US5047181A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Forming of complex high performance ceramic and metallic shapes
Assignee: Metals Process Systems
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Filing: 1991-02-25
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Granted: 1991-09-10
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Expires: 2011-02-25
Abstract
Abstract Dense, flaw free, complex, 3-dimensional, metal or refractory shapes are formed by preparing a low viscosity, pourable aqueous-based suspension. The aqueous suspension preferably contains ceramic or metal particulates, water, and a compatible mixture of additives for performing dispersant, cryoprotectant, and strength enhancing functions. The low viscosity slip is cast or injection molded at low pressure into a complex mold, frozen, demolded, and freeze dried without the formation of a continuous liquid phase. The green part is subsequently sintered by conventional techniques to achieve a dense part.
Inventors
- 👤 Mark A. Occhionero
- 👤 Bruce E. Novich
- 👤 Cathryn A. Sundback
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 20:54
CPC Classifications
B; B22; B22F; B22F3/00; B22F3/22; B22F3/225; B22F3/222; C; C04; C04B; C04B35/00; C04B35/622; C04B35/626; C04B35/63; C04B35/632; B22F2998/00
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
131 words
A process for producing a sintered ceramic or metallic article, comprising: a. providing a stable, pourable suspension consisting essentially of at least about 35 vol % solid ceramic particles or metallic particles or combinations thereof and a vehicle composed of a dispersant selected from the group consisting of acrylate-based polymeric polyelectrolytes and polyethylene imines, at least one cryoprotectant, and the remainder water; b. shaping the suspension in a closed mold at a pressure of less than about 200 psi; c. chilling the mold temperature to less than the freezing point of the vehicle; d. solidifying the shaped suspension by rapidly freezing the shaped suspension; e. freeze drying the solidified shape below the freezing point of the vehicle without the formation of a continuous liquid phase; and f. firing the dried shape.
Claim 2
Dependent Claim
131 words
A process for producing a sintered ceramic or metallic article, comprising: a. providing a stable, pourable suspension consisting essentially of at least about 35 vol % solid ceramic particles or metallic particles or combinations thereof and a vehicle composed of a dispersant selected from the group consisting of acrylate-based polymeric polyelectrolytes and polyethylene imines, at least one cryoprotectant, and the remainder water; b. shaping the suspension in a closed mold at a pressure of less than about 200 psi; c. chilling the mold temperature to less than the freezing point of the vehicle; d. solidifying the shaped suspension by rapidly freezing the shaped suspension; e. freeze drying the solidified shape below the freezing point of the vehicle without the formation of a continuous liquid phase; and f. firing the dried shape.
Claim 3
Dependent Claim
15 words
The process as defined by claim 1, wherein the suspension further comprises a drying agent.
Claim 4
Dependent Claim
15 words
The process as defined by claim 1, wherein the suspension further comprises a viscosity modifier.
Claim 5
Dependent Claim
42 words
The process as defined by claim 1, wherein the cryoprotectant is selected from the group consisting of dimethylsulfoxide, methanol, ethanol, isopropanol, ethylene glycol, polyethylene glycol, glycerin, 1,2-propanediol, urea, sugar, aminoacetic acid, oxalic acid, glycerol, polyvinyl alcohol, methylcellulose, ethylcellulose, polyvinylpyrrolidone, and mixtures thereof.
Claim 6
Dependent Claim
18 words
The process as defined by claim 4, wherein the cryoprotectant includes a mixture of at least two cryoprotectants.
Claim 7
Dependent Claim
18 words
The process as defined by claim 1, wherein the step of shaping is by low pressure injection molding.
Claim 8
Dependent Claim
41 words
The process as defined by claim 1, wherein the particles are a ceramic selected from among the oxides, carbides, nitrides, silicides, borides, silicates, titanates, zirconates, and mixtures thereof, of aluminum, beryllium, boron, lanthanum, lead, silicon, tungsten, titanium, zirconium, and mixtures thereof.
Claim 9
Dependent Claim
28 words
The process as defined by claim 7, where the ceramic is alumina, zirconia, cordierite, silica, silicon nitride, sialon, zirconia toughened alumina, SiC whisker reinforced alumina, or mixtures thereof.
Claim 10
Dependent Claim
31 words
The process as defined by claim 1, wherein the particles are composed of a metal selected from among aluminum, nickel, iron, titanium, copper, tungsten, molybdenum, beryllium, and mixtures and alloys thereof.
Claim 11
Dependent Claim
13 words
The process as defined by claim 1, wherein step (b) precedes step (c).
Claim 12
Dependent Claim
13 words
The process as defined by claim 1, wherein step (c) precedes step (b).
Claim 13
Dependent Claim
19 words
The process as defined by claim 1, wherein the volume fraction of solids is at least 50% by volume.
Claim 14
Dependent Claim
19 words
The process as defined by claim 12, wherein the volume fraction of solids is at least 55% by volume.
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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) | 1994-09-09 | 1995-03-11 | 1995-09-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-09-09 | 1999-03-11 | 1999-09-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-09-09 | 2003-03-11 | 2003-09-10 | $7700.00 | Window Closed / Lapsed |