US5571848A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for producing a microcellular foam
Assignee: Massachusetts Institute of Technology
•
Filing: 1995-01-20
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Granted: 1996-11-05
•
Expires: 2015-01-20
Abstract
Abstract The invention provides a method for producing a microcellular foam of a curable material by replicating a dissolvable particle preform and leaching away the dissolvable particle preform to yield the microcellular foam. The foam can be a preceramic polymer microcellular foam which can be pyrolyzed to form a ceramic microcellular foam. A method for making a composite including steps of producing a ceramic microcellular foam which is subsequently infiltrated to form the composite is also provided as are microcellular foams, ceramic microcellular foams and composites prepared according to the method of the invention.
Inventors
- 👤 Andreas Mortensen
- 👤 Thomas J. Fitzgerald
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 15:51
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/26; B; B29; B29C; B29C67/00; B29C67/20; B29C67/202; C04; C04B; C04B38/00; C04B38/04; C08J2383/00
Claims Analysis
Total Claims: 35
Claim 1
Independent Claim
98 words
A method for producing a microcellular foam of a curable material comprising: (1) providing dissolvable particles; (2) packing said dissolvable particles to form a preform; (3) infiltrating said preform with a liquid curable material to form an infiltrated preform; (4) cooling said infiltrated preform so that said liquid curable material hardens to form a hardened curable material infiltrated preform; (5) leaching said hardened curable material infiltrated preform so that said dissolvable particles dissolve to form a hardened curable material microcellular foam characterized by pores having dimensions in the range of from about 1 μm to about 1 mm.
Claim 2
Independent Claim
98 words
A method for producing a microcellular foam of a curable material comprising: (1) providing dissolvable particles; (2) packing said dissolvable particles to form a preform; (3) infiltrating said preform with a liquid curable material to form an infiltrated preform; (4) cooling said infiltrated preform so that said liquid curable material hardens to form a hardened curable material infiltrated preform; (5) leaching said hardened curable material infiltrated preform so that said dissolvable particles dissolve to form a hardened curable material microcellular foam characterized by pores having dimensions in the range of from about 1 μm to about 1 mm.
Claim 3
Dependent Claim
69 words
The method of claim 1 wherein in step (3) said liquid curable material is a preceramic polymer and further comprising steps of: (6) curing said hardened curable material microcellular foam so that said preceramic polymer cures to form a cured preceramic polymer microcellular foam; and (7) pyrolyzing said cured preceramic polymer microcellular foam so that said cured preceramic polymer microcellular foam is pyrolyzed to form a ceramic microcellular foam.
Claim 4
Dependent Claim
35 words
The method of claim 1 wherein said dissolvable particles are substantially spherical particles and are further characterized by a particle diameter size distribution in the range of from about 0.1 μm to about 1 cm.
Claim 5
Dependent Claim
16 words
The method of claim 1 wherein said dissolvable particles are dissolvable in an aqueous leaching agent.
Claim 6
Dependent Claim
22 words
The method of claim 4 wherein said dissolvable particles are selected from the group consisting of sodium chloride and potassium chloride particles.
Claim 7
Dependent Claim
30 words
The method of claim 1 wherein said step (2) of packing is carried out so that said dissolvable particles are homogeneously distributed within said preform to create open pore space.
Claim 8
Dependent Claim
19 words
The method of claim 6 further including steps of pressing and sintering said dissolvable particles to form said preform.
Claim 9
Dependent Claim
41 words
The method of claim 1 wherein said preform contains a gas and step (2) of infiltrating further includes evacuating said gas before applying pressure in the range of from about 1 atm to about 100 atm to form said infiltrated preform.
Claim 10
Dependent Claim
29 words
The method of claim 2 wherein said step (2) of infiltrating is carried out at a temperature and in an atmosphere selected so that said preceramic polymer remains liquid.
Claim 11
Dependent Claim
43 words
The method of claim 2 wherein said preceramic polymer pyrolyzes in step (7) to yield a ceramic characterized by a ceramic composition based on an element selected from the group consisting of silicon, nitrogen, carbon, oxygen, aluminum, titanium and boron and mixtures thereof.
Claim 12
Dependent Claim
44 words
The method of claim 10 wherein said preceramic polymer is selected from the group consisting of polycarbosilane, polytitanocarbosilane, polysilazane, polydisilazane, [B 10 H 12 ·diamine] x -based polymers and [Ti(NR) 2 ] x -based polymers wherein R is a carbon-containing group and mixtures thereof.
Claim 13
Dependent Claim
33 words
The method of claim 1 wherein said step (4) of cooling is carried out at a cooling rate and in an atmosphere selected to avoid internal stresses and cracking in said infiltrated preform.
Claim 14
Dependent Claim
38 words
The method of claim 1 further comprising a step of applying pressure during said step (4) of cooling so that flow of said liquid curable material compensates volume changes which occur upon hardening of said liquid curable material.
Claim 15
Dependent Claim
21 words
The method of claim 13 wherein said pressure is in the range of from about 1 atm to about 100 atm.
Claim 16
Dependent Claim
39 words
The method of claim 1 wherein said step (5) of leaching said hardened curable material infiltrated preform further comprises a step of immersing said hardened curable material infiltrated preform in a leaching agent so that said dissolvable particles dissolve.
Claim 17
Dependent Claim
34 words
The method of claim 2 wherein said step (6) of curing said hardened curable material microcellular foam is carried out so that said preceramic polymer does not melt during said step (7) of pyrolyzing.
Claim 18
Dependent Claim
29 words
The method of claim 2 wherein said step (6) of curing said hardened curable material microcellular foam further comprises a step of chemically reacting said preceramic polymer with oxygen.
Claim 19
Dependent Claim
49 words
The method of claim 17 wherein said hardened curable material microcellular foam is further characterized by an uncured preceramic polymer microcellular foam dimension and said uncured preceramic polymer foam dimension and heating rate are selected to avoid deterioration of said hardened curable material microcellular foam during said curing step.
Claim 20
Dependent Claim
49 words
The method of claim 2 wherein said step (6) of curing said hardened curable material microcellular foam further comprises a step of irradiating said preceramic polymer with an energy source selected from the group consisting of an electron beam, ultraviolet radiation, gamma radiation and a plasma and combinations thereof.
Claim 21
Dependent Claim
30 words
The method of claim 2 wherein said step (6) of curing said hardened curable material microcellular foam further comprises a step of heating said preceramic polymer in an inert atmosphere.
Claim 22
Dependent Claim
55 words
The method of claim 2 wherein said step (6) of curing is further characterized by a curing rate and a heat removal rate from said hardened curable material microcellular foam and wherein said curing rate and said heat removal rate are independently controlled to avoid melting or cracking of said hardened curable material microcellular foam.
Claim 23
Dependent Claim
37 words
The method of claim 2 wherein said step (7) of pyrolyzing is carried out at a pyrolysis temperature and in an atmosphere selected so that said ceramic microcellular foam is strong and remains stable at elevated temperatures.
Claim 24
Independent Claim
207 words
A method for producing a composite comprising: (1) providing dissolvable particles; (2) packing said dissolvable particles to form a preform; (3) infiltrating said preform with a liquid curable material to form an infiltrated preform; (4) cooling said infiltrated preform so that said liquid curable material hardens to form a hardened curable material infiltrated preform; (5) leaching said hardened curable material infiltrated preform so that said dissolvable particles dissolve to form a hardened curable material microcellular foam characterized by pores having dimensions in the range of from about 1 μm to about 1 mm; (6) curing said hardened curable material microcellular foam so that said preceramic polymer cures to form a cured preceramic polymer microcellular foam characterized by pores having dimensions in the range of from about 1 μm to about 1 mm; (7) pyrolyzing said cured preceramic polymer microcellular foam so that said cured preceramic polymer microcellular foam is pyrolyzed to form a ceramic microcellular foam characterized by pores having dimensions in the range of from about 1 μm to about 1 mm; (8) infiltrating said ceramic microcellular foam with a liquid infiltrant to form an infiltrated ceramic microcellular foam; and (9) cooling said infiltrated ceramic microcellular foam to solidify said liquid infiltrant and form a composite.
Claim 25
Independent Claim
207 words
A method for producing a composite comprising: (1) providing dissolvable particles; (2) packing said dissolvable particles to form a preform; (3) infiltrating said preform with a liquid curable material to form an infiltrated preform; (4) cooling said infiltrated preform so that said liquid curable material hardens to form a hardened curable material infiltrated preform; (5) leaching said hardened curable material infiltrated preform so that said dissolvable particles dissolve to form a hardened curable material microcellular foam characterized by pores having dimensions in the range of from about 1 μm to about 1 mm; (6) curing said hardened curable material microcellular foam so that said preceramic polymer cures to form a cured preceramic polymer microcellular foam characterized by pores having dimensions in the range of from about 1 μm to about 1 mm; (7) pyrolyzing said cured preceramic polymer microcellular foam so that said cured preceramic polymer microcellular foam is pyrolyzed to form a ceramic microcellular foam characterized by pores having dimensions in the range of from about 1 μm to about 1 mm; (8) infiltrating said ceramic microcellular foam with a liquid infiltrant to form an infiltrated ceramic microcellular foam; and (9) cooling said infiltrated ceramic microcellular foam to solidify said liquid infiltrant and form a composite.
Claim 26
Dependent Claim
32 words
The method of claim 23 wherein said liquid infiltrant is a liquid metal selected from the group consisting of aluminum, magnesium, lead, tin, copper, iron, nickel, titanium and silicon and mixtures thereof.
Claim 27
Dependent Claim
33 words
The method of claim 23 wherein said liquid infiltrant is a liquid alloy selected from the group consisting of aluminum, magnesium, lead, tin, copper, iron, nickel, titanium and silicon-based alloys and mixtures thereof.
Claim 28
Dependent Claim
31 words
The method of claim 23 wherein said liquid infiltrant is a liquid intermetallic compound selected from the group consisting of aluminum, titanium, nickel, niobium and iron-based intermetallic compounds and mixtures thereof.
Claim 29
Dependent Claim
70 words
The method of claim 23 wherein said liquid infiltrant is a liquid preceramic polymer selected from the group consisting of polycarbosilane, polytitanocarbosilane, polysilazane, polydisilazane, [B 10 H 12 ·diamine] x -based polymers and [Ti(NR) 2 ] x -based polymers wherein R is a carbon-containing group and mixtures thereof and further comprising a step of pyrolyzing said composite so that said preceramic polymer is pyrolyzed to form a ceramic matrix composite.
Claim 30
Dependent Claim
11 words
A microcellular foam prepared according to the method of claim 1.
Claim 31
Dependent Claim
12 words
A ceramic microcellular foam prepared according to the method of claim 2.
Claim 32
Dependent Claim
10 words
A composite prepared according to the method of claim 23.
Claim 33
Dependent Claim
10 words
A composite prepared according to the method of claim 24.
Claim 34
Dependent Claim
35 words
The method of claim 1 wherein said dissolvable particles are substantially spherical particles and are further characterized by a particle diameter size distribution in the range of from about 1 μm to about 1 mm.
Claim 35
Dependent Claim
35 words
The method of claim 1 wherein said dissolvable particles are substantially spherical particles and are further characterized by a particle diameter size distribution in the range of from about 1 μm to about 100 μm.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1999-11-05 | 2000-05-06 | 2000-11-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-11-05 | 2004-05-06 | 2004-11-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-11-05 | 2008-05-06 | 2008-11-05 | $7700.00 | Window Closed / Lapsed |