Synthesis and Processing of Nano-α-Al_2O_3 Powders

摘要

Nano-corundum powders have been synthesised for use as raw materials in advanced ceramic technologies or as CMP polishing agent. The approach avoids the formation of platelet-shaped boehmite. Instead, a quasi- amorphous precursor obtained from different (inorganic or organic) sources gives equiaxed alumina particles and ex- hibits a reduced activation energy for the final transformation to corundum. Seeding with α-Al_2O_3 or diaspore reduces the transformation temperature to 800-900℃. Depending on seeds, the size of the obtained individual, re-dispersed nano-corundum particles is 25-100 nm. The sintering behaviour of these nano-powders is significantly affected by processing, it depends on the purity of raw materials and processes (e.g. impurities from wear on ball milling), on the particle size and the amount of seeds.