US4710348A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for forming metal-ceramic composites
Assignee: Lockheed Martin Corp
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Filing: 1986-12-19
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Granted: 1987-12-01
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Expires: 2006-12-19
Abstract
Abstract A method is taught for the in-situ precipitation of ceramic materials in a metal matrix. By means of the solvent assisted reaction, metal-ceramic composites having highly superior properties may be obtained. The invention involves the reaction of the ceramic forming constituents in a metal solvent medium to provide very finely-dispersed ceramic particles in the metal matrix. Exemplary materials include titanium diboride in an aluminum matrix.
Inventors
- 👤 John M. Brupbacher
- 👤 Leontios Christodoulou
- 👤 Dennis C. Nagle
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 03:45
CPC Classifications
C; C22; C22C; C22C1/00; C22C1/04; C22C1/05; C22C1/051; B; B22; B22F; B22F3/00; B22F3/23; B22F9/00; B22F9/02; B22F9/14; B23; B23K; B23K35/00; B23K35/22; B23K35/24; B23K35/32; B23K35/327; B23K35/40; B82; B82Y; B82Y30/00; C22C1/10; C22C1/1005; C22C1/1015; C22C1/1036; C22C1/1047; C22C1/1052; C22C1/1068; C22C29/00; C22C32/00; C22C32/0047; C22C32/0078; C22C47/00; C22C47/02; C22C47/06; C22C47/08; C22C49/00; C22C49/14; Y; Y10; Y10T; Y10T428/00; Y10T428/12; Y10T428/12486
Claims Analysis
Total Claims: 57
Claim 1
Independent Claim
100 words
A method for the production of metal-ceramic composite materials containing a ceramic phase, said method comprising precipitating at least one ceramic material in a metal matrix by contacting reactive ceramic forming constituents, in the presence of a non-reactive solvent matrix metal in which said ceramic forming constituents are more soluble than said ceramic phase, at a temperature at which sufficient diffusion of said constituents into said solvent matrix metal occurs to cause reaction of said reactive ceramic forming constituents raising the temperature above the melting temperature of the matrix metal to precipitate said ceramic phase in said solvent matrix metal.
Claim 2
Independent Claim
100 words
A method for the production of metal-ceramic composite materials containing a ceramic phase, said method comprising precipitating at least one ceramic material in a metal matrix by contacting reactive ceramic forming constituents, in the presence of a non-reactive solvent matrix metal in which said ceramic forming constituents are more soluble than said ceramic phase, at a temperature at which sufficient diffusion of said constituents into said solvent matrix metal occurs to cause reaction of said reactive ceramic forming constituents raising the temperature above the melting temperature of the matrix metal to precipitate said ceramic phase in said solvent matrix metal.
Claim 3
Dependent Claim
14 words
A method as set forth in claim 1, wherein the reaction is substantially complete.
Claim 4
Dependent Claim
26 words
A method as set forth in claim 1, wherein the reactive ceramic forming constituents and the solvent matrix metal are each provided as the individual elements.
Claim 5
Dependent Claim
14 words
A method as set forth in claim 1, wherein the ceramic phase is particulate.
Claim 6
Dependent Claim
16 words
A method as set forth in claim 4, wherein the particulate ceramic phase is precipitated in-situ.
Claim 7
Dependent Claim
23 words
A method as set forth in claim 1, wherein the ceramic-forming constituents are each provided as an alloy of said solvent matrix metal.
Claim 8
Dependent Claim
17 words
A method as set forth in claim 5, wherein the particulate ceramic phase is submicron in size.
Claim 9
Dependent Claim
24 words
A method as set forth in claim 6, wherein the ceramic forming constituents in the solvent matrix metal are contacted in substantially stoichiometric proportions.
Claim 10
Dependent Claim
37 words
A method as set forth in claim 1, wherein at least one ceramic forming constituent is provided as an alloy of the solvent matrix metal, and the other ceramic forming constituents are provided as the individual elements.
Claim 11
Independent Claim
94 words
A method for precipitation of a ceramic phase in a metallic matrix, said method comprising the steps of: (a) preparing a mixture of reactive ceramic forming constituents and a substantially non-reactive solvent matrix metal in which said ceramic forming constituents are more soluble than said ceramic phase; (b) heating the mixture to a reaction initiation temperature approximating the melting point of the solvent matrix metal to initiate an exothermic reaction; (c) permitting said exothermic reaction to further heat the mixture and to form a uniform distribution of ceramic particles; and (d) recovering a product.
Claim 12
Independent Claim
94 words
A method for precipitation of a ceramic phase in a metallic matrix, said method comprising the steps of: (a) preparing a mixture of reactive ceramic forming constituents and a substantially non-reactive solvent matrix metal in which said ceramic forming constituents are more soluble than said ceramic phase; (b) heating the mixture to a reaction initiation temperature approximating the melting point of the solvent matrix metal to initiate an exothermic reaction; (c) permitting said exothermic reaction to further heat the mixture and to form a uniform distribution of ceramic particles; and (d) recovering a product.
Claim 13
Dependent Claim
30 words
A method as set forth in claim 10, wherein at least one ceramic forming constituent is selected from transition metals of the third to sixth groups of the Periodic Table.
Claim 14
Dependent Claim
31 words
A method as set forth in claim 10, wherein at least one ceramic forming constituent is selected from aluminum, titanium, silicon, boron, carbon, sulfur, germanium, molybdenum, tungsten, vanadium, zirconium, and chromium.
Claim 15
Dependent Claim
43 words
A method as set forth in claim 12 wherein said solvent matrix metal is selected from aluminum, gallium, nickel, titanium, copper, vanadium, chromium, manganese, cobalt, iron, silicon, germanium, silver, gold, platinum, palladium, rhodium, ruthenium, magnesium, lead, zinc, tin, and alloys of such metals.
Claim 16
Dependent Claim
22 words
A method as set forth in claim 10, wherein the ceramic forming constituents and the solvent metal are provided as individual elements.
Claim 17
Dependent Claim
17 words
A method as set forth in claim 14, wherein said reaction takes place in the liquid state.
Claim 18
Dependent Claim
31 words
A method as set forth in claim 15, wherein the solvent matrix metal is selected from aluminum, zinc, magnesium, copper, lead, nickel, chromium, iron, titanium, cobalt, and alloys of such metals.
Claim 19
Dependent Claim
29 words
A method as set forth in claim 16, wherein at least one ceramic forming constituent is selected from aluminum, silicon, titanium, hafnium, tantalum, zirconium, magnesium, vanadium, nickel, and tungsten.
Claim 20
Dependent Claim
25 words
A method as set forth in claim 17, wherein at least one other ceramic forming constituent is selected from aluminum, boron, silicon, nitrogen, and carbon.
Claim 21
Dependent Claim
24 words
A method as set forth in claim 10, wherein the ceramic forming constituents are each provided as an alloy of the solvent matrix metal.
Claim 22
Dependent Claim
31 words
A method as set forth in claim 19, wherein said solvent matrix metal is selected from aluminum, zinc, magnesium, copper, lead, nickel, chromium, iron, titanium, cobalt, and alloys of such metals.
Claim 23
Dependent Claim
24 words
A method as set forth in claim 20, wherein said ceramic forming constituents are each selected from titanium, zirconium, magnesium, boron, silicon, and carbon.
Claim 24
Dependent Claim
36 words
A method as set forth in claim 10, wherein at least one ceramic forming constituent is provided as an individual element, and the other ceramic forming constituents are provided as alloys of the solvent matrix metal.
Claim 25
Dependent Claim
30 words
A method as set forth in claim 22, wherein said solvent matrix metal is selected from aluminum, zinc, magnesium, copper, nickel, chromium, iron, titanium, cobalt, and alloys of such metals.
Claim 26
Dependent Claim
25 words
A method as set forth in claim 23, wherein said ceramic forming constituents are each selected from aluminum, titanium, zirconium, magnesium, boron, silicon, and carbon.
Claim 27
Independent Claim
125 words
A method for the uniform dispersion of ceramic dispersoids in a metal matrix, said method comprising forming a reaction mixture of reactive ceramic forming constituents in the presence of at least two solvent metals in which ceramic forming constituents are more soluble than said ceramic dispersoids, raising the temperature of said reaction mixture to a temperature at which sufficient diffusion of the ceramic forming constituents into the lowest melting solvent metal occurs to initiate reaction of said constituents, whereby the exothermic heat of reaction of said constituents causes the temperature of the reaction mixture to exceed the melting point of the matrix of the higher melting metal permitting uniform dispersion of said ceramic dispersoid in a matrix of higher melting metal or an alloy thereof.
Claim 28
Independent Claim
125 words
A method for the uniform dispersion of ceramic dispersoids in a metal matrix, said method comprising forming a reaction mixture of reactive ceramic forming constituents in the presence of at least two solvent metals in which ceramic forming constituents are more soluble than said ceramic dispersoids, raising the temperature of said reaction mixture to a temperature at which sufficient diffusion of the ceramic forming constituents into the lowest melting solvent metal occurs to initiate reaction of said constituents, whereby the exothermic heat of reaction of said constituents causes the temperature of the reaction mixture to exceed the melting point of the matrix of the higher melting metal permitting uniform dispersion of said ceramic dispersoid in a matrix of higher melting metal or an alloy thereof.
Claim 29
Dependent Claim
26 words
A method as set forth in claim 25, wherein said lowest melting solvent metal is present as a minor proportion of a higher melting solvent metal.
Claim 30
Dependent Claim
25 words
A method as set forth in claim 26, wherein said higher melting solvent metal is selected from cobalt, chromium, nickel, titanium, vanadium, iron, and silicon.
Claim 31
Dependent Claim
24 words
A method as set forth in claim 27, wherein said lowest melting solvent metal is selected from aluminum, copper, tin, zinc, lead, and magnesium.
Claim 32
Independent Claim
103 words
A method for the in-situ precipitation of at least one intermetallic material in a metallic matrix, said method comprising the steps of: (a) preparing a mixture of reactive intermetallic forming constituents and a non-reactive solvent matrix metal in which said intermetallic forming constituents are more soluble than said intermetallic material; (b) heating the mixture to a reaction initiation temperature approximating the melting point of the solvent matrix metal; (c) permitting the resultant exothermic reaction to raise the temperature of said mixture to a temperature exceeding the melting point of the matrix metal and to consume intermetallic forming constituents; and (d) recovering a product.
Claim 33
Independent Claim
103 words
A method for the in-situ precipitation of at least one intermetallic material in a metallic matrix, said method comprising the steps of: (a) preparing a mixture of reactive intermetallic forming constituents and a non-reactive solvent matrix metal in which said intermetallic forming constituents are more soluble than said intermetallic material; (b) heating the mixture to a reaction initiation temperature approximating the melting point of the solvent matrix metal; (c) permitting the resultant exothermic reaction to raise the temperature of said mixture to a temperature exceeding the melting point of the matrix metal and to consume intermetallic forming constituents; and (d) recovering a product.
Claim 34
Dependent Claim
32 words
A method as set forth in claim 29, wherein at least one intermetallic forming constituent is selected from aluminum, titanium, silicon, nickel, vanadium, molybdenum, niobium, thorium, tungsten, zirconium, yttrium, lithium, and germanium.
Claim 35
Dependent Claim
42 words
A method as set forth in claim 30 wherein said solvent metal is selected from aluminum, gallium, nickel, titanium, copper, vanadium, chromium, manganese, cobalt, iron, silicon, germanium, silver, gold, platinum, palladium, rhodium, ruthenium, magnesium, lead, zinc, tin, and alloys of such metals.
Claim 36
Independent Claim
127 words
A method for the in-situ precipitation of dispersoid particles of at least one intermetallic material and at least one ceramic material in a metal matrix, said method comprising the steps of: (a) preparing a mixture of reactive intermetallic and ceramic forming constituents and a substantially non-reactive solvent matrix metal in which said intermetallic and ceramic forming constituents are more soluble than said intermetallic material and said at least one ceramic material, respectively; (b) heating the mixture to a reaction initiation temperature approximating the melting point of the solvent matrix metal; (c) permitting the resultant exothermic reaction to raise the temperature of the mixture to a temperature exceeding the melting point of the matrix metal and to consume intermetallic and ceramic forming constituents; and (d) recovering a product.
Claim 37
Independent Claim
127 words
A method for the in-situ precipitation of dispersoid particles of at least one intermetallic material and at least one ceramic material in a metal matrix, said method comprising the steps of: (a) preparing a mixture of reactive intermetallic and ceramic forming constituents and a substantially non-reactive solvent matrix metal in which said intermetallic and ceramic forming constituents are more soluble than said intermetallic material and said at least one ceramic material, respectively; (b) heating the mixture to a reaction initiation temperature approximating the melting point of the solvent matrix metal; (c) permitting the resultant exothermic reaction to raise the temperature of the mixture to a temperature exceeding the melting point of the matrix metal and to consume intermetallic and ceramic forming constituents; and (d) recovering a product.
Claim 38
Dependent Claim
46 words
A method as set forth in claim 32, wherein at least one intermetallic forming constituent and at least one ceramic forming constituent are selected from the group consisting of aluminum, titanium, silicon, nickel, vanadium, molybdenum, niobium, thorium, tungsten, zirconium, yttrium, lithium, germanium, boron, carbon, and nitrogen.
Claim 39
Dependent Claim
42 words
A method as set forth in claim 33 wherein said solvent metal is selected from aluminum, gallium, nickel, titanium, copper, vanadium, chromium, manganese, cobalt, iron, silicon, germanium, silver, gold, platinum, palladium, rhodium, ruthenium, magnesium, lead, zinc, tin, and alloys of such metals.
Claim 40
Independent Claim
105 words
A method for the production of metal-ceramic composite materials containing a ceramic phase, said method comprising precipitating at least one ceramic material in a metal matrix by contacting reactive ceramic forming constituents, in the presence of a non-reactive solvent matrix metal in which said ceramic forming constituents are more soluble than said ceramic phase, at a temperature at which sufficient diffusion of said constituents into said solvent matrix metal occurs to cause reaction of said reactive ceramic forming constituents raising the temperature above the melting temperature of the matrix metal to precipitate a substantially uniform distribution of said ceramic phase in said solvent matrix metal.
Claim 41
Independent Claim
105 words
A method for the production of metal-ceramic composite materials containing a ceramic phase, said method comprising precipitating at least one ceramic material in a metal matrix by contacting reactive ceramic forming constituents, in the presence of a non-reactive solvent matrix metal in which said ceramic forming constituents are more soluble than said ceramic phase, at a temperature at which sufficient diffusion of said constituents into said solvent matrix metal occurs to cause reaction of said reactive ceramic forming constituents raising the temperature above the melting temperature of the matrix metal to precipitate a substantially uniform distribution of said ceramic phase in said solvent matrix metal.
Claim 42
Independent Claim
108 words
A method for the in-situ precipitation of a substantially uniform distibution of at least one intermetallic material in a metallic matrix, said method comprising the steps of: (a) preparing a mixture of reactive intermetallic forming constituents and a non-reactive solvent matrix metal in which said intermetallic forming constituents are more soluble than said intermetallic material; (b) heating the mixture to a reaction initiation temperature approximating the melting point of the solvent matrix metal; (c) permitting the resultant exothermic reaction to raise the temperature of said mixture to a temperature exceeding the melting point of the matrix metal and to consume intermetallic forming constituents; and (d) recovering a product.
Claim 43
Independent Claim
108 words
A method for the in-situ precipitation of a substantially uniform distibution of at least one intermetallic material in a metallic matrix, said method comprising the steps of: (a) preparing a mixture of reactive intermetallic forming constituents and a non-reactive solvent matrix metal in which said intermetallic forming constituents are more soluble than said intermetallic material; (b) heating the mixture to a reaction initiation temperature approximating the melting point of the solvent matrix metal; (c) permitting the resultant exothermic reaction to raise the temperature of said mixture to a temperature exceeding the melting point of the matrix metal and to consume intermetallic forming constituents; and (d) recovering a product.
Claim 44
Independent Claim
132 words
A method for the in-situ precipitation of a substantially uniform distribution of dispersoid particles of at least one intermetallic material and at least one ceramic material in a metal matrix, said method comprising the steps of: (a) preparing a mixture of reactive intermetallic and ceramic forming constituents and a substantially non-reactive solvent matrix metal in which said intermetallic and ceramic forming constituents are more soluble than said intermetallic material and said at least one ceramic material, respectively; (b) heating the mixture to a reaction initiation temperature approximating the melting point of the solvent matrix metal; (c) permitting the resultant exothermic reaction to raise the temperature of the mixture to a temperature exceeding the melting point of the matrix metal and to consume intermetallic and ceramic forming constituents; and (d) recovering a product.
Claim 45
Independent Claim
132 words
A method for the in-situ precipitation of a substantially uniform distribution of dispersoid particles of at least one intermetallic material and at least one ceramic material in a metal matrix, said method comprising the steps of: (a) preparing a mixture of reactive intermetallic and ceramic forming constituents and a substantially non-reactive solvent matrix metal in which said intermetallic and ceramic forming constituents are more soluble than said intermetallic material and said at least one ceramic material, respectively; (b) heating the mixture to a reaction initiation temperature approximating the melting point of the solvent matrix metal; (c) permitting the resultant exothermic reaction to raise the temperature of the mixture to a temperature exceeding the melting point of the matrix metal and to consume intermetallic and ceramic forming constituents; and (d) recovering a product.
Claim 46
Independent Claim
112 words
A method for the production of metal-ceramic composite materials containing a ceramic phase, said method comprising precipitating at least one ceramic material in a metal matrix by contacting reactive ceramic forming constituents, in the presence of a non-reactive solvent matrix metal in which said ceramic forming constituents are more soluble than said ceramic phase, at a temperature at which sufficient diffusion of more than a localized portion of said constituents into said solvent matrix metal occurs to cause reaction of said reactive ceramic forming constituents raising the temperature of said reactive ceramic forming constituents above the melting temperature of the matrix metal to precipitate said ceramic phase in said solvent matrix metal.
Claim 47
Independent Claim
112 words
A method for the production of metal-ceramic composite materials containing a ceramic phase, said method comprising precipitating at least one ceramic material in a metal matrix by contacting reactive ceramic forming constituents, in the presence of a non-reactive solvent matrix metal in which said ceramic forming constituents are more soluble than said ceramic phase, at a temperature at which sufficient diffusion of more than a localized portion of said constituents into said solvent matrix metal occurs to cause reaction of said reactive ceramic forming constituents raising the temperature of said reactive ceramic forming constituents above the melting temperature of the matrix metal to precipitate said ceramic phase in said solvent matrix metal.
Claim 48
Independent Claim
96 words
A method for precipitation of a ceramic phase in a metallic matrix, said method comprising the steps of: (a) preparing a mixture of reactive ceramic forming constituents and a substantially non-reactive solvent matrix metal in which said ceramic forming constituents are more soluble than said ceramic phase; (b) heating more than a localized portion of the mixture to a reaction initiation temperature approximating the melting point of the solvent matrix metal to initiate an exothermic reaction; (c) permitting said exothermic reaction to further heat the mixture and to form ceramic particles; and (d) recovering a product.
Claim 49
Independent Claim
96 words
A method for precipitation of a ceramic phase in a metallic matrix, said method comprising the steps of: (a) preparing a mixture of reactive ceramic forming constituents and a substantially non-reactive solvent matrix metal in which said ceramic forming constituents are more soluble than said ceramic phase; (b) heating more than a localized portion of the mixture to a reaction initiation temperature approximating the melting point of the solvent matrix metal to initiate an exothermic reaction; (c) permitting said exothermic reaction to further heat the mixture and to form ceramic particles; and (d) recovering a product.
Claim 50
Independent Claim
133 words
A method for the substantially uniform dispersion of ceramic dispersoids in a metal matrix, said method comprising forming a reaction mixture of reactive ceramic forming constituents in the presence of at least two solvent metals in which ceramic forming constituents are more soluble than said ceramic dispersoids, raising the temperature of more than a localized portion of said reaction mixture to a temperature at which sufficient diffusion of the ceramic forming constituents into the lowest melting solvent metal occurs to initiate reaction of said constituents, whereby the exothermic heat of reaction of said constituents causes the temperature of the reaction mixture to exceed the melting point of the matrix of the higher melting metal permitting substantially uniform dispersion of said ceramic dispersoid in a matrix of higher melting metal or an alloy thereof.
Claim 51
Independent Claim
133 words
A method for the substantially uniform dispersion of ceramic dispersoids in a metal matrix, said method comprising forming a reaction mixture of reactive ceramic forming constituents in the presence of at least two solvent metals in which ceramic forming constituents are more soluble than said ceramic dispersoids, raising the temperature of more than a localized portion of said reaction mixture to a temperature at which sufficient diffusion of the ceramic forming constituents into the lowest melting solvent metal occurs to initiate reaction of said constituents, whereby the exothermic heat of reaction of said constituents causes the temperature of the reaction mixture to exceed the melting point of the matrix of the higher melting metal permitting substantially uniform dispersion of said ceramic dispersoid in a matrix of higher melting metal or an alloy thereof.
Claim 52
Independent Claim
109 words
A method for the in-situ precipitation of at least one intermetallic material in a metallic matrix, said method comprising the steps of: (a) preparing a mixture of reactive intermetallic forming constituents and a non-reactive solvent matrix metal in which said intermetallic forming constituents are more soluble than said intermetallic material; (b) heating more than a localized portion of the mixture to a reaction initiation temperature approximating the melting point of the solvent matrix metal; (c) permitting the resultant exothermic reaction to raise the temperature of said mixture to a temperature exceeding the melting point of the matrix metal and to consume intermetallic forming constituents; and (d) recovering a product.
Claim 53
Independent Claim
109 words
A method for the in-situ precipitation of at least one intermetallic material in a metallic matrix, said method comprising the steps of: (a) preparing a mixture of reactive intermetallic forming constituents and a non-reactive solvent matrix metal in which said intermetallic forming constituents are more soluble than said intermetallic material; (b) heating more than a localized portion of the mixture to a reaction initiation temperature approximating the melting point of the solvent matrix metal; (c) permitting the resultant exothermic reaction to raise the temperature of said mixture to a temperature exceeding the melting point of the matrix metal and to consume intermetallic forming constituents; and (d) recovering a product.
Claim 54
Independent Claim
133 words
A method for the in-situ precipitation of dispersoid particles of at least one intermetallic material and at least one ceramic material in a metal matrix, said method comprising the steps of: (a) preparing a mixture of reactive intermetallic and ceramic forming constituents and a substantially non-reactive solvent matrix metal in which said intermetallic and ceramic forming constituents are more soluble than said intermetallic material and said at least one ceramic material, respectively; (b) heating more than a localized portion of the mixture to a reaction initiation temperature approximating the melting point of the solvent matrix metal; (c) permitting the resultant exothermic reaction to raise the temperature of the mixture to a temperature exceeding the melting point of the matrix metal and to consume intermetallic and ceramic forming constituents; and (d) recovering a product.
Claim 55
Independent Claim
133 words
A method for the in-situ precipitation of dispersoid particles of at least one intermetallic material and at least one ceramic material in a metal matrix, said method comprising the steps of: (a) preparing a mixture of reactive intermetallic and ceramic forming constituents and a substantially non-reactive solvent matrix metal in which said intermetallic and ceramic forming constituents are more soluble than said intermetallic material and said at least one ceramic material, respectively; (b) heating more than a localized portion of the mixture to a reaction initiation temperature approximating the melting point of the solvent matrix metal; (c) permitting the resultant exothermic reaction to raise the temperature of the mixture to a temperature exceeding the melting point of the matrix metal and to consume intermetallic and ceramic forming constituents; and (d) recovering a product.
Claim 56
Independent Claim
90 words
A method for precipitation of a ceramic phase in a metallic matrix, said method comprising the steps of: (a) preparing a mixture of reactive ceramic forming constituents and a substantially non-reactive solvent matrix metal in which said ceramic forming constituents are more soluble than said ceramic phase; (b) heating the mixture to a reaction initiation temperature approximating the melting point of the solvent matrix metal to initiate an exothermic reaction; (c) permitting said exothermic reaction to further heat the mixture and to form ceramic particles; and (d) recovering a product.
Claim 57
Independent Claim
90 words
A method for precipitation of a ceramic phase in a metallic matrix, said method comprising the steps of: (a) preparing a mixture of reactive ceramic forming constituents and a substantially non-reactive solvent matrix metal in which said ceramic forming constituents are more soluble than said ceramic phase; (b) heating the mixture to a reaction initiation temperature approximating the melting point of the solvent matrix metal to initiate an exothermic reaction; (c) permitting said exothermic reaction to further heat the mixture and to form ceramic particles; and (d) recovering a product.
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USPTO Annuity & Maintenance Windows
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| 3.5 Years (Year 4) | 1990-11-30 | 1991-06-01 | 1991-12-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-11-30 | 1995-06-01 | 1995-12-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-11-30 | 1999-06-01 | 1999-12-01 | $7700.00 | Window Closed / Lapsed |