It is important for porous ultrafine particle to be dried in the preparation, thesupercriti-cal fluid and the frozen drying are the two methods to eliminate the surface tension, the sketch of the porous utrafine has been kept. The process and influence factors of two methods have been studied.

Key Words:Superoritical drying,frozen drying,porous ultrafine particle.

DOI：0.13732/j. issn. 1008-5548.1995.05.006

CLC No:Vol.1,No.3,18-25