Synthesis and Processing of Nano-alpha-Al2O3 Powders

A new nanosynthesis gives corundum (alpha-Al2O3) powders with a redispersible particle size of (e.g.) 40 nm. Avoiding the intermediate formation of platelet-shaped boehmite, the corundum particles exhibit an equiaxed shape. Key issues are the regime of controlled hydrolysis and the nature of seeds where nanoscale diaspore, prepared by a new hydrothermal synthesis, was most efficient. Apart from its particle size, the sintering performance of the nanocorundum was observed to depend strongly on the purity of the powder.