Foamed ceramic bodies contg silicon nitride or carbide - produced by nitriding or carburising foamed silicon bodies

摘要

Foamed silicon-contg. ceramic bodies are produced by treating fine silicon powder (63 mu) with a diol. NaOH soln. (pref. 0.3-5% soln.); pouring the resulting stable foam into moulds; and firing in a N2-contg. atmos. to produce Si3N4-contg. bodies, or in a carburising atmos. to produce SiC bodies. These bodies can be used as heat- and sound-inulators, catalyst carriers, filters and heat-exchange elements. They can withstand very high temps. and thermal shocks. They are resistant to attack by most of aggressive media. The prodn. is relatively inexpensive. The cell structure can be easily controlled by properly adjusting the amt. of NaOH, water, silicon particle size, and the reaction time between the mixing and drying and, if necessary, adding foaming-promoting or -suppressing agents.