| abstract |
Ceramic foams possessing controlled permeability and uniformity are prepared by the impregnation of an open-celled organic polymer foam material possessing a predetermined permeability and resilience with a aqueous slurry of a thixotropic ceramic composition while shearing said slurry an amount sufficient to maximize said impregnation, and expelling excess slurry from said material by conducting at least two passes of said material through preset rollers to effect a temporary compression ranging from about 50 to 90% for the first pass and 70 to 90% for the second pass. The resulting material is then dried and heated to remove the organic foam component. The foams prepared in accordance with the present invention are useful as filters for molten aluminum. |