METHOD FOR MAKING POROUS MULLITE-CONTAINING COMPOSITES

摘要

Porous aluminum-containing ceramic bodies are treated to form acicular mullite crystals onto the surfaces of their pores. The crystalsare formed by contacting the body with a fluorine-containing gas or a source of both fluorine and silicon atoms to form fluorotopaz at the surface of the pores, and then decomposing the fluorotopaz to form acicular mullite crystals. This process allows the surface area of the ceramic body to be increased significantly while retaining the geometry (size, shape, general pore structure) of the starting body. The higher surface area makes the body more efficient as a particulate filter and also allows for easier introduction of catalytic materials.

主权项

1. A process for increasing the surface area of a starting porous aluminum-containing ceramic body, comprising
(a) contacting the pores of the starting porous aluminate-containing ceramic body with a gaseous fluorine-containing compound or, if the starting porous aluminate-containing ceramic body does not contain silicon, a gaseous source of silicon atoms and fluorine atoms, at a temperature from 700 to 1200° C. to form a fluorotopaz on at least a portion of the surface of the pores of the porous aluminate-containing ceramic body and then (b) heating the ceramic body to a temperature of 1000 to 1500° C. to convert the fluorotopaz to acicular mullite whiskers attached to the surfaces of the pores of the ceramic body.