US4763423A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for drying fine metal powders
Assignee: Osram Sylvania Inc
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Filing: 1987-07-06
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Granted: 1988-08-16
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Expires: 2007-07-06
Abstract
Abstract A method is disclosed for removing essentially all of the water from fine metal powders. The method involves contacting the powder particles which have water on at least some of the particle surfaces with a solution of a fluorocarbon solvent and a hydrophobic surfactant, with the amount of the surfactant being sufficient to form at least a monolayer adsorbed onto the particle surfaces, and with the amount of the solution being sufficient to at least fill the void volume of the particles, to displace essentially all of the water which is in contact with the water. The displaced water and the major portion of the solution which is not in direct contact with the powder is physically removed from the resulting treated powder. The powder is then dried at a temperature above the vaporization temperature of the fluorocarbon at the operating pressure of the drying equipment to remove the remainder of the fluorocarbon from the treated powder without removing significant amounts of surfactant therefrom. Alternately, if it is desired that the remainder of the surfactant be removed, the treated powder is dried at a temperature above the vaporization temperature of the surfactant.
Inventors
- 👤 Preston B. Kemp, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 04:27
CPC Classifications
F; F26; F26B; F26B5/00; F26B5/005; B; B22; B22F; B22F1/00; B22F1/14
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
174 words
A method for drying fine metal powders, said method comprising: (a) contacting said metal powder, having water on at least some of the surfaces of its particles with a solution of a fluorocarbon solvent and a hydrophobic surfactant, with the amounts of said surfactant in said solution being sufficient to form at least a monolayer adsorbed onto said surfaces, and with the amount of said solution being sufficient to at least fill the void volume of said particles to displace essentially all of the water which is in contact with said powder; (b) physically removing essentially all of the displaced water and the major portion of the solution which is not in direct contact with said particles, from the resulting surfactant-treated powder; and (c) drying said surfactant-treated powder at a temperature above the vaporization temperature of said fluorocarbon at the operating pressure of the drying equipment to remove the remainder of said fluorocarbon from said metal powder without removing significant amounts of any surfactant remaining on said powder, to produce the dried metal powder.
Claim 2
Independent Claim
174 words
A method for drying fine metal powders, said method comprising: (a) contacting said metal powder, having water on at least some of the surfaces of its particles with a solution of a fluorocarbon solvent and a hydrophobic surfactant, with the amounts of said surfactant in said solution being sufficient to form at least a monolayer adsorbed onto said surfaces, and with the amount of said solution being sufficient to at least fill the void volume of said particles to displace essentially all of the water which is in contact with said powder; (b) physically removing essentially all of the displaced water and the major portion of the solution which is not in direct contact with said particles, from the resulting surfactant-treated powder; and (c) drying said surfactant-treated powder at a temperature above the vaporization temperature of said fluorocarbon at the operating pressure of the drying equipment to remove the remainder of said fluorocarbon from said metal powder without removing significant amounts of any surfactant remaining on said powder, to produce the dried metal powder.
Claim 3
Dependent Claim
71 words
A method of claim 1 comprising the additional steps after step (b) and before step (c): (a) contacting said surfactant-treated powder with a fluorocarbon solvent to solubilize any surfactant which is in excess of that required to form a monolayer on the surfaces of said particles and to solubilize the major portion of the surfactant which is present as said monolayer; and (b) removing the resulting surfactant-fluorocarbon solution from said particles.
Claim 4
Dependent Claim
10 words
A method of claim 1 wherein said fluorocarbon is trichlorotrifluoroethane.
Claim 5
Dependent Claim
14 words
A method of claim 1 wherein said surfactant is an oil soluble cationic type.
Claim 6
Dependent Claim
12 words
A method of claim 4 wherein said surfactant is a fatty imidazoline.
Claim 7
Dependent Claim
23 words
A method of claim 1 wherein said fine metal powder has an average particle size of less than about 100 micrometers in diameter.
Claim 8
Dependent Claim
17 words
A method of claim 6 wherein said particle size is less than about 30 micrometers in diameter.
Claim 9
Dependent Claim
17 words
A method of claim 7 wherein said particle size is less than about 10 micrometers in diameter.
Claim 10
Independent Claim
163 words
A method for drying fine metal powders, said method comprising: (a) contacting said metal powder, having water on at least some of the surfaces of its particles with a solution of a fluorocarbon solvent and a hydrophobic surfactant, with the amounts of said surfactant in said solution being sufficient to form at least a monolayer adsorbed onto said surfaces, and with the amount of said solution being sufficient to at least fill the void volume of said particles to displace essentially all of the water which is in contact with said powder; (b) physically removing essentially all of the displaced water and the major portion of the solution which is not in direct contact with said particles, from the resulting surfactant-treated powder; and (c) drying said surfactant-treated powder at a temperature above the vaporization temperature of said surfactant at the operating pressure of the drying equipment to remove the remainder of said surfactant from said metal powder to produce the dried metal powder.
Claim 11
Independent Claim
163 words
A method for drying fine metal powders, said method comprising: (a) contacting said metal powder, having water on at least some of the surfaces of its particles with a solution of a fluorocarbon solvent and a hydrophobic surfactant, with the amounts of said surfactant in said solution being sufficient to form at least a monolayer adsorbed onto said surfaces, and with the amount of said solution being sufficient to at least fill the void volume of said particles to displace essentially all of the water which is in contact with said powder; (b) physically removing essentially all of the displaced water and the major portion of the solution which is not in direct contact with said particles, from the resulting surfactant-treated powder; and (c) drying said surfactant-treated powder at a temperature above the vaporization temperature of said surfactant at the operating pressure of the drying equipment to remove the remainder of said surfactant from said metal powder to produce the dried metal powder.
Claim 12
Dependent Claim
71 words
A method of claim 9 comprising the additional steps after step (b) and before step (c): (a) contacting said surfactant-treated powder with a fluorocarbon solvent to solubilize any surfactant which is in excess of that required to form a monolayer on the surfaces of said particles and to solubilize the major portion of the surfactant which is present as said monolayer; and (b) removing the resulting surfactant-fluorocarbon solution from said particles.
Claim 13
Dependent Claim
23 words
A method of claim 9 wherein said fine metal powder has an average particle size of less than about 100 micrometers in diameter.
Claim 14
Dependent Claim
17 words
A method of claim 11 wherein said particle size is less than about 30 micrometers in diameter.
Claim 15
Dependent Claim
17 words
A method of claim 12 wherein said particle size is less than about 10 micrometers in diameter.
Claim 16
Dependent Claim
10 words
A method of claim 9 wherein said fluorocarbon is trichlorotrifluoroethane.
Claim 17
Dependent Claim
14 words
A method of claim 14 wherein said surfactant is an oil soluble cationic type.
Claim 18
Dependent Claim
12 words
A method of claim 15 wherein said surfactant is a fatty imidazoline.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-08-16 | 1992-02-15 | 1992-08-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-08-16 | 1996-02-15 | 1996-08-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-08-16 | 2000-02-15 | 2000-08-16 | $7700.00 | Window Closed / Lapsed |