US4994107A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Aerosol reactor production of uniform submicron powders
Assignee: California Institute of Technology
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Filing: 1988-09-08
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Granted: 1991-02-19
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Expires: 2008-09-08
Abstract
Abstract A method of producing submicron nonagglomerated particles in a single stage reactor includes introducing a reactant or mixture of reactants at one end while varying the temperature along the reactor to initiate reactions at a low rate. As homogeneously small numbers of seed particles generated in the initial section of the reactor progress through the reactor, the reaction is gradually accelerated through programmed increases in temperature along the length of the reactor to promote particle growth by chemical vapor deposition while minimizing agglomerate formation by maintaining a sufficiently low number concentration of particles in the reactor such that coagulation is inhibited within the residence time of particles in the reactor. The maximum temperature and minimum residence time is defined by a combination of temperature and residence time that is necessary to bring the reaction to completion. In one embodiment, electronic grade silane and high purity nitrogen are introduced into the reactor and temperatures of approximately 770° K. to 1550° K. are employed. In another embodiment silane and ammonia are employed at temperatures from 750° K. to 1800° K.
Inventors
- 👤 Richard C. Flagan
- 👤 Jin J. Wu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 04:30
CPC Classifications
C; C01; C01B; C01B32/00; C01B32/90; B; B22; B22F; B22F9/00; B22F9/02; B22F9/12; B82; B82Y; B82Y30/00; C01B21/00; C01B21/06; C01B21/068; C01B33/00; C01B33/02; C01B33/021; C01B33/027; C01B33/029; C01P; C01P2004/00; C01P2004/01; C01P2004/03; C01P2004/51; C01P2004/60; C01P2004/61; C01P2004/62; C01P2004/64
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
208 words
A method of producing submicron nonagglomerated particles of material in a single-stage flow reactor from a reactant or mixture of reactants containing a material out of which said particles are to be produced, said single-stage flow reactor defining a flow path, comprising the steps of: introducing a reactant or mixture of reactants at one end of said single-stage flow reactor; increasing the temperature along an initial section of said flow path of said single-stage flow reactor to initiate reaction at a rate to homogeneously generate seed particles in an initial section of said single-stage flow reactor; accelerating the reaction by increasing the temperature along said flow path of said single-stage flow reactor without mixing additional reactants with said seed particles in said flow path, thereby promoting growth of particles by chemical vapor deposition while minimizing agglomerate formation; and maintaining a concentration of particles in said single-stage flow reactor such that coagulation is inhibited within the residence time of said particles in said single-stage flow reactor, wherein the maximum temperature along the flow path of said single-stage flow reactor and a flow rate through said single-stage flow reactor along said flow path are controlled to bring the reaction to completion in the residence time of said submicron nonagglomerated particles.
Claim 2
Independent Claim
208 words
A method of producing submicron nonagglomerated particles of material in a single-stage flow reactor from a reactant or mixture of reactants containing a material out of which said particles are to be produced, said single-stage flow reactor defining a flow path, comprising the steps of: introducing a reactant or mixture of reactants at one end of said single-stage flow reactor; increasing the temperature along an initial section of said flow path of said single-stage flow reactor to initiate reaction at a rate to homogeneously generate seed particles in an initial section of said single-stage flow reactor; accelerating the reaction by increasing the temperature along said flow path of said single-stage flow reactor without mixing additional reactants with said seed particles in said flow path, thereby promoting growth of particles by chemical vapor deposition while minimizing agglomerate formation; and maintaining a concentration of particles in said single-stage flow reactor such that coagulation is inhibited within the residence time of said particles in said single-stage flow reactor, wherein the maximum temperature along the flow path of said single-stage flow reactor and a flow rate through said single-stage flow reactor along said flow path are controlled to bring the reaction to completion in the residence time of said submicron nonagglomerated particles.
Claim 3
Dependent Claim
36 words
The method of claim 1 in which the step of accelerating the reaction by increasing temperature along said flow path is carried out in a single zone of said single-stage flow reactor following said initial section.
Claim 4
Dependent Claim
37 words
The method of claim 1 in which the step of accelerating the reaction by increasing temperature along said flow path is carried out over a plurality of zones of said single-stage flow reactor following said initial section.
Claim 5
Dependent Claim
36 words
The method of claim 1 in which the concentration of seed particles generated in said initial section of said single-stage flow reactor is controlled to inhibit agglomeration in order to minimize variation in ultimate particle size.
Claim 6
Dependent Claim
26 words
The method of claim 1 in which the temperature and flow rate are controlled to generate end particles in the range of 0.05 to 0.5 microns.
Claim 7
Dependent Claim
16 words
The method of claim 5 in which the reactant is silane and a diluent is nitrogen.
Claim 8
Dependent Claim
29 words
The method of claim 6 in which the variation of the temperature along said flow path of said single-stage flow reactor ranges from approximately 770° K. to 1550° K.
Claim 9
Dependent Claim
13 words
The method of claim 5 in which the reactants are silane and ammonia.
Claim 10
Dependent Claim
26 words
The method of claim 1 in which the reactant is a halogenated metal and a reducing agent from Group I of the Periodic Table is employed.
Claim 11
Dependent Claim
26 words
The method of claim 1 in which the reactants are a halogenated metal and ammonia and a reducing agent from Group I of the Periodic Table.
Claim 12
Dependent Claim
27 words
The method of claim 1 in which the reactants are a halogenated metal and a hydrocarbon and a reducing agent from Group I of the Periodic Table.
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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) | 1994-02-18 | 1994-08-20 | 1995-02-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-02-18 | 1998-08-20 | 1999-02-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-02-18 | 2002-08-20 | 2003-02-19 | $7700.00 | Window Closed / Lapsed |