Preparation Of Novel Flaky Alumina And Its Application In Pearlescent Pigment

The flaky alumina has been widely used in the fields of polymer, ceramic, pearlescent pigment because of its special plate-like structure and excellent physical and chemical properties. The flaky alumina was successfully prepared by the molten salt synthesis method, and measured by means of microscope, X-Ray diffraction, laser diffraction instrument and scanning electron microscope in order to investigate the factors in the process of preparation, such as alumina source, molten salts, temperature and time of calcination, seeds etc. It was found that flaky alumina powders with thickness of 200-500nm, diameter of 10-40μm and bigger than 40 in aspect ratio, could be synthesized at 1100℃for 5 hours when the mole ratio of Al2(SO4)3 to mixture molten salts (NaF:KF=1:1) was 10:1, and the additive amount of phosphate and titania were 1% and 1%(based on alumina by mol) respectively. The flaky alumina was also suitable for the use of pearlescent pigment after trial of coating TiO2 on it. The crystal growth mechanism of flaky alumina was also studied, which is useful to control the crystal growth of alumina in molten salts.