Battelle Memorial Institute

Beebhas C Mutsuddy

Roger R Wills

Peter J Melling

Jagadish C Debsikdar

Ibrahim Sekercioglu

Marion Brockway

Process for producing high purity aluminum nitride powder by reacting aluminum sulfide with gaseous ammonia at an intermediate temperature (about 700.degree. C.) and holding at that temperature until an intermediate product (Al.sub.x N.sub.y S.sub.z) is formed where x, y, and z are integers; then further heating to a temperature above 1100.degree. C. and reacting with gaseous ammonia. A high purity, low oxygen containing, free flowing powder is produced. A posttreatment using a carbon source such as graphite further reduces the oxygen content. The oxygen content can be further reduced by reacting the aluminum nitride formed with carbon at about 1600.degree. C.

Process for preparing high purity aluminum nitride

A process for producing toughened ceramic composites from ceramic precursor materials by forming microcomposite particles from the ceramic precursor materials to produce microstructures that impart enhanced toughness to the particles. The microcomposite particles are consolidated at a pressure, a temperature and for a time sufficient to form bulk ceramic components that exhibit the general microstructure and toughness of the microcomposite particles while the temperature is maintained above that where particle consolidation occurs but below the eutectic or melting temperature of the matrix. The consolidated product retains the toughness of the microcomposite particles.

Process for producing ceramic composites from microcomposite particles

A beta and beta'-alumina precursor sol is prepared by controlled hydrolysis of chelated aluminum alkoxide in an alcohol solvent and, subsequently reacting it with a mixture of sodium, magnesium, and lithium alkoxides or acetates or a mixture thereof. The sol thus obtained can be converted into an amorphous transparent gel at low temperatures. This amorphous gel, crystallizes directly into crystalline beta-aluminas at about 1020.degree. C. On heating to about this temperature, crystalline beta and beta'-alumina are formed which are useful as solid electrolyte material in making a sodium-sulfur battery.

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Lancaster, OH, United States of America

Beebhas C Mutsuddy