High strength porous alumina by spark plasma sintering

High strength porous alumina was fabricated by spark plasma sintering (SPS) at temperatures between 1000 and 1200 degrees C with nanocrystalline Al(OH)(3) as the starting powder without any seeds, dopants or inclusions. Decomposition of the Al(OH)(3) produced a series of transitional alumina phases depending on sintering temperature and pressure and finally the stable alpha-alumina phase was obtained. A network of continuous pores with unimodal pore size distribution was estimated by mercury porosimetry and BET Surface area measurements, with the porosity ranging between 20% and 60% based on sintering conditions. Predominance of fine grains and extensive necking between them led to better strength in the sintered samples. The bending strength of the sintered compacts rapidly increased with sintering temperature while retaining reasonable porosity suitable for practical applications. The results clearly indicate that in situ phase formation of alpha-Al(2)O(3) and theta-Al(2)O(3) provides strength and porosity, respectively. Phase trans formation, pore morphology and microstructure evolution were also studied. (C) 2008 Elsevier Ltd. All rights reserved.