Patent EP0061611A1 successfully refreshed from Google Patents.
EP0061611A1
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EP
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Method for producing pre-shaped alpha-silicon nitride whisker compacts and loose whiskers for composite material reinforcement
Assignee: Boeing Co
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Filing: 1982-03-08
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Granted: —
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Expires: 2002-03-08
Abstract
Abstract Method for producing pre-shaped a-silicon nitride whisker compacts and loose whiskers for composite material reinforcement, lies in the field of producing uncontaminated silicon nitride whiskers which previously could not be accomplished without high cost. The present invention provides for production of uncontaminated a-silicon nitride whiskers at a reasonable cost as either shaped preform or individual whiskers by blending silicon particles with composition particles, compacting the blend of silicon and composition particles to a shaped preform, subliming the composition particles to produce a shaped porous silicon precursor, and reacting the precursor with nitrogen. The shaped whisker compact can be impregnated with various materials to form composites, or can be broken down to individual whiskers to be used in molding powders.
Inventors
- 👤 Frederick H. Simpson
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 09:58
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/71; C04B35/78; C04B35/80; C04B35/01; C04B35/10; C04B35/111; C04B35/117; C04B35/14; C04B35/515; C04B35/52; C04B35/58; C04B35/581; C04B35/622; C04B35/62227; C04B35/62272; C04B35/62286; C04B35/62295; C04B35/626; C04B35/62605; C04B35/62645; C04B35/6268; C04B35/63; C04B35/6303; C04B35/6316; C04B35/64; C04B35/645; C30; C30B; C30B25/00; C30B25/005; C30B29/00; C30B29/10; C30B29/38; C04B2235/00; C04B2235/02; C04B2235/30; C04B2235/34; C04B2235/3409; C04B2235/42; C04B2235/428; C04B2235/46; C04B2235/465; C04B2235/50; C04B2235/52; C04B2235/5208; C04B2235/5216; C04B2235/524; C04B2235/5268; C04B2235/5276; C04B2235/54; C04B2235/5418; C04B2235/5436; C04B2235/60; C04B2235/604; C04B2235/616; C04B2235/70; C04B2235/96; C04B2235/9607; C04B2235/9623; C04B38/00; C04B38/0051; C04B38/0058
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
108 words
A method for producing a pre-shaped compact of omni-directional£-silicon nitride whiskers comprising the steps of: (a) blending silicon particles with fugitive composition particles able to sublime without leaving a residue; (b) compacting the blend to a desired shape; (c) subliming said fugitive composition particles from said compacted shape to form a porous silicon precursor compact having said desired shape; (d) reacting said shaped silicon compact with a substance that releases free nitrogen, said reaction occuring at a temperature sufficiently high to convert said shaped silicon compact to an identically shaped porous compact of α-silicon nitride whiskers but sufficiently low to avoid subliming substantially all of said formed whiskers.
Claim 2
Independent Claim
108 words
A method for producing a pre-shaped compact of omni-directional£-silicon nitride whiskers comprising the steps of: (a) blending silicon particles with fugitive composition particles able to sublime without leaving a residue; (b) compacting the blend to a desired shape; (c) subliming said fugitive composition particles from said compacted shape to form a porous silicon precursor compact having said desired shape; (d) reacting said shaped silicon compact with a substance that releases free nitrogen, said reaction occuring at a temperature sufficiently high to convert said shaped silicon compact to an identically shaped porous compact of α-silicon nitride whiskers but sufficiently low to avoid subliming substantially all of said formed whiskers.
Claim 3
Dependent Claim
71 words
The method of claim 1 wherein said composition particles are selected from the group consisting of naphthalene, camphor and carbon dioxide; wherein said substance is selected from the group consisting of nitrogen, dry ammonia, a mixture of hydrogen and dry ammonia, a mixture of nitrogen and dry ammonia, mixture of hydrogen and nitrogen, and a mixture of nitrogen, dry ammoniac and-hydrogen; and wherein said temperature ranges between about 2100"F. and 2750"F.
Claim 4
Dependent Claim
55 words
The method of claim 2 wherein said composition particles are from about 100 to 10,000 times larger than said silicon particles, wherein said compacting step utilizes pressures ranging from about 1,000 to 30,000 psi, and said substance and said silicon compact are reacted for a period of time ranging from about 1 to 48 hours.
Claim 5
Dependent Claim
54 words
The method of claim 2 wherein said composition particles are naphthalene, said substance is nitrogen containing from about 1 to 10 volume percent of a chemical selected from the group consistinq of hydrogen and dry ammonia, and said subliming is accomplished by bakinq said blend at a temperature below the melting point of naphthalene.
Claim 6
Dependent Claim
14 words
The method of claim 4 wherein said silicon particles are blended in powder form.
Claim 7
Dependent Claim
15 words
- The method of claim 2 wherein said blend is compacted into a shaped part.
Claim 8
Dependent Claim
22 words
The method of claim 2 further including the step of converting said compact of silicon nitride whiskers into individual α-silicon nitride whiskers.
Claim 9
Dependent Claim
25 words
The method of claim 2 wherein about 25% to 90% by weight silicon particles are blended with said composition particles to coat said composition particles..
Claim 10
Independent Claim
154 words
A method for producing isotropic composites reinforced by α-silicon nitride whiskers comprising the steps of: (a) blending silicon particles with fugitive composition particles able to sublime without leaving a residue; (b) compacting the blend to a desired shape; (c) subliming said fugitive composition particles from said compacted shape to form a porous silicon precursor compact having said dense shape; (d) reacting said shaped silicon compact with a substance that releases free nitrogen, said reaction occuring at a temperature sufficiently high to convert said compact to an identically shaped porous compact of α-silicon nitride whiskers but sufficiently low to avoid subliming substantially all of said formed whiskers; and (e) impregnating said shaped porous compact of α-silicon nitride whiskers with a material selected from the group consisting of a resin binder, a liquid metal, a colloidal suspension, an ionic solution and at least one gaseous material to form an isotropic composite reinforced by α-silicon nitride whiskers.
Claim 11
Independent Claim
154 words
A method for producing isotropic composites reinforced by α-silicon nitride whiskers comprising the steps of: (a) blending silicon particles with fugitive composition particles able to sublime without leaving a residue; (b) compacting the blend to a desired shape; (c) subliming said fugitive composition particles from said compacted shape to form a porous silicon precursor compact having said dense shape; (d) reacting said shaped silicon compact with a substance that releases free nitrogen, said reaction occuring at a temperature sufficiently high to convert said compact to an identically shaped porous compact of α-silicon nitride whiskers but sufficiently low to avoid subliming substantially all of said formed whiskers; and (e) impregnating said shaped porous compact of α-silicon nitride whiskers with a material selected from the group consisting of a resin binder, a liquid metal, a colloidal suspension, an ionic solution and at least one gaseous material to form an isotropic composite reinforced by α-silicon nitride whiskers.
Claim 12
Dependent Claim
24 words
The method of claim 9 wherein said material is a resin binder selected from the group consisting of acrylic, polyimide, phenolic, epoxy and silicone.
Claim 13
Dependent Claim
17 words
The method of claim 10, further including the step of polymerizing the material in said reinforced composite.
Claim 14
Dependent Claim
52 words
The method of claim 17 wherein said material is a liquid metal selected from the group consisting of aluminum, magnesium, silver and copper, and further including the step of treating said liquid metal with a wetting agent prior to said impregnating step to facilitate the wetting of said whiskers by said metal.
Claim 15
Dependent Claim
45 words
The method of claim 9 wherein said material is an aqueous colloidal suspension selected from the group consisting of silica and alumina, and further including the steps of: (a) drying said impregnated matrix to remove said aqueous phase; and (b) sintering said dried impregnated matrix.
Claim 16
Dependent Claim
42 words
The method of claim 9 wherein said material is an ionic solution selected from the group consisting of aluminum nitrate, nickel chloride and boric acid, and further including the step of decomposing said solution after said impregnating step to form a solid.
Claim 17
Dependent Claim
21 words
The method of claim 9 wherein said material is at least one gaseous material which can be converted to a solid.
Claim 18
Dependent Claim
25 words
The method of claim 15 wherein said gaseous material is selected from the group consisting of silicon tetrachloride, silicon tetrafluoride, ammonia, nitrogen, hydrogen and methane.
Claim 19
Dependent Claim
86 words
The method of claim 16, wherein said gaseous material is a mixture containing at least one gaseous material selected trom the group consisting of silicon tetrachloride and silicon tetrafluoride, and at least one gaseous material selected from the group consisting of dry ammonia, nitrogen and nitrogen with hydrogen, and further including the step of heating said porous shaped compact of α-silicon nitride whiskers whereby said gaseous material mixture reacts to form a dense form of silicon nitride, said dense form being reinforced with α-silicon nitride whiskers.
Claim 20
Independent Claim
139 words
A method for producing individuals-silicon nitride whiskers comprising the steps of: (a) coating silicon particles in powder form with about 5 to 20 weight percent of fugitive composition particles able to sublime without leaving a residue; (b) blending the coated silicon particles with additional fugitive composition particles, said additional fugitive composition particles being larger than said composition particles coating said silicon particles; (c) compacting the blend; (d) subliming said fugitive composition particles from said blend to form a loosely-compacted silicon precursor; (e) reacting said silicon precursor with a substance that releases free nitrogen, said reaction occurring at a temperature sufficiently high to convert said loosely-compacted silicon precursor to loosely-compacted α-silicon nitride whiskers but sufficiently low to avoid subliming substantially all of said whiskers which are formed; and (f) breaking down said loosely-compacted α-silicon nitride whiskers to obtain individual whiskers.
Claim 21
Independent Claim
139 words
A method for producing individuals-silicon nitride whiskers comprising the steps of: (a) coating silicon particles in powder form with about 5 to 20 weight percent of fugitive composition particles able to sublime without leaving a residue; (b) blending the coated silicon particles with additional fugitive composition particles, said additional fugitive composition particles being larger than said composition particles coating said silicon particles; (c) compacting the blend; (d) subliming said fugitive composition particles from said blend to form a loosely-compacted silicon precursor; (e) reacting said silicon precursor with a substance that releases free nitrogen, said reaction occurring at a temperature sufficiently high to convert said loosely-compacted silicon precursor to loosely-compacted α-silicon nitride whiskers but sufficiently low to avoid subliming substantially all of said whiskers which are formed; and (f) breaking down said loosely-compacted α-silicon nitride whiskers to obtain individual whiskers.
Claim 22
Dependent Claim
83 words
The method of claim 18 wherein said coating of said silicon particles is accomplished by ball-milling; wherein said composition is selected from the group consisting of naphthalene, camphor and carbon dioxide; wherein said substance is selected from the group consisting of nitrogen, dry ammonia, a mixture of hydrogen and dry ammonia, a mixture of nitrogen and dry ammonia, a mixture of hydrogen and nitrogen, and a mixture of nitrogen, dry ammonia and hydrogen; and wherein said temperature ranges between about 2100°F. and 2750°F.
Claim 23
Dependent Claim
14 words
The method of claim 19 wherein said temperature ranges between about 2300°F. and 2600-F.
Claim 24
Dependent Claim
37 words
The method of claim 19 wherein said composition is napthalene and wherein said substance is nitrogen containing from about 1 to 10 volume percent of a chemical selected from the group consisting of hydrogen and dry ammonia.
Claim 25
Independent Claim
175 words
A method for producing composite parts using a molding powder reinforced by α-silicon nitride whiskers comprising the steps of: (a) mixing silicon particles in powder form with about 5 to 20 weight percent of fugitive composition particles able to sublime without leaving a residue; (b) treating said mixture of silicon particles and composition particles to coat said silicon particles with said composition particles; (c) blending the coated silicon particles with more of said composition particles; (d) compacting the blend; (e) subliming said composition particles from said blend to form a loosely-compacted silicon precursory (f) reacting said silicon precursor with a substance that releases free nitrogen, said reaction occurring at a temperature sufficiently high to convert said loosely-compacted silicon precursor to loosely-compacted α-silicon nitride whiskers but sufficiently low to avoid subliming substantially all of said whiskers which are formed; (g) breaking down said loosely-compacted α-silicon nitride whiskers to obtain individual whiskers; (h) mixing said α-silicon nitride whiskers with a molding powder; and (i) forming said mixture of whiskers and molding powder into a reinforced composite part.
Claim 26
Independent Claim
175 words
A method for producing composite parts using a molding powder reinforced by α-silicon nitride whiskers comprising the steps of: (a) mixing silicon particles in powder form with about 5 to 20 weight percent of fugitive composition particles able to sublime without leaving a residue; (b) treating said mixture of silicon particles and composition particles to coat said silicon particles with said composition particles; (c) blending the coated silicon particles with more of said composition particles; (d) compacting the blend; (e) subliming said composition particles from said blend to form a loosely-compacted silicon precursory (f) reacting said silicon precursor with a substance that releases free nitrogen, said reaction occurring at a temperature sufficiently high to convert said loosely-compacted silicon precursor to loosely-compacted α-silicon nitride whiskers but sufficiently low to avoid subliming substantially all of said whiskers which are formed; (g) breaking down said loosely-compacted α-silicon nitride whiskers to obtain individual whiskers; (h) mixing said α-silicon nitride whiskers with a molding powder; and (i) forming said mixture of whiskers and molding powder into a reinforced composite part.
Claim 27
Dependent Claim
26 words
The method of claim 22 wherein said molding powder is selected from the group consisting of metal molding powder, ceramic molding powder and resin molding powder.
References Cited (Backward Citations)
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