Nanoporous alumina products and process for their preparation

摘要

Production of a nano-corundum comprises dissolving chlorine-free inorganic precursors as starting material in a liquid medium or processing to a sol; hydrolyzing the solution or sol by adding a base in a mole ratio of base: precursor of 1: 3; aging at 60-98[deg] C for 1-72 hours; drying and then calcining at 350-650[deg] C to convert the hydrolyzed precursor into a quasi-amorphous intermediate phase and subsequently into transitional alumina; and further calcining to convert into the corundum phase by raising the temperature to less than 950[deg] C. Independent claims are also included for: (1) a nano-corundum powder produced from the process having an average particle size distribution D 50of less than 100 nm; and (2) a process for coating porous or sealed metallic substrates, in which the particles of the hydrolyzed sol or the particles of a suspension of nano-corundum are electrophoretically deposited onto a metallic substrate and subsequently calcined.