Spherical Gamma Alumina Nano-powders Produced from Aluminium Salts Boehmite Sol by Spay-pyrolysis Processes

Spherical Alumina powders have been fabricated using a pilot-scale spay-pyrolysis (SP) device using Al (NO3)3 solution and boehmite sol. Spherical alumina powders with different sizes and microstructures are produced using aluminium salt solution and beohmite sol. The Al (NO3)3 -derived alumina powders have a broad sizer range (0.2∼70 μm) including e co-existing hollow particles with amorphous phase. For the alumina powders produced using boehmite sol under the fixed SP conditions, solid particles with an average diameter of 0.45 μm and narrow size distribution are obtained and the as-prepared alumina powder have gamma crystal phase. Furthermore, the boehmite-derived alumina has the spherical morphology with wrinkled structure formed with aggregates made of less 5nm nanocrystals. The difference in size and microstructures of Al (NO3)3 and boehmite sol-derived alumina products is attributed to the evaporation-precipitation-pyrolysis (EPP) mechanism for salt-derived process and the evaporation-aggregation-pyrolysis (EAP) for sol-derived process, respectively.