A method for the preparation of porous needle-shaped mullite bodies

摘要

Needle-shaped mullite bodies are placed in a two-stage firing procedure, in which a green body initially to form a fluorotopaz and then is converted to acicular mullite. The bodies are in an enclosed area of the furnace installation contain. During the step of the fluorine-topaz-education a process gas stream is provided through the enclosed area. The process gas is a plurality of inlet openings at at least one side of the enclosed area and initiated by a plurality of outflow openings on another side of the enclosed area is drawn off. During the step of the formation of the needle-like mullite, a purge gas flow in the outer section of the furnace installation maintained. By this scavenging gas can flow from the latter into the enclosed area of the furnace installation and be removed from the furnace installation.