Pressure slip casting process for making hollow-shaped ceramics
First Claim
1. A method of making a green ceramic article by pressure slip casting, comprising the steps of:
- a) providing a slip casting mold including porous mold part means having a molding-cavity-defining surface and porosity channels opening thereto having a given average cross-sectional channel dimension;
b) providing a slip composition comprising a liquid vehicle, a binder, solid phase particulate components with an average particle size distribution less than said porosity channel dimension and a flocculating agent to cause agglomeration of said solid component particles into floccules larger than said channel dimension;
c) flowing the slip via a molding cavity inlet into the molding cavity to fill the molding cavity with the slip composition;
d) hydrostatically pressurizing the slip composition in the molding cavity while withdrawing slip filtrate from the molding cavity via the mold porosity channels at a pressure and for a time sufficient to deposit to a desired thickness a layer of solids from slip on a molding cavity surface-deposit layer interface;
e) removing excess slip from the molding cavity via a molding cavity outlet to provide a surface on said deposit layer exposed to the interior of the molding cavity;
f) applying air under pressure to the exposed interior surface of said deposit layer while withdrawing slip filtrate via the mold porosity channels from the molding and cavity surface-deposit layer interface for a time and at sufficient air pressure differential to cause the air to effect a liquid vehicle drying action on said interface by flow of the air therealong and to rupture the liquid vehicle-solid particle bonds so that the liquid vehicle molecules may be forced by the use of the air under pressure from within the deposit layer to the molding cavity surface-deposit layer interface to cause liquid vehicle to be forced from within said deposit layer to said interface for withdrawal therefrom; and
g) removing the slip casted green ceramic article from the mold after sufficient liquid vehicle has been removed from the article to cause the same to be self-supporting.
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Accused Products
Abstract
A method of making a hollow-shaped green ceramic article by pressure slip casting in a slip casting mold having a porous mold part with porosity channels opening at the surface of the mold cavity. A slip composition is formed having solid phase components with an average particle size distribution less than the cross-sectional dimension of mold porosity channels, and also having a flocculating agent to cause agglomeration of the solid phase particles into floccules larger than the porosity channel dimension.
The molding cavity is filled with the slip composition, and the same is then hydrostatically pressurized while withdrawing slip filtrate from the mold cavity via the mold porosity channels for a time sufficient to deposit to a desired thickness a layer of solids. Excess slip is then removed from the molding cavity to provide an exposed interior surface on the deposit layer. Air under pressure is then applied to the exposed interior surface of the deposit layer, preferably while also withdrawing slip filtrate via the mold porosity channels from the mold cavity surface-deposit layer interface. The slip casted green ceramic hollow article is removed from the mold only after sufficient water has been removed in situ from within the material of the green ceramic article to enable the same to be self-supporting.
68 Citations
11 Claims
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1. A method of making a green ceramic article by pressure slip casting, comprising the steps of:
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a) providing a slip casting mold including porous mold part means having a molding-cavity-defining surface and porosity channels opening thereto having a given average cross-sectional channel dimension; b) providing a slip composition comprising a liquid vehicle, a binder, solid phase particulate components with an average particle size distribution less than said porosity channel dimension and a flocculating agent to cause agglomeration of said solid component particles into floccules larger than said channel dimension; c) flowing the slip via a molding cavity inlet into the molding cavity to fill the molding cavity with the slip composition; d) hydrostatically pressurizing the slip composition in the molding cavity while withdrawing slip filtrate from the molding cavity via the mold porosity channels at a pressure and for a time sufficient to deposit to a desired thickness a layer of solids from slip on a molding cavity surface-deposit layer interface; e) removing excess slip from the molding cavity via a molding cavity outlet to provide a surface on said deposit layer exposed to the interior of the molding cavity; f) applying air under pressure to the exposed interior surface of said deposit layer while withdrawing slip filtrate via the mold porosity channels from the molding and cavity surface-deposit layer interface for a time and at sufficient air pressure differential to cause the air to effect a liquid vehicle drying action on said interface by flow of the air therealong and to rupture the liquid vehicle-solid particle bonds so that the liquid vehicle molecules may be forced by the use of the air under pressure from within the deposit layer to the molding cavity surface-deposit layer interface to cause liquid vehicle to be forced from within said deposit layer to said interface for withdrawal therefrom; and g) removing the slip casted green ceramic article from the mold after sufficient liquid vehicle has been removed from the article to cause the same to be self-supporting. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification