Synthesis of porous Al2O3 ceramic clusters by surface hydrolysis of a thin Al-metal plate in water

Porous Al2O3 ceramic clusters are synthesized using a new chemical method involving an electrochemical surface hydrolysis of a thin Al-plate (of surface catalyzed with Hg2+-cations) in a pure water at room temperature. This is a highly exothermic self-induced spontaneous surface reaction which occurs very fast. As a result, it yields a highly porous AlO(OH)·αH2O precursor powder of hydrolyzed Al-metal of porosity as small as 18% and an average crystallite size of 30 nm. The value of α=0.70 is determined by thermogravimetric analysis of its desorption into Al2O3. The latter involves an enhanced porosity, as much as 40%, with as small particles or pores as of an average of 3–5 nm diameter according to the desorption temperature and other experimental conditions. The results are discussed with microstructure and X-ray powder diffraction studies.