超临界流体快速膨胀用于细颗粒包覆技术

研究超临界流体在快速膨胀过程中的热力学状态变化，超临界流体在喷嘴端部快速膨胀过程中温度急剧降低，在一定条件下，降低的温度与流体体积流率平方成线性关系。超临界流体在快速膨胀射流中产生数十纳米量级的微核颗粒，流体膨胀前温度对微核粒径有显著影响。通过超临界流体在流化床中的快速膨胀，使包覆剂微核在颗粒表面形成均匀的薄膜包覆，实现颗粒或颗粒中关键组分在溶剂中的控制释放。

A Novel Technology for Fine Particle Coating by Using Rapid Expansion of Supercritical Fluid Solution

The change,of thermodynamic state of the superoritical fluid in the rapid expansion process through a narrow nozzle has been studied. The rapid expansion of the supercritical fluid result in a significant temperature drop of the fluid at the nozzle outlet. The experimental experimental results have shown that the temperature drop is a linear function of the square of the fluid volume flow rate at certain condition. The ultrafine particles at an older of tens nanometer form in the expansion flow. The pre-expansion temperature of the supercritical fluid affects the size of the ultrafine particles significantly. By using the rapid expansion of the supercritical fluid solution, a uniform film forms through the nucleus deposition on the core particle surface in a fluidized bed. The release rate of the particle or the key composition dried by the particle in a solvent can be controlled.