Preparation of Ultrafine Lamellate Alumina Powder via Chemical Route

The coatings of ultrafine laminate alumina grains were synthesized via chemical route. First, Al₂O₃-sol was prepared with materials, including KAl (SO₄) ₂·12H₂O, molten KCl, TiO₂ and Na₂CO₃; next, the ultrasonic dispersed Al₂O₃-sol was roll-coated on the PET membrane pre-covered with soluble resin, and the Al₂O₃/PET composite membrane formed after microwave baking; and finally, Al₂O₃ powder was produced by calcining the eluted Al (OH) ₃ coatings at 1200℃ for 2 h The influence of the variables, including the molar-ratio of reactants, TiO₂-content and dispersion time on the shape/size of Al₂O₃ grains was investigated with X-ray diffraction and scanning electron microscopy. The results show that hexagonal lamellate α-Al₂O₃ grains, with average grain-size of 10 μm and aspectratio of 10, were fabricated under the optimized condition:Al-source to KCl molar-ratio of 1:4, TiO₂-content of 2%, ultrasonic dispersion time of 30 min and calcination temperature of 1200℃.