Low Temperature Sintering of Bimodal Alumina Powder Mixtures with Nanocrystalline Component

Nanocrystalline α-Al2O3 powder was prepared by a wet-chemical method calcining the dry NH4Al(OH)2CO3 precursor synthesized from NH4Al(SO4)2 and NH4HCO3. Alumina ceramics were fabricated by pressureless sintering process at 1450℃ from bimodal alumina powder mixtures with the prepared nanocrystalline component using MgO and SiO2 as additives. The effect of nanocrystalline α-Al2O3 component on alumina ceramics was also studied. The materials fabricated have better mechanical properties.