摘要：为了研究纳米颗粒在火焰中的形成机理,基于电子低压撞击器建立燃烧法合成纳米颗粒的在线表征系统。在扩散火焰中通过氧化六甲基二硅氧烷蒸气制备二氧化硅纳米颗粒;使用该表征系统研究火焰底部、中部和上部的颗粒的粒子数浓度和粒径的关系,提出燃烧法合成纳米颗粒的可能的形成机理。结果表明:火焰区域可以分为化学反应区、凝并区和聚集区。颗粒历经化学反应、成核、凝并、团聚而形成最终颗粒。

关键词： 二氧化硅；纳米颗粒；燃烧合成;形成机制

Abstract： In order to study the formation mechanism of nano -particles synthesized in flames， an online characteristic system based on electrical low pressure impactor was set up. Silica nano-particles were synthesized by oxidation of the vapor of hexamethyl-disiloxane in diffusion flames. Using the characteristic mechanism， the relations between particle number density and particle size in the bottom， middle and top part of flame were studied. A possible flame synthesis nano-particles formation mechanism was presented. The results showed that the flames could be distinguished chemical reaction area， coalescence area and coagulation area， and particles experienced chemical reaction， nucleation， coalescence and coagulation to arrive final forms. 

Keywords：silica； nano-particles； flame synthesis； formation mechanism