Patent US4822692A successfully refreshed from Google Patents.
US4822692A
Expired / Lapsed
US
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Seamless porous metal article and method of making
Assignee: Pall Corp
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Filing: 1987-11-12
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Granted: 1989-04-18
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Expires: 2007-11-12
Abstract
Abstract A method for making seamless, porous metal articles comprising: (a) rotating a mold containing a stabilized suspension of a metal particulate at a rate and for a time such that the particulate is separated from the suspension and distributed on the interior wall of the mold, thereby forming a structure conforming to the interior wall of the mold, the rate of rotation being sufficiently high that at least about 100 Gs of centrifugal acceleration is achieved at the interior wall of the structure, (b) drying the formed structure to provide a structure having green or unsintered strength, and (c) sintering the dried structure to remove volatile material and fuse the individual particles of the particulate to each other to form the seamless, porous metal article. Metal articles in accordance with the invention have substantially uniform diameters, thicknesses and pore structures, have Bubble Point ratios of 1.5 or less, and find particular use as filters.
Inventors
- 👤 Paul C. Koehler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 23:10
CPC Classifications
B; B01; B01D; B01D39/00; B01D39/14; B01D39/20; B01D39/2027; B01D39/2031; B01D39/2034; B22; B22F; B22F3/00; B22F3/02; B22F3/06; B22F3/10; B22F3/11; B22F3/1103; B22F3/1109; B22F3/22; Y; Y10; Y10T; Y10T428/00; Y10T428/12; Y10T428/12014; Y10T428/12021; Y10T428/12028; Y10T428/12042; Y10T428/12153
Claims Analysis
Total Claims: 33
Claim 1
Independent Claim
143 words
A method of manufacturing a seamless, hollow, porous article comprising: (a) rotating a mold containing a stabilized suspension of a metal particulate at a rate and for a time such that said particulate is separated from said suspension and distributed on the interior wall of said mold, thereby forming a structure conforming to the interior wall of said mold and supernatant fluid, the rate of rotation being sufficiently high that at least about 100 Gs of acceleration is achieved at the interior wall of said structure; (b) removing said supernatant fluid and drying said structure to provide a dried structure having green or unsintered strength; (c) sintering the dried structure to remove volatile material and fuse the individual particles of said particulate to each other to form a seamless, hollow, porous article; and (d) removing the seamless, hollow, porous article from said mold.
Claim 2
Independent Claim
143 words
A method of manufacturing a seamless, hollow, porous article comprising: (a) rotating a mold containing a stabilized suspension of a metal particulate at a rate and for a time such that said particulate is separated from said suspension and distributed on the interior wall of said mold, thereby forming a structure conforming to the interior wall of said mold and supernatant fluid, the rate of rotation being sufficiently high that at least about 100 Gs of acceleration is achieved at the interior wall of said structure; (b) removing said supernatant fluid and drying said structure to provide a dried structure having green or unsintered strength; (c) sintering the dried structure to remove volatile material and fuse the individual particles of said particulate to each other to form a seamless, hollow, porous article; and (d) removing the seamless, hollow, porous article from said mold.
Claim 3
Dependent Claim
16 words
The method of claim 1 wherein said mold is substantially completely filled with said stabilized suspension.
Claim 4
Dependent Claim
30 words
The method of claim 2 wherein the rate of rotation is at such that at least about 110 Gs of acceleration is achieved at the interior wall of said structure.
Claim 5
Dependent Claim
29 words
The method of claim 3 wherein the weight ratio of said metal particulate in said stabilized suspension to the other components therein is from about 5:1 to about 1:1.
Claim 6
Dependent Claim
37 words
The method of claim 4 wherein said metal particulate is stainless steel, said mold is ceramic and said sintering is carried out at a temperature in the range of from about 1,600 to about 2,550 degrees F.
Claim 7
Dependent Claim
57 words
The method of claim 5 wherein said metal particulate is austenitic stainless steel, the weight ratio of said metal particulate in said stabilized suspension to the other components therein is from about 4.5:1 to about 3.5:1 and said sintering is carried out at a temperature in the range of from about 1,900 to about 2,525 degrees F.
Claim 8
Dependent Claim
201 words
The method of claim 6 wherein said stabilized suspension comprises (1) water, (2) a stabilizing/binding agent comprising a polyacrylic acid and (3) austenitic stainless steel particles having average particle sizes in the range of from about 25 to about 150 micrometers, the weight ratio of said metal particulate in said stabilized suspension to the other components therein is in the range of from about 3.5:1 to about 4.5:1, said mold has an inside diameter in the range of from about 1 to about 4 inches and an L/D of from about 1 to about 100, said stainless steel particles have a coefficient of thermal expansion at least one and one-half times as great as said mold, the rotation of said mold is carried out with said mold in a horizontal position, said drying is carried out with said mold in a horizontal position, said sintering is carried out with said mold in a vertical position and the formed seamless, hollow porous article has a wall thickness of from about 0.005 to about 0.25 of an inch, an F2 rating at beta equal 100 of from about 1 to about 100 micrometers and a Bubble Point ratio of about 1.5 or less.
Claim 9
Dependent Claim
44 words
The method of claim 1 wherein the rotation of said mold is carried out with said mold in a horizontal position, said drying step is carried out with said mold in a horizontal position and said sintering is carried out in a vertical position.
Claim 10
Dependent Claim
57 words
The method of claim 1 wherein steps (a) and (b) are repeated at least once with at least a second stabilized suspension of a second metal particulate having a different particle size distribution than that of the first stabilized suspension prior to carrying out step (c) thereby forming a seamless, hollow, porous article with a layered structure.
Claim 11
Dependent Claim
19 words
The method of claim 1 wherein one or more fitments is inserted into said mold prior to said sintering.
Claim 12
Independent Claim
213 words
A method for manufacturing a seamless, hollow, porous article having a graded pore structure comprising: (a) rotating a mold containing a stabilized suspension of a metal particulate having a distribution of particle sizes dispersed in a fluid medium, said mold having a coefficient of thermal expansion less than that of said metal particulate, at a first lower rate to first separate larger size particles from said suspension and distribute them over the interior wall of said mold; (b) rotating said mold at at least one higher rate of revolution to separate smaller size particles from said suspension and distribute them over the previously distributed larger particles, thereby forming a structure conforming to the interior wall of said mold and supernatant fluid, said mold being rotated at a rate such that at least about 100 Gs of acceleration is achieved at the interior wall of said structure; (c) removing said supernatant fluid and drying said structure to provide a dried structure having green or unsintered strength; (d) sintering the dried structure to remove volatile material and fuse the individual particles of said particulate to each other to form a seamless, hollow, porous article having a graded pore structure; and (e) removing the seamless, hollow, porous article having a graded pore structure from said mold.
Claim 13
Independent Claim
213 words
A method for manufacturing a seamless, hollow, porous article having a graded pore structure comprising: (a) rotating a mold containing a stabilized suspension of a metal particulate having a distribution of particle sizes dispersed in a fluid medium, said mold having a coefficient of thermal expansion less than that of said metal particulate, at a first lower rate to first separate larger size particles from said suspension and distribute them over the interior wall of said mold; (b) rotating said mold at at least one higher rate of revolution to separate smaller size particles from said suspension and distribute them over the previously distributed larger particles, thereby forming a structure conforming to the interior wall of said mold and supernatant fluid, said mold being rotated at a rate such that at least about 100 Gs of acceleration is achieved at the interior wall of said structure; (c) removing said supernatant fluid and drying said structure to provide a dried structure having green or unsintered strength; (d) sintering the dried structure to remove volatile material and fuse the individual particles of said particulate to each other to form a seamless, hollow, porous article having a graded pore structure; and (e) removing the seamless, hollow, porous article having a graded pore structure from said mold.
Claim 14
Dependent Claim
16 words
The method of claim 11 wherein said mold is substantially completely filled with said stabilized suspension.
Claim 15
Dependent Claim
30 words
The method of claim 12 wherein the rate of rotation is at such that at least about 110 Gs of acceleration is achieved at the interior wall of said structure.
Claim 16
Dependent Claim
29 words
The method of claim 13 wherein the weight ratio of said metal particulate in said stabilized suspension to the other components therein is from about 5:1 to about 1:1.
Claim 17
Dependent Claim
37 words
The method of claim 14 wherein said metal particulate is stainless steel, said mold is ceramic and said sintering is carried out at a temperature in the range of from about 1,600 to about 2,550 degrees F.
Claim 18
Dependent Claim
57 words
The method of claim 15 wherein said metal particulate is austenitic stainless steel, the weight ratio of said metal particulate in said stabilized suspension to the other components therein is from about 4.5:1 to about 3.5:1 and said sintering is carried out at a temperature in the range of from about 1,900 to about 2,525 degrees F.
Claim 19
Dependent Claim
201 words
The method of claim 16 wherein said stabilized suspension comprises (1) water, (2) a stabilizing/binding agent comprising a polyacrylic acid and (3) austenetic stainless steel particles having average particle sizes in the range of from about 25 to about 150 micrometers, the weight ratio of said metal particulate in said stabilized suspension to the other components therein is in the range of from about 3.5:1 to about 4.5:1, said mold has an inside diameter in the range of from about 1 to about 4 inches and an L/D of from about 1 to about 100, said stainless steel particles have a coefficient of thermal expansion at least one and one-half times as great as said mold, the rotation of said mold is carried out with said mold in a horizontal position, said drying is carried out with said mold in a horizontal position, said sintering is carried out with said mold in a vertical position and the formed seamless, hollow porous article has a wall thickness of from about 0.005 to about 0.25 of an inch, an F2 rating at beta equal 100 of from about 1 to about 100 micrometers and a Bubble Point ratio of about 1.5 or less.
Claim 20
Dependent Claim
44 words
The method of claim 11 wherein the rotation of said mold is carried out with said mold in a horizontal position, said drying step is carried out with said mold in a horizontal position and said sintering is carried out in a vertical position.
Claim 21
Dependent Claim
19 words
The method of claim 11 wherein one or more fitments is inserted into said mold prior to said sintering.
Claim 22
Dependent Claim
44 words
A seamless, hollow porous metal article of substantially uniform diameter, wall thickness and pore structure comprising metal particulate in which the individual particles of said particulate are bonded to each other and said article has a Bubble Point ratio of about 1.5 or less.
Claim 23
Dependent Claim
44 words
A seamless, hollow porous metal article of substantially uniform diameter, wall thickness and pore structure comprising metal particulate in which the individual particles of said particulate are bonded to each other and said article has a Bubble Point ratio of about 1.5 or less.
Claim 24
Dependent Claim
15 words
The porous metal article of claim 20 wherein said article has a graded pore structure.
Claim 25
Dependent Claim
13 words
The porous metal article of claim 21 wherein said particulate is stainless steel.
Claim 26
Dependent Claim
22 words
The porous metal article of claim 22 wherein said article has a wall thickness of from about 0.005 to about 1 inch.
Claim 27
Dependent Claim
26 words
The porous metal article of claim 23 wherein said article has an F2 rating at beta equals 100 of from about 1 to about 100 micrometers.
Claim 28
Dependent Claim
32 words
The porous metal article of claim 24 wherein said stainless steel is austenitic stainless steel and said article has a wall thickness of from about 0.005 to about 0.25 of an inch.
Claim 29
Dependent Claim
22 words
The porous metal article of claim 25 wherein said article comprises a finer pored outer layer and a coarser pored inner layer.
Claim 30
Dependent Claim
25 words
The porous metal article of claim 26 wherein said outer layer is about 0.015 inches thick and said inner layer is about 0.040 inches thick.
Claim 31
Dependent Claim
46 words
The porous metal article of claim 27 wherein said article has a nominal 4 inch outer diameter, said outer layer comprises metal particulate having a nominal particle size of -50, +100, and said inner layer comprises metal particulate having a nominal particle size of -200, +325.
Claim 32
Dependent Claim
19 words
The porous metal article of claim 27 wherein said article has one or more fittings sinter-bonded to said article.
Claim 33
Dependent Claim
26 words
The porous metal article of claim 24 wherein said article has an F2 rating at beta equals 100 of from about 5 to about 40 micrometers.
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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) | 1992-04-17 | 1992-10-17 | 1993-04-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-04-17 | 1996-10-17 | 1997-04-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-04-17 | 2000-10-17 | 2001-04-18 | $7700.00 | Window Closed / Lapsed |