Mechanism and control of adhesion and dispersion of fine particles

随着初级粒度的减小，显著促进难以分散的聚集体的形成。细颗粒的粘附和分散机理目前还没有很好的认识，但人们已经从理论和实验两个方面对其进行了研究。主要结果概括如下：1.研究了两种不同粒径球形颗粒间液桥的形成机理。根据液体中可溶性杂质的浓度、颗粒的粒径和湿度，可以定量预测液桥的形态和粘附力.在干燥过程中，可以通过调节可溶性杂质的浓度来控制粉状物料的平衡含水率.由液体桥干燥后残留的固体盐桥产生的粘附力是液体中盐的原始浓度、颗粒直径和干燥后周围湿度的函数。并阐明了加速剪切流作用下凝聚颗粒在水中的分散机理。在这种情况下，可以通过颗粒周围的表面电势和悬浮液的pH来控制附聚颗粒的分散。

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.