摘要
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.
出处
《粉末冶金材料科学与工程》
EI
2007年第5期284-289,共6页
Materials Science and Engineering of Powder Metallurgy
基金
高等学校博士学科点专项科研基金资助项目(20060533004)
湖南省自然科学基金资助项目(06JJ4014)
关键词
超细粉体
分散
团聚
ultra-free particle
dispersion
agglomeration