摘要：本文讨论了用超临界流体干燥混凝胶制备氧化铝超细粒子的影响因素；一类为超临界流体的影响因素．其甲温度和压力具有明显的影响，有一较台适的超临界温度达最大比表面积；但超临界压力越低，比表面积越大。加热速率几乎没有影响。另一类为制备混凝胶的影响因素，包括水解温度、加水比例．异丙醇铝固体浓度等均有一最佳制备条件。

关键词：超临界流体干燥；氧化铝；超细粒子；混凝胶

Abstract:Two kind of factors which influence the surface areas of the alumina ultrafine particles have been discussed, One of the influence factors is the supercritical condition,The temperature and the pressure have the obvious effects on the surface areas of the alumina ultrafine particles.The conventional temperature for the high surface area of the alumina ultrafine particle is about 553K.With thedecreasing pressure of the supercritical condition,the surface areas of the alumina ultrafine particles increase The other of the influence factors of the alumina hydrogel preparation, such as the hydrolysis temperature ,the ratios of the water , the con-centrations of the aluminun isopiopoxide.

Keywords : supercrical drying ，wet gel,alumina，ultrafine particle