US4264354A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of making spherical dental alloy powders
Assignee: Individual
•
Filing: 1979-07-31
•
Granted: 1981-04-28
•
Expires: 1999-07-31
Abstract
Abstract A dental alloy powder containing silver, tin and copper and, optionally, other alloying metals which has been rendered spherical by a heat treatment to melt at least a surface stratum of the particles of the alloy, followed by cooling.
Inventors
- 👤 Jeffery J. Cheetham
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 20:36
CPC Classifications
A; A61; A61K; A61K6/00; A61K6/80; A61K6/84; A61K6/847
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
147 words
A method of producing a spherical dental alloy powder containing silver, tin, copper and, optionally, one or more other alloying metals, which comprises the following steps: (1) forming irregular solid particles of said alloy having a particle size distribution in the range from about 0.5 microns to about 100 microns; (2) entraining irregular solid particles from step (1) in a stream of inert carrier gas at elevated pressure so as to separate the particles from one another; (3) injecting said stream of inert carrier gas containing said irregular, separated, solid particles into and through a heating zone so as to melt at least a surface stratum of the particles; (4) passing the heat treated particles from step (3) into a body of liquid so as to cool the particles by immersion in said body of liquid; and (5) retrieving said cooled particles from the body of liquid.
Claim 2
Independent Claim
147 words
A method of producing a spherical dental alloy powder containing silver, tin, copper and, optionally, one or more other alloying metals, which comprises the following steps: (1) forming irregular solid particles of said alloy having a particle size distribution in the range from about 0.5 microns to about 100 microns; (2) entraining irregular solid particles from step (1) in a stream of inert carrier gas at elevated pressure so as to separate the particles from one another; (3) injecting said stream of inert carrier gas containing said irregular, separated, solid particles into and through a heating zone so as to melt at least a surface stratum of the particles; (4) passing the heat treated particles from step (3) into a body of liquid so as to cool the particles by immersion in said body of liquid; and (5) retrieving said cooled particles from the body of liquid.
Claim 3
Dependent Claim
26 words
A method according to claim 1, wherein said stream of inert carrier gas is at a pressure in the range from about 40 to 100 p.s.i.
Claim 4
Dependent Claim
26 words
A method according to claim 2, wherein said stream of inert carrier gas is at a pressure in the range from about 45 to 55 p.s.i.
Claim 5
Dependent Claim
41 words
A method according to claim 1, wherein said heating zone is in the form of a flame produced by combustion of a gas at elevated pressure, said flame having a reducing cone and said particles being passed through said reducing cone.
Claim 6
Dependent Claim
22 words
A method according to claim 1, wherein step (3) is performed in a closed container containing an atmosphere of an inert gas.
Claim 7
Dependent Claim
12 words
A method according to claim 5, wherein the inert gas is nitrogen.
Claim 8
Dependent Claim
44 words
A method according to claim 1, wherein, subsequent to step (1) and prior to step (2), the irregular particles are subjected to size selection procedures to retain particles having a particle size distribution in the range from about 5 microns to about 40 microns.
Claim 9
Dependent Claim
16 words
A method according to claim 1, wherein said body of liquid in step (4) is water.
Claim 10
Dependent Claim
35 words
A method according to claim 1, wherein said alloy powder contains from about 35 to 85% silver, from about 7.5 to 40% tin, from about 5 to 40% copper and from 0 to 2% indium.
Claim 11
Dependent Claim
36 words
A method according to claim 9, wherein said alloy powder contains from about 40 to 75% silver, from about 10 to 30% tin, from about 10 to 30% copper and from about 0 to 2% indium.
Claim 12
Dependent Claim
37 words
A method according to claim 1, wherein said irregular particles of step (1) are obtained from an ingot of the alloy by comminution thereof to produce fine turnings and then subjecting the fine turnings to size reduction.
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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) | 1984-04-27 | 1984-10-27 | 1985-04-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-04-27 | 1988-10-27 | 1989-04-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-04-27 | 1992-10-27 | 1993-04-28 | $7700.00 | Window Closed / Lapsed |