Aqueous gelcasting method for ceramic products

Patent metadata

Field	Value
Publication number	US-2020391407-A1
Application number	US-201816651285-A
Country	US
Kind code	A1
Filing date	Sep 25, 2018
Priority date	Sep 26, 2017
Publication date	Dec 17, 2020
Grant date	—

Abstract

The present disclosure relates to the manufacture of ceramic products by aqueous gelcasting. Exemplary ceramic products include sanitary ware, such as toilets and sinks. The process includes a slurrying step, a mixing step, a molding step involving aqueous gelcasting, a drying step, a glazing step, and a firing step.

First claim

1 . A method of producing a ceramic product comprising:
introducing a mixture comprising a liquid portion into a mold having a vent; freezing the liquid portion of the mixture in a controlled direction toward the vent of the mold to form a solid ceramic article; and ejecting the solid ceramic article from the mold.

2 . The method of claim 1 , wherein the vent is located in a second surface of the mold, and wherein the freezing step comprises directing a cooling agent toward a first surface of the mold opposite the second surface of the mold such that the controlled direction of the freezing step moves from the first surface toward the second surface of the mold.

3 . The method of claim 1 , wherein the freezing step comprises directing a cryogenic cooling agent across the mold.

4 . The method of claim 3 , wherein the cryogenic cooling agent is at least one of dry ice and liquid nitrogen.

5 . The method of claim 1 , wherein the mold is metallic.

6 . The method of claim 1 , wherein the freezing step occurs in 30 minutes or less.

7 . The method of claim 1 , wherein the mixture includes colloidal silica, and wherein the freezing step comprises destabilizing the colloidal silica in the mixture to solidify the mixture.

8 . The method of claim 1 , wherein the introducing step comprises injecting the mixture into the mold under a pressure of 2 psi or less.

9 . The method of claim 1 , further comprising thermally drying the solid ceramic article in a low humidity environment.

10 . The method of claim 1 , wherein the solid ceramic article has a temperature gradient after the freezing step, the method further comprising:
normalizing a temperature of the solid ceramic article after the freezing step to reduce the temperature gradient; thawing the liquid portion of the solid ceramic article after the normalizing step; and evaporating the liquid portion of the solid ceramic article after the thawing step.

11 . The method of claim 1 , wherein the solid ceramic article is white in color, the method further comprising glazing the solid ceramic article with a clear glaze formulation that lacks colorants.

12 . The method of claim 11 , further comprising firing the solid ceramic article after the glazing step.

13 . A method of producing a ceramic product comprising:
freezing a liquid portion of a mixture in a mold to form a solid ceramic article; drying the solid ceramic article after the freezing step, the drying step comprising:
a normalizing stage in which the solid ceramic article is brought to a substantially uniform temperature near a thawing point of the liquid portion;
a thawing stage after the normalizing stage.

14 . The method of claim 13 , wherein at least a portion of the drying step is performed in a low humidity environment.

15 . The method of claim 13 , wherein the freezing step involves directing a cooling agent across the mold from a first surface to a second surface of the mold, the second surface of the mold including a vent.

16 . The method of claim 15 , wherein a first portion of the solid ceramic article positioned near the first surface of the mold is colder than a second portion of the solid ceramic article positioned near the second surface of the mold.

17 . The method of claim 13 , wherein a temperature of the normalizing stage is about 20° F. to about 30° F.

18 . The method of claim 17 , wherein the temperature of the normalizing stage is about 28° F.

19 . The method of claim 13 , wherein a duration of the normalizing stage is about 30 minutes or more.

20 . The method of claim 13 , wherein a temperature of the thawing stage is about 40° F. or more.

21 . The method of claim 13 , further comprising an evaporating stage after the thawing stage, wherein a temperature of the evaporating stage is about 200° F. or more.

22 . The method of claim 13 , further comprising:
glazing the solid ceramic article after the drying step with a clear glaze formulation that lacks colorants; and firing the solid ceramic article after the glazing step.

23 . A method of producing a ceramic product comprising:
introducing a mixture comprising a liquid portion into a mold having a first surface and a second surface with a vent; freezing the liquid portion of the mixture by directing a cooling agent across the mold from the first surface to the second surface to form a solid ceramic article; normalizing the solid ceramic article to a temperature near a thawing point of the liquid portion after the freezing step; and thawing the liquid portion of the solid ceramic article after the normalizing step.

24 . The method of claim 23 , wherein:
the normalizing step is performed at a temperature of about 20° F. to about 30° F.; and the thawing step is performed at a temperature of about 40° F. or more.

25 . The method of claim 23 , further comprising evaporating the liquid portion from the solid ceramic article after the thawing step, wherein the evaporating step is performed at a temperature of about 200° F. or more.

26 . The method of claim 23 , wherein:
after the freezing step, the solid ceramic article has a temperature gradient between a first portion of the solid ceramic article positioned near the first surface of the mold and a second portion of the solid ceramic article positioned near the second surface of the mold; and after the normalizing step, the solid ceramic article has a substantially uniform temperature without the temperature gradient.

Assignees

• Delta Faucet Co

Inventors

• Thomas Kurt J
• Bridgett Paul A V
• Veros Michael J
• Elmer Joseph A
• Dennis Nathanael

Classifications

• Y02P40/60

  Production of ceramic materials or ceramic elements, e.g. substitution of clay or shale by alternative raw materials, e.g. ashes · CPC title

• C04B2235/94

  Products characterised by their shape · CPC title

• C04B2235/606

  Drying · CPC title

• C04B2235/3208

  Calcium oxide or oxide-forming salts thereof, e.g. lime · CPC title

• C04B2235/3201

  Alkali metal oxides or oxide-forming salts thereof · CPC title