Al_2O_3包覆SiO_2球形复合粉体的制备及烧结

Preparation and Sintering of Al_2O_3-coated SiO_2 Spherical Composite Powders

以Na2SiO3·9H2O、浓H2SO4等为原料,采用溶胶凝胶—喷雾干燥法制备球形二氧化硅,并采用非均匀成核的方式对其进行表面包覆氧化铝的处理,进而研究在不同温度煅烧下包覆样品的形貌、组织成分、粒度及分散性的改变。通过X射线衍射仪,扫描电子显微镜,激光粒度分析仪,能谱仪等对包覆前后以及不同温度烧结后的样品进行表征。结果表明:采用非均匀成核法,Al2O3以无定形结构成功的包覆在球形SiO2粉体表面。样品在1100℃发生莫来石转变,并在1400℃非晶SiO2转变为方石英,同时莫来石转变完全。

Spherical silica was prepared from Na2SiO3· 9H2O and oil of vitriol by sol-gel spray drying process method, and it was coated with aluminum oxide using the heterogeneous nucleation process. Then the effects of different calcinations temperatures on morphology, constituent, particle size and dispersity of the coated sample were studied. Also, X-ray diffractometer （XRD） , scanning electron microscope （SEM）, laser particle size analyzer （LPSA） and energy disperse spectroscopy （EDS） were used to characterize the sintered samples with or without coating. The results show that, Al2O3 can be successfully coated on the surface of spherical silica powder with amorphous structures. Mullite began to transform when the temperature reaches 1100 ℃. In addition, in the temperature of 1400 ℃ ,amorphous SiO2 can be turned into cristobalite and mullite transformation has completed.