Complex ceramic and metallic shaped by low pressure forming and sublimative drying
First Claim
1. A process for forming an article comprising:
- (a) providing a well-dispersed pourable slurry consisting essentially of at least about 35% by volume of inorganic sinterable particles, a non-aqueous vehicle having a volume change on freezing of not more than 10% by volume, and a dispersant selected from the group consisting of acrylic acid based polymeric polyelectrolytes, phosphate ethers, and combinations thereof;
(b) providing a closed mold of a desired geometry;
(c) injecting the slurry into the closed mold at a pressure of less than about 100 psi;
(d) decreasing the temperature of the mold to below the freezing point of the vehicle for a time sufficient to freeze the vehicle and to result in a solidified piece;
(e) drying the solidified piece by sublimation under conditions below the vapor pressure of the vehicle and below the melting point of the vehicle and without the formation of a continuous liquid phase effective to produce a green piece; and
(f) sintering the green piece to produce a densified article.
4 Assignments
0 Petitions
Accused Products
Abstract
A process for forming articles from inorganic sinterable particulates includes providing a well-dispersed, low pressure injectable slurry, freeze-forming the slurry into a desired geometry, and drying the piece so formed by a predominantly sublimative process, to produce a green article that can be conventionally sintered. The vehicle has a volume change on freezing of not more than ±10% by volume; to further control the volume change on freezing, an emulsion derived from different vehicles can be tailored. The slurries preferably have a solids content of at least about 35 v/o, a viscosity of preferably not more than about 1000 cP at 100 s-1, and are preferably injectable at not more than about 1000 psi, usually at less than 100 psi.
112 Citations
16 Claims
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1. A process for forming an article comprising:
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(a) providing a well-dispersed pourable slurry consisting essentially of at least about 35% by volume of inorganic sinterable particles, a non-aqueous vehicle having a volume change on freezing of not more than 10% by volume, and a dispersant selected from the group consisting of acrylic acid based polymeric polyelectrolytes, phosphate ethers, and combinations thereof; (b) providing a closed mold of a desired geometry; (c) injecting the slurry into the closed mold at a pressure of less than about 100 psi; (d) decreasing the temperature of the mold to below the freezing point of the vehicle for a time sufficient to freeze the vehicle and to result in a solidified piece; (e) drying the solidified piece by sublimation under conditions below the vapor pressure of the vehicle and below the melting point of the vehicle and without the formation of a continuous liquid phase effective to produce a green piece; and (f) sintering the green piece to produce a densified article. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A process for forming an article comprising:
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(a) providing a well-dispersed pourable slurry consisting essentially of at least about 35% by volume of inorganic sinterable particles, a non-aqueous vehicle having a volume change on freezing of not more than 10% by volume, and a dispersant selected from the group consisting of arcylic acid based polymeric polyelectrolytes, phosphate ethers, and combinations thereof; (b) providing a well-dispersed pourable slurry consisting essentially of at least about 10% by volume of inorganic sinterable particles, water, and a dispersant; (c) mixing the slurry of step (a) and the slurry of step (b) effective to form an emulsion slurry; (d) providing a closed mold of a desired geometry; (e) injecting the emulsion slurry into the closed mold at a pressure of less than about 100 psi; (f) decreasing the temperature of the mold to below the freezing point of the vehicle for a time sufficient to freeze the vehicle and to result in a solidified piece; (g) drying the solidified piece by sublimation under conditions below the vapor pressure of the vehicle and below the melting point of the vehicle and without the formation of a continuous liquid phase effective to produce a green piece; and (h) sintering the green piece to produce a densified article.
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Specification