Mechanism and control of adhesion and dispersion of fine particles

随着初级颗粒尺寸的减小，极大地促进了难以分散的聚集体的形成。细颗粒的黏附和分散机理目前还不是很清楚，但从理论和实验两个方面进行了研究。主要结果简要总结如下1.研究了两种不同大小的球形颗粒间液桥的形成机理。根据液体中可溶杂质的浓度、颗粒直径和湿度可以定量地预测液桥分布和粘附力。在干燥过程中，可以通过调节可溶杂质的浓度来控制粉状物料的平衡含水率。液态盐桥干燥后残留的固体盐桥产生的粘附力是液体中初始盐浓度、干燥后颗粒直径和周围湿度的函数。阐明了水中凝聚颗粒在加速流和剪切流作用下的分散机理。在这种情况下，团聚颗粒的分散可以通过颗粒周围的表面电位和悬浮液的pH来控制。

Formation of aggregates difficult to disperse is considerably facilitated as the primary particle size decreases. The mechanisms of adhesion and dispersion of fine particles, which are far from being well understood, have been studied both theroretically and experimentally. The main results are breifly summarized below.1. The mechanism of formation of liquid bridges between two different-sized spherical particles has been examined. Both the liquid bridge profiles and the adhesion force can be quantitatively predicted from the concentration of soluble impurities in the liquid, the particle diameter and the humidity.2. In drying processes, the equilibrium moisture content of powdery materials can be controlled through adjustment of the concentration of soluble impurities.3. The adhesion force arising from the solid salt bridge remaining after drying of the liqued bridge is a function of the original concentration of salt in liquid, the particle diameter and the surrounding humidity after drying.4. The mechanism of dispersion of coagulated particles in water under acceleration and shear flow has also been clarified. In this case, dispersion of the agglomerated particles can be controlled by the surface potential around the particles and the pH of the suspension.