纳米粉体大气环境团聚机理及无团聚纳米粉体的制备

Agglomerate mechanism of nanometer powders in atmosphere and methods of preparation of nan-agglomerate nanometer powders

分析了纳米粉体的表面结构与粉体间相互作用,研究了大气环境下纳米粉体的团聚机理及防止纳米粉体团聚的方法。研究结果表明:高的比表面积和表面能是纳米粉体团聚的强大动力,但常温下洁净粉体表面的本身结构调整不会导致纳米粉体团聚,只会导致其分散;外来物质(如空气、水等)在表面发生化学吸附与化学反应后,改变了表面结构和相互作用性质,在粉体表面生成具有羟基等新结构,导致粉体间相互吸引(如氢键间的作用力)与化学反应(如—OH基间聚合反应)等行为,是大多数纳米粉体团聚的真正原因。此外,还从原理上论述了真空状态、惰性气体保护及表面改性适合于无团聚纳米粉体的制备方法。

Agglomerate mechanism of nanometer powders was studied by analysing the surface structure and the interaction between powders in atmosphere. The results show that the adjustment of surface structure on the clean nanometer powders does not cause agglomeration but dispersion, although high specific area and surface energy are the main power of agglomeration. A new surface structure with hydroxyls(-OH) is formed while chemical adsorption and chemical reaction occure due to outside substance such as air and water. The attraction between nanometer powders because of the action between the hydroxyls(—OH) and the chemical reaction of the hydroxyls are the principal reasons of serious agglomeration of nanometer powders in atmosphere. The methods and mechanisms of preparation of non-agglomerative nanometer powders are disscussed. Vacuum, inert gas treatment and surface modification are suitable for preparation of non-agglomerate nano-powders.