Effect of aluminum sources and pH value on preparation of α-Al2O3 powders by sol-gel method
In this paper,α-Al2O3 powder with regular morphology was prepared by the sol-gel method using aluminum sulfate,aluminum nitrate and ammonia water as raw materials.The effects of different mass ratios of aluminum salts and the pH value of the solution on the phase composition,morphology and dispersibility of the alumina powder were systematically studied by X-ray diffractometer(XRD),scanning electron microscope(SEM),thermogravimetric-differential scanning calorimeter(TG-DSC)and Fourier transform infrared spectrometer(FTIR).The results show that the dispersibility and morphology of the α-Al2O3 powder can be changed by adjusting the mass ratio of aluminum nitrate and aluminum sulfate.The addition of sulfate ions makes the aluminum hydroxide precursor transform into the boehmite phase,and the prepared α-Al2O3 powder has a regular morphology.With the increase of the pH value,the precursor phase changes from amorphous aluminum hydroxide to the bayer-ite phase through the boehmite phase,and the prepared α-Al2O3 powder is seriously agglomerated.When the mass fractions of aluminum nitrate and aluminum sulfate are 75%and 25%respectively,the pH value of the solution is 7,and the precursor is heat-ed at 1200℃for 2 h,the α-Al2O3 powder with good dispersibility and regular morphology can be prepared.
α-Al2O3sol-gel methodmicrostructureparticle size distribution
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