Patent US5154779A successfully refreshed from Google Patents.
US5154779A
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Method of nitriding, carburizing, or oxidizing refractory metal articles using microwaves
Assignee: Lockheed Martin Energy Systems Inc
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Filing: 1992-02-18
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Granted: 1992-10-13
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Expires: 2012-02-18
Abstract
Abstract A method of nitriding an article of refractory-nitride-forming metal or metalloids. A consolidated metal or metalloid article is placed inside a microwave oven and nitrogen containing gas is introduced into the microwave oven. The metal or metalloid article is heated to a temperature sufficient to react the metal or metalloid with the nitrogen by applying a microwave energy within the microwave oven. The metal or metalloid article is maintained at that temperature for a period of time sufficient to convert the article of metal or metalloid to an article of refractory nitride. in addition, a method of applying a coating, such as a coating of an oxide, a carbide, or a carbo-nitride, to an article of metal or metalloid by microwave heating.
Inventors
- 👤 Cressie E. Holcombe
- 👤 Norman L. Dykes
- 👤 Terry N. Tiegs
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 07:07
CPC Classifications
C; C23; C23C; C23C8/00; C23C8/06; C23C8/08; C23C8/24; H; H05; H05B; H05B6/00; H05B6/64
Claims Analysis
Total Claims: 49
Claim 1
Independent Claim
142 words
A method of nitriding an article of refractory-nitride-forming metal or metalloid comprising the following steps: Step 1) providing an article of metal or metalloid having an intimately contacting enwrapment of a ceramic insulating material within a microwave oven; Step 2) introducing a nitrogen containing atmosphere within said microwave oven, said nitrogen containing atmosphere comprises gases selected from the group consisting of ammonia, nitrogen and mixtures thereof; Step 3) heating said article of metal or metalloid in said nitrogen containing atmosphere within said microwave oven to a temperature sufficient to react with said article of metal or metalloid with said nitrogen by applying a microwave energy within said microwave oven; and Step 4) maintaining said article of metal or metalloid at said temperature for a period of time sufficient to convert said article of metal of metalloid to an article or refractory nitride.
Claim 2
Independent Claim
142 words
A method of nitriding an article of refractory-nitride-forming metal or metalloid comprising the following steps: Step 1) providing an article of metal or metalloid having an intimately contacting enwrapment of a ceramic insulating material within a microwave oven; Step 2) introducing a nitrogen containing atmosphere within said microwave oven, said nitrogen containing atmosphere comprises gases selected from the group consisting of ammonia, nitrogen and mixtures thereof; Step 3) heating said article of metal or metalloid in said nitrogen containing atmosphere within said microwave oven to a temperature sufficient to react with said article of metal or metalloid with said nitrogen by applying a microwave energy within said microwave oven; and Step 4) maintaining said article of metal or metalloid at said temperature for a period of time sufficient to convert said article of metal of metalloid to an article or refractory nitride.
Claim 3
Dependent Claim
45 words
A method in accordance with claim 1 wherein said article comprises a metal selected from the group consisting of titanium, tantalum, hafnium, zirconium, niobium and mixtures thereof or change said article comprises a metalloid selected from the group consisting of silicon, boron, and mixtures thereof.
Claim 4
Dependent Claim
47 words
A method in accordance with claim 2 wherein said article in Step 1 is silicon, said period of time in Step 4 is about 12 hours, said temperature in Step 3 is about 1350° C. in order to obtain approximately 95% conversion of silicon to silicon nitride.
Claim 5
Dependent Claim
46 words
A method in accordance with claim 1 wherein said article comprises materials selected from the group consisting of silicon, carbon, iron, and mixtures thereof, and said ceramic insulating material comprises materials selected from the group consisting of yttria, alumina, iron oxide, silicon nitride, and mixtures thereof.
Claim 6
Dependent Claim
22 words
A method in accordance with claim 1 wherein said microwave energy in Step 3 is generated by a 2.45 GHz microwave oven.
Claim 7
Dependent Claim
61 words
A method in accordance with claim 1 wherein in step 1 said article of metal or metalloid is enwrapped in a ceramic aggregate of granular material which further is contained in a refractory ceramic container, said granular material having an average particle size ranging from -4 to +100 mesh and being in intimate contact with said article of metal or metalloid.
Claim 8
Dependent Claim
19 words
A method in accordance with claim 1 wherein said temperature in Step 3 is greater than 1,000 degrees centigrade.
Claim 9
Dependent Claim
24 words
A method in accordance with claim 1 wherein said article of refractory nitride has a density up to and including 85% of theoretical density.
Claim 10
Dependent Claim
39 words
A method in accordance with claim 1 wherein said nitrogen containing atmosphere contains gases selected from the group consisting of ammonia, nitrogen and mixtures thereof and gases selected from the group consisting of hydrogen, inert gases and mixtures thereof.
Claim 11
Dependent Claim
23 words
A method in accordance with claim 9 wherein said inert gases are selected from the group consisting of argon, helium and mixtures thereof.
Claim 12
Independent Claim
146 words
A method of providing a metal nitride coating on an article of metal or metalloid comprising the following steps: Step 1) providing an article of metal or metalloid having an intimately contacting enwrapment of a ceramic insulating material within a microwave oven; Step 2) introducing a nitrogen containing atmosphere within said microwave oven, said nitrogen containing atmosphere comprises gases selected from the group consisting of ammonia, nitrogen and mixtures, thereof; Step 3) heating said article of metal of metalloid in said nitrogen containing atmosphere within said microwave oven to a temperature sufficient to react with said article of metal or metalloid with said nitrogen by applying a microwave energy within said microwave oven; and Step 4) maintaining said article of metal or metalloid at said temperature for a period of time sufficient to form a coating of nitride on said article of refractory metal or metalloid.
Claim 13
Independent Claim
146 words
A method of providing a metal nitride coating on an article of metal or metalloid comprising the following steps: Step 1) providing an article of metal or metalloid having an intimately contacting enwrapment of a ceramic insulating material within a microwave oven; Step 2) introducing a nitrogen containing atmosphere within said microwave oven, said nitrogen containing atmosphere comprises gases selected from the group consisting of ammonia, nitrogen and mixtures, thereof; Step 3) heating said article of metal of metalloid in said nitrogen containing atmosphere within said microwave oven to a temperature sufficient to react with said article of metal or metalloid with said nitrogen by applying a microwave energy within said microwave oven; and Step 4) maintaining said article of metal or metalloid at said temperature for a period of time sufficient to form a coating of nitride on said article of refractory metal or metalloid.
Claim 14
Dependent Claim
44 words
A method in accordance with claim 11 wherein said article comprises a metal selected from the group consisting of titanium, tantalum, hafnium, zirconium, niobium and mixtures thereof or said article comprises a metalloid selected from the group consisting of silicon, boron, and mixtures thereof.
Claim 15
Dependent Claim
46 words
A method in accordance with claim 11 wherein said article comprises materials selected from the group consisting of silicon, carbon, iron, and mixtures thereof, and said ceramic insulating material comprises materials selected from the group consisting of yttria, alumina, iron oxide, silicon nitride, and mixtures thereof.
Claim 16
Dependent Claim
22 words
A method in accordance with claim 11 wherein said microwave energy in Step 3 is generated by a 2.45 GHz microwave oven.
Claim 17
Dependent Claim
61 words
A method in accordance with claim 11 wherein in step 1 said article of metal or metalloid is enwrapped in a ceramic aggregate of granular material which further is contained in a refractory ceramic container, said granular material having an average particle size ranging from -4 to +100 mesh and being in intimate contact with said article of metal or metalloid.
Claim 18
Dependent Claim
19 words
A method in accordance with claim 11, wherein said temperature in Step 3 is greater than 1,000 degrees centigrade.
Claim 19
Dependent Claim
20 words
A method in accordance with claim 11 wherein said period of time in Step 4 is less than 150 hours.
Claim 20
Dependent Claim
39 words
A method in accordance with claim 11 wherein said nitrogen containing atmosphere contains gases selected from the group consisting of ammonia, nitrogen and mixtures thereof and gases selected from the group consisting of hydrogen, inert gases and mixtures thereof.
Claim 21
Dependent Claim
23 words
A method in accordance with claim 18 wherein said inert gases are selected from the group consisting of argon, helium and mixtures thereof.
Claim 22
Independent Claim
136 words
A method of providing an oxide coating on an article of refractory metal or metalloid comprising the following steps: Step 1) providing an article of metal or metalloid having an intimately contacting enwrapment of a ceramic insulating material within a microwave oven; Step 2) introducing an oxygen containing atmosphere within said microwave oven, said oxygen containing atmosphere being comprised of air; Step 3) heating said article of metal or metalloid in said atmosphere within said microwave oven to a temperature sufficient to react said oxygen in said atmosphere with said article of metal or metalloid by applying a microwave energy within said microwave oven; and Step 4) maintaining said article of metal or metalloid at said temperature for a period of time sufficient to form a coating of oxide on said article of metal or metalloid.
Claim 23
Independent Claim
136 words
A method of providing an oxide coating on an article of refractory metal or metalloid comprising the following steps: Step 1) providing an article of metal or metalloid having an intimately contacting enwrapment of a ceramic insulating material within a microwave oven; Step 2) introducing an oxygen containing atmosphere within said microwave oven, said oxygen containing atmosphere being comprised of air; Step 3) heating said article of metal or metalloid in said atmosphere within said microwave oven to a temperature sufficient to react said oxygen in said atmosphere with said article of metal or metalloid by applying a microwave energy within said microwave oven; and Step 4) maintaining said article of metal or metalloid at said temperature for a period of time sufficient to form a coating of oxide on said article of metal or metalloid.
Claim 24
Dependent Claim
52 words
A method in accordance with claim 20 wherein said article comprises a refractory metal selected from the group consisting of titanium, yttrium, scandium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, hafnium, aluminum, chromium, uranium, thorium, zirconium, and mixtures thereof or said article comprises silicon.
Claim 25
Dependent Claim
22 words
A method in accordance with claim 20 wherein said microwave energy in Step 3 is generated by a 2.45 GHz microwave oven.
Claim 26
Dependent Claim
61 words
A method in accordance with claim 20 wherein in step 1 said article of metal or metalloid is enwrapped in a ceramic aggregate of granular material which further is contained in a refractory ceramic container, said granular material having an average particle size ranging from -4 to +100 mesh and being in intimate contact with said article of metal or metalloid.
Claim 27
Dependent Claim
24 words
A method in accordance with claim 20 wherein said atmosphere in Step 2 is provided by a flow of air into said microwave oven.
Claim 28
Independent Claim
145 words
A method of providing a carbide coating on an article of metal or metalloid comprising the following steps: Step 1) providing an article of metal or metalloid having an intimately contacting enwrapment of a ceramic insulating material within a microwave oven; Step 2) introducing a carbon containing atmosphere within said microwave oven, said carbon containing atmosphere comprises gases selected from the group consisting of methane, acetylene, butane and mixtures thereof; Step 3) heating said article of metal or metalloid in said atmosphere within said microwave oven to a temperature sufficient to react said methane in said atmosphere with said article of metal or metalloid by applying a microwave energy with said microwave oven; and Step 4) maintaining said article of metal or metalloid at said temperature for a period of time sufficient to form a coating of carbide on said article of metal or metalloid.
Claim 29
Independent Claim
145 words
A method of providing a carbide coating on an article of metal or metalloid comprising the following steps: Step 1) providing an article of metal or metalloid having an intimately contacting enwrapment of a ceramic insulating material within a microwave oven; Step 2) introducing a carbon containing atmosphere within said microwave oven, said carbon containing atmosphere comprises gases selected from the group consisting of methane, acetylene, butane and mixtures thereof; Step 3) heating said article of metal or metalloid in said atmosphere within said microwave oven to a temperature sufficient to react said methane in said atmosphere with said article of metal or metalloid by applying a microwave energy with said microwave oven; and Step 4) maintaining said article of metal or metalloid at said temperature for a period of time sufficient to form a coating of carbide on said article of metal or metalloid.
Claim 30
Dependent Claim
48 words
A method in accordance with claim 25 wherein said article comprise a metal selected from the group consisting of titanium, tungsten, hafnium, tantalum, vanadium, chromium, molybdenum, zirconium, niobium and mixtures thereof or said article comprises a metalloid selected from the group consisting of silicon, boron, and mixtures thereof.
Claim 31
Dependent Claim
40 words
A method in accordance with claim 25 wherein said carbon containing atmosphere contains gases selected from the group consisting of methane, acetylene, butane and mixtures thereof and gases selected from the group consisting of hydrogen, inert gases and mixtures thereof.
Claim 32
Dependent Claim
23 words
A method in accordance with claim 27 wherein said inert gases are selected from the group consisting of argon, helium and mixtures thereof.
Claim 33
Dependent Claim
22 words
A method in accordance with claim 25 wherein said microwave energy in Step 3 is generated by a 2.45 GHz microwave oven.
Claim 34
Dependent Claim
61 words
A method in accordance with claim 25 wherein in step 1 said article of metal or metalloid is enwrapped in a ceramic aggregate of granular material which further is contained in a refractory ceramic container, said granular material having an average particle size ranging from -4 to +100 mesh and being in intimate contact with said article of metal or metalloid.
Claim 35
Independent Claim
181 words
A method of providing a metal carbo-nitride coating on an article of metal or metalloid comprising the following steps: Step 1) providing an article of metal or metalloid having an intimately contacting enwrapment of a ceramic insulating material within a microwave oven; Step 2) introducing a carbon and nitrogen containing atmosphere within said microwave oven, said carbon containing atmosphere in said carbon and nitrogen containing atmosphere comprises gases selected from the group consisting of methene, acetylene, butane, and mixtures thereof, said nitrogen containing atmosphere in said carbon and nitrogen containing atmosphere comprises gases selected from the group consisting of nitrogen, ammonia and mixtures thereof. Step 3) heating said article of metal or metalloid in said atmosphere within said microwave oven to a temperature sufficient to react said methane and nitrogen in said atmosphere with said article of metal or metalloid by applying a microwave energy within said microwave oven; and Step 4) maintaining said article of metal or metalloid at said temperature for a period of time sufficient to form a coating of carbo-nitride on said article of metal or metalloid.
Claim 36
Independent Claim
181 words
A method of providing a metal carbo-nitride coating on an article of metal or metalloid comprising the following steps: Step 1) providing an article of metal or metalloid having an intimately contacting enwrapment of a ceramic insulating material within a microwave oven; Step 2) introducing a carbon and nitrogen containing atmosphere within said microwave oven, said carbon containing atmosphere in said carbon and nitrogen containing atmosphere comprises gases selected from the group consisting of methene, acetylene, butane, and mixtures thereof, said nitrogen containing atmosphere in said carbon and nitrogen containing atmosphere comprises gases selected from the group consisting of nitrogen, ammonia and mixtures thereof. Step 3) heating said article of metal or metalloid in said atmosphere within said microwave oven to a temperature sufficient to react said methane and nitrogen in said atmosphere with said article of metal or metalloid by applying a microwave energy within said microwave oven; and Step 4) maintaining said article of metal or metalloid at said temperature for a period of time sufficient to form a coating of carbo-nitride on said article of metal or metalloid.
Claim 37
Dependent Claim
44 words
A method in accordance with claim 31 wherein said article comprises a metal selected from the group consisting of titanium, tantalum, hafnium, zirconium, niobium and mixtures thereof or said article comprises a metalloid selected from the group consisting of silicon, boron, and mixtures thereof.
Claim 38
Dependent Claim
55 words
A method in accordance with claim 31 wherein said carbon and nitrogen containing atmosphere contains gases selected from the group consisting of ammonia, nitrogen and mixtures thereof and gases selected from the group consisting of methane, acetylene, butane and mixtures thereof and gases selected from the group consisting of hydrogen, inert gases and mixtures thereof.
Claim 39
Dependent Claim
23 words
A method in accordance with claim 33 wherein said inert gases are selected from the group consisting of argon, helium and mixtures thereof.
Claim 40
Dependent Claim
22 words
A method in accordance with claim 31 wherein said microwave energy in Step 3 is generated by a 2.45 GHz microwave oven.
Claim 41
Dependent Claim
61 words
A method in accordance with claim 31 wherein in step 1 said article of metal or metalloid is enwrapped in a ceramic aggregate of granular material which further is contained in a refractory ceramic container, said granular material having an average particle size range from -4 to +100 mesh and being in intimate contact with said article of metal or metalloid.
Claim 42
Independent Claim
242 words
A method of nitriding an article of silicon comprising the following steps: Step 1) pressing a powder mixture comprising 86.9 wt. % silicon, 9.8 wt. % yttria, and 3.3 wt. % alumina to form a pressed article, said silicon having a purity greater than 99.95%; Step 2) enwrapping said pressed article in a silicon nitride-2 wt. % yttria powder having a particle size of about 2 μm contained in a boron nitride crucible, said crucible being covered by an alumina fiber board and placed in a microwave oven; Step 3) introducing an argon containing atmosphere within said microwave oven, said argon containing atmosphere being comprised of argon gas; Step 4) heating said article of silicon to a temperature of about 1000° C. in said argon atmosphere by applying a microwave energy within said microwave oven; Step 5) introducing a nitrogen containing atmosphere within said microwave oven, said nitrogen containing atmosphere comprises gases selected from the group consisting of ammonia, nitrogen and mixtures thereof; Step 6) increasing said temperature of said article of silicon to about 1400° C. in said nitrogen atmosphere by applying a microwave energy within said microwave oven; and Step 7) maintaining said article of silicon at said temperature of Step 6 for a period of time sufficient to convert greater than 75% of said article of silicon to an article of silicon nitride, said article of silicon being heated by microwave energy for a period of about 24 hours.
Claim 43
Independent Claim
242 words
A method of nitriding an article of silicon comprising the following steps: Step 1) pressing a powder mixture comprising 86.9 wt. % silicon, 9.8 wt. % yttria, and 3.3 wt. % alumina to form a pressed article, said silicon having a purity greater than 99.95%; Step 2) enwrapping said pressed article in a silicon nitride-2 wt. % yttria powder having a particle size of about 2 μm contained in a boron nitride crucible, said crucible being covered by an alumina fiber board and placed in a microwave oven; Step 3) introducing an argon containing atmosphere within said microwave oven, said argon containing atmosphere being comprised of argon gas; Step 4) heating said article of silicon to a temperature of about 1000° C. in said argon atmosphere by applying a microwave energy within said microwave oven; Step 5) introducing a nitrogen containing atmosphere within said microwave oven, said nitrogen containing atmosphere comprises gases selected from the group consisting of ammonia, nitrogen and mixtures thereof; Step 6) increasing said temperature of said article of silicon to about 1400° C. in said nitrogen atmosphere by applying a microwave energy within said microwave oven; and Step 7) maintaining said article of silicon at said temperature of Step 6 for a period of time sufficient to convert greater than 75% of said article of silicon to an article of silicon nitride, said article of silicon being heated by microwave energy for a period of about 24 hours.
Claim 44
Independent Claim
145 words
A method of nitriding an article of metal or metalloid composite comprising the following steps: Step 1) providing an article of metal or metalloid composite having an intimately contacting enwrapment of a ceramic insulating material within a microwave oven; Step 2) introducing a nitrogen containing atmosphere within said microwave oven, said nitrogen containing atmosphere comprises gases selected from the group consisting of ammonia, nitrogen and mixtures thereof; Step 3) heating said article of metal or metalloid composite in said nitrogen containing atmosphere within said microwave oven to a temperature sufficient to react with said metal or metalloid composite with said nitrogen by applying a microwave energy within said microwave oven; and Step 4) maintaining said article of metal or metalloid composite at said temperature for a period of time sufficient to convert said article of metal or metalloid composite to an article of refractory nitride.
Claim 45
Independent Claim
145 words
A method of nitriding an article of metal or metalloid composite comprising the following steps: Step 1) providing an article of metal or metalloid composite having an intimately contacting enwrapment of a ceramic insulating material within a microwave oven; Step 2) introducing a nitrogen containing atmosphere within said microwave oven, said nitrogen containing atmosphere comprises gases selected from the group consisting of ammonia, nitrogen and mixtures thereof; Step 3) heating said article of metal or metalloid composite in said nitrogen containing atmosphere within said microwave oven to a temperature sufficient to react with said metal or metalloid composite with said nitrogen by applying a microwave energy within said microwave oven; and Step 4) maintaining said article of metal or metalloid composite at said temperature for a period of time sufficient to convert said article of metal or metalloid composite to an article of refractory nitride.
Claim 46
Dependent Claim
45 words
A method in accordance with claim 38 wherein said article comprises a metal selected from the group consisting of titanium, tantalum, hafnium, zirconium, niobium, aluminum, and mixtures thereof or said article comprises a metalloid selected from the group consisting of silicon, boron, and mixtures thereof.
Claim 47
Dependent Claim
22 words
A method in accordance with claim 38 wherein said microwave energy in Step 3 is generated by a 2.45 GHz microwave oven.
Claim 48
Dependent Claim
63 words
A method in accordance with claim 38 wherein in step 1 said article of metal or metalloid composite is enwrapped in a ceramic aggregate of granule materials which further is contained in a refractory ceramic container, said granular material having an average particle size ranging from -4 to +100 mesh and being in intimate contact with said article of metal or metalloid composite.
Claim 49
Dependent Claim
39 words
A method in accordance with claim 38 wherein said nitrogen containing atmosphere contains gases selected from the group consisting of ammonia, nitrogen and mixtures thereof and gases selected from the group consisting of hydrogen, inert gases and mixtures thereof.
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