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Preparation of ultrafine spherical AlOOH and Al₂O₃ powders by aqueous precipitation method with mixed surfactants

Kong, Jian, Chao, Bingxuan, Wang, Teng, Yan, Yulong
Powder technology 2012 v.229 pp. 7-16
Fourier transform infrared spectroscopy, aluminum chloride, aluminum oxide, aluminum sulfate, powders, sodium chloride, stearic acid, surfactants, thermogravimetry, urea
Ultrafine spherical boehmite (AlOOH) particles were prepared from aluminum sulfate and aluminum chloride solution with urea as precipitant at 90°C. It was observed that mixed surfactants tween80-sodium stearate could improve dispersion of AlOOH particles. While the concentrations of tween80 and sodium stearate were 0.75wt.% and 0.14wt.% respectively, particles with spherical degree of 1.1 and size of 0.36μm could be achieved. The thermogravimetric (TG) and Fourier transform infrared spectroscopy (FTIR) showed that sodium stearate molecules were bonded upon the surface of particles forming a coating layer to prevent agglomeration. Addition of NaCl could further improve dispersion of particles, spherical AlOOH particles with average size of 0.38μm and nanosized spherical particles could be obtained when the concentration of NaCl was 0.05M and 0.1M. At the same time, Al₂O₃ powders obtained from precursor with NaCl showed much better sintering behavior.