The Preparation And Application Of Al₂O₃ Sol

The Al2O3 sol was preprated by uniform precipitation method and using AlCl3·6H2O as the raw material. The effect of precipitation temperature, the pH value, the AlCl3 concentration, the species and dosage of peptizer and the surface active agent on the crystal form, stability, solidity and the particle size and distribution of the Al2O3 sol was tested by the numbers. And the reasonable preparation process parameters of Al2O3 sol was determined though the above analysis. The Al2O3 gel powder was obtained by the spray-drying method, and then we applied the powder in the Al2O3-MgO castable to research the effect of the powder on the castable performance. The main conclusions were as follows:1. We can obtain different outcomes if the temperature of precipitation is different. When the temperature was below 20℃, mainly the product was gibbsite, when between 20℃and 80℃, the outcomes was the gibbsite and boehmite, when the temperature was above 80℃, the product was almost boehmite.2. The higher the pH value and the higher the crystallization is.3. The addition of a certain amount of PEG400 during the preparation process can change the distribution of the sol powder from 8.7nm to 87.3nm and change the median diameter from 24.0nm to 6.4nm.4. The surface active agent PEG400 can regulate the stability of Al2O3 sol by the way of changing theζ-electric potential of the sol particle surface. Theζ-electric potential of the sol particle surface can increase 5~10mV at the range of 4~6 pH value compared to the samples that had no surface active agent.5. We can gain a blue transparent steady sol when control the rations between 0.20~0.25.6. The solid content increase with the increase of the salt concentration; and also the temperature of the precipitation reaction has effect on the solid content, the higher the temperature, the larger the solid content.7. Al2O3 gel powder was produced by the spray-drying method. The powder is something like pie or circular ring, the particle size is between 0.035μm and 28.75μm, and the median diameter and the surface area of the powder is 3.98μm and 391m2/g respectively. The crystal transformation process is AlOOH amorphous-Al2O3γ-Al2O3θ-Al2O3α-Al2O3 during calcined.8.The gel powder can promote castable sintering process, and research shows that the gel powder which was enjoined 3wt% and calcined at 600℃can enhance the normal strength and elevated temperature strength.9. The join of gel powder can promote the ratio of less than 10μm microporous and the pore volume, and also the spinel process, which improve the slag resistance of the castable. But excessive amount of gel can make the corundum powder consumption greatly, which reduce erosion resistance performance of samples.