Dispersion of Powders in Air and in Liquids
Dispersion of Powders in Air and in Liquids
复制标题
粉末在空气和液体中的分散
DOI：
10.1007/978-1-4020-9016-5_5
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
H. Merkus
中科院分区：
文献类型：
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作者：
H. Merkus
颗粒系统的粒度分布通常是针对含有单一、分散良好（初级）颗粒的系统进行测量。对于自由流动的粉末，简单的流动足以产生初级颗粒。对于有些粘性的粉末，在曲折通道中的空气分散可能就足够了。但通常需要在液体中分散，因为它提供了更多的途径来控制和优化分散过程。首先，用添加或不添加表面活性剂的合适液体润湿颗粒，降低了颗粒间的力。其次，搅拌器或超声波浴可以提供能量以将团簇分裂成初级粒子。第三，可以添加化学品以稳定分散体。最后，可以容易地评估分散体的质量。各种技术可用于直接评估或研究时间对分散体稳定性的影响。干燥粉末的不充分分散导致不完全的解聚，并因此导致粒径大于初级颗粒的粒径。在不充分稳定的分散体中，部分再附聚可能产生相同的效果。溶胀、溶解或破裂可在分散于液体期间提供其它解释问题。给出了一些诊断方法。
Particle size distributions of particulate systems are usually measured for systems containing single, well-dispersed (primary) particles. For free-flowing powders, simple flow suffices to give primary particles. For somewhat sticky powders, air dispersion in zigzag channels may suffice. But often dispersion in a liquid is required, as it provides more routes to control and optimize the dispersion process. First, wetting of the particles with a suitable liquid with or without an added surfactant, reduces the inter-particle forces. Secondly, a stirrer or an ultrasonic bath can supply energy to split clusters into primary particles. Thirdly, chemicals can be added to stabilize the dispersion. And finally, the quality of the dispersion can be easily evaluated. A variety of techniques is available for direct evaluation or for studying the effect of time on the stability of the dispersion. Inadequate dispersion of dry powders leads to incomplete de-agglomeration and, thus, to particle sizes larger than that of the primary particles. The same effect may come from partial re-agglomeration in insufficiently stabilized dispersions. Swelling, dissolution or breakage may provide other interpretation issues during dispersion in liquids. Some means for diagnosis are given.