Apparatus for making nanostructured ceramic powders and whiskers

Abstract

An apparatus of forming non-agglomerated nanostructured ceramic (n-ceramic) powders from metalorganic precursors combines rapid thermal decomposition of a precursor/carrier gas stream in a hot tubular reactor with rapid condensation of the product particles on a cold substrate under a reduced inert gas pressure of 1-50 mbar. A wide variety of metalorganic precursors is available. The apparatus is particularly suitable for formation of n-SiC.sub.x N.sub.y powders from hexamethyl-disilizane or the formation of n-ZrO.sub.x C.sub.y powders from zirconium tertiary butoxide. The n-SiC.sub.x N.sub.y compounds can be further reacted to form SiC or Si.sub.3 N.sub.4 whiskers, individually or in random-weave form, by heating in a hydrogen or ammonia atmosphere. The non-agglomerated n-ceramic powders form uniformly dense powder compacts by cold pressing which can be sintered to theoretical density at temperatures as low as 0.5 Tm. By appropriate choice of precursor compound and carrier gas, this apparatus can be used to produce nanoosized powders of almost any desired material, including metals, intermetallics, semiconductors, superconductors, ferro-electrics, optically active materials and magnetic materials, as well as their composites.

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