Crosslinked green body articles and method of manufacturing porous ceramic articles therefrom
The invention describes a high porosity ceramic article and method of manufacturing the same and intermediate dried honeycomb green body articles. The article may have a total porosity of at least about fifty-five percent, above sixty percent, or even above sixty-five percent. The method of manufacture includes mixing a ceramic-forming powder, an organic pore former, water, and a crosslinker. Drying causes a condensation reaction between the pore former and the crosslinker thereby forming a network within the green body that strengthens the green body and reduces cracking. The pore former may include starch or an activated cellulose compounds. Secondary pore forming agents, such as graphite may also be included.
1. A method for manufacturing a high porosity ceramic article, comprising the steps of:
mixing a ceramic powder, a crosslinkable pore forming agent, a crosslinker, and water;
forming the mixture into a green body;
drying the green body to remove substantially all of the water during which the pore forming agent and crosslinker react to form a network within the green body; and
firing the green body to obtain the ceramic article;
wherein the crosslinkable pore forming agent is selected from the group comprising starch, activated cellulose, and mixtures thereof;
wherein the crosslinker includes an amide group; and,
wherein the crosslinkable pore forming agent and crosslinker are volatilized during firing.
2. The method of claim 1 , wherein the pore forming agent and crosslinker react in a condensation reaction.
3. The method of claim 1 , wherein the crosslinkable pore forming agent includes a hydroxyl group.
4. The method of claim 1 , wherein the ceramic powder is selected from a group consisting of alumina, silica, clay, zirconia, magnesia, silicate, spinels, zeolites, titania, AT, silicon nitride, and silicon carbide and mixtures thereof.
5. The method of claim 1 , wherein the ceramic powder includes a grain size from 50 nm to 5000 microns.
6. The method of claim 1 , wherein mixing includes a second pore forming agent.
7. The method of claim 1 , wherein a total porosity of the ceramic article is at least about 55%.
8. The method of claim 7 , wherein a total porosity of the ceramic article is at least about 60%.
9. A method for manufacturing high porosity ceramic articles, comprising the steps of:
mixing a ceramic powder, starch, an amide-containing crosslinker, and water;
forming the mixture into a green body;
drying the green body to remove substantially all of the water during which the starch and the crosslinker undergo a condensation reaction to form a network within the green body; and
firing the green body to obtain the ceramic article.
10. The method of claim 9 , wherein the amide-containing crosslinker is present at 0.1-6 wt. % of the starch.
11. The method of claim 9 , wherein the mixing includes a second pore forming agent.
12. The method of claim 11 , wherein the second pore forming agent comprises graphite.
13. The method of claim 9 , wherein the step of drying the green body removes substantially all of the water in the green body.
14. The method of claim 9 , wherein a total porosity of the ceramic article is at least about 55%.