removing said substrate to leave the desired porous article of PBN.
Claim 11
Dependent Claim
203 words
A freestanding open-pored porous article made of pyrolytic boron nitride (PBN) made by : (a) forming an open-pored substrate in the shape desired for the PBN article, (b) placing said substrate in a reaction chamber and maintaining said reaction chamber at a reaction temperature of from 1100 to 2000°C preferably from 1700 to 2000°C and at a reduced reaction pressure below 67 x 10 2 Pa while introducing into said reaction chamber ammonia vapor diluted with a non-oxidizing gas and a gaseous boron halide such as for instance boron trichloride diluted with a non-oxidizing gas, said non-oxidizing gas being preferably nitrogen or argon, (c) maintaining said reaction chamber at said reaction temperature and reaction pressure while continuing to admit said diluted ammonia vapor and diluted gaseous boron halide and while removing spent diluent gas to maintain said reaction pressure until the desired amount of PBN has been deposited on and in said substrate, (d) allowing said reaction chamber to cool to ambient temperature while maintaining a non-oxidizing atmosphere in said chamber, and (e) removing the PBN coating from a portion of the surface of said substrate to expose said substrate and then removing said substrate to leave the desired porous article of PBN.
Claim 12
Dependent Claim
24 words
A free standing porous article of PBN according to claim 9 wherein said substrate is an open-pored carbon foam, such as carbonized plastic foam.
Claim 13
Dependent Claim
41 words
A free standing porous article of PBN according to claim 9 wherein in step (d) the pressure in said reactor chamber is reduced to a cooling pressure of 1.3 Pa to 13 Pa and said pressure is maintained during said cooling.
Claim 14
Dependent Claim
48 words
A free-standing porous article of PBN according to claim 9 wherein said substrate is an open-pored carbon foam and said substrate is removed in step (e) by oxidizing away said substrate in an oxidation chamber in an oxidizing atmosphere at an oxidation temperature of from 500 to 700°C.
Claim 15
Dependent Claim
51 words
A free standing porous article of PBN according to claims 9, 10, 11 or 12 wherein the ratio of ammonia vapors to gaseous boron halide introduced into said reaction chamber in step (b) is from about 2.0 to 3.0 preferably 2.7 parts by volume of ammonia per part of boron halide.
References Cited (Backward Citations)
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