粒径≤2μm的超细粉体颗粒分散方式探讨

Inquiring into dispersion mode of ultra-fine particles with grain size small than 2 μm

超细粉体随其颗粒粒度减小,自发团聚趋势更加明显。改善粉体的分散性是实现超细粉体分级的前提,也是实现工业化应用的关键。论文作者探讨了粉体团聚和分散的作用机理,分析、比较了超细粉体在空气中和液相中的分散方法及适用范围,认为对于粒径≤2μm的超细粉体,因颗粒间的范德华引力比重力大几百倍,因而不会因重力而分离,只宜采用在液相中分散的方法使之分散,其分散途径有:通过改变分散相与分散介质的性质来调控HAMAKER常数,使其值变小,颗粒间吸引力下降;调节电解质及定位离子的浓度,促使双电层厚度增加,增大颗粒间的排斥力;选用与分散颗粒和分散介质均具有较强亲和力的聚合物电解质,通过空间位阻和静电协同作用来达到优异的分散效果。

Ultra-fine particles have a tendency to reunion spontaneously with the decrease of their particle size. Improving particle dispersivity is regarded as the base of fi-actionation of ultra-fine particles, and the key to its industrial application. The mechanisms of agglomeration and dispersion of ultra-fine particles are discussed, dispersing methods and their applied fields of ultra-fine particles in atmosphere and liquid phases are analyzed and compared. It is recognized that the van der WAALS attractive force of the super-fine powder with grain size no more the 2 μm is hundreds times larger than its gravity force, so it is proposed that ultra-fine particles with a particle size no more than 2 μm should be dispersed in liquid with physical-chemical methods. Three approaches to improving the dispersion are as follows： 1） Change characters of dispersion phases and dispersion medium to control HAMAKER constant and absorption force between particles; 2） Adjust electrolyte and orientation ions concentrations to increase twi-electric layer thickness and repulsion force between particles; 3） Choose polymer electrolyte with good absorption force on both particle and dispersion medium to acquire excellent dispersion effect via strengthening the harmonious application between space force and static electric force.