Srećković T, Bernik S, Ceh M, Vojisavljević K
Department for Material Science and Energy Conversion, Institute for Multidisciplinary Research, Kneza Viseslava 1, 11030 Belgrade, Serbia.
J Microsc. 2008 Dec;232(3):639-42. doi: 10.1111/j.1365-2818.2008.02131.x.
In this paper, changes of microstructural characteristics of disperse systems during mechanical activation of zinc oxide (ZnO) have been investigated. ZnO powder was activated by grinding in a planetary ball mill in a continuous regime in air during 300 min at the basic disc rotation speed of 320 rpm and rotation speed of bowls of 400 rpm but with various balls-to-powder mass ratios. During ball milling in a planetary ball mill, initial ZnO powder suffered high-energy impacts. These impacts are very strong, and large amounts of microstructural and structural defects were introduced in the milled powders. The morphology and dispersivity of particles and agglomerates of all powders were investigated by scanning electron microscopy and scanning transmission electron microscopy. The specific surface area of initial ZnO powder was determined as 3.60 m(2) g(-1) and it increased to 4.42 m(2) g(-1) in mechanically activated powders. An increase of the ball-to-powder mass ratio led to a decrease of particle dimensions as well as increased the tendency for joining into quite compact agglomerates, that is aggregates, compared with the very loose, soft initial agglomerates. The obtained results pointed out that activation of ZnO powders produces a highly disperse, nano-scaled mixture of small particles, that is crystallites with sizes in the range of 10-40 nm. Most of these particles are in the form of aggregates with dimensions of 0.3-0.1 mum. The crystallite and aggregate size strongly depend on milling conditions, that is ball-to-powder mass ratio, as shown in this investigation.
本文研究了氧化锌（ZnO）机械活化过程中分散体系微观结构特征的变化。在行星式球磨机中，于空气中以基本盘转速320 rpm和碗转速400 rpm连续研磨300分钟，对ZnO粉末进行活化，但球粉质量比不同。在行星式球磨机球磨过程中，初始ZnO粉末受到高能冲击。这些冲击非常强烈，在研磨后的粉末中引入了大量微观结构和结构缺陷。通过扫描电子显微镜和扫描透射电子显微镜研究了所有粉末颗粒和团聚体的形态及分散性。初始ZnO粉末的比表面积测定为3.60 m² g⁻¹，在机械活化粉末中增加到4.42 m² g⁻¹。与非常松散、柔软的初始团聚体相比，球粉质量比的增加导致颗粒尺寸减小，同时增加了形成相当紧密团聚体（即聚集体）的倾向。所得结果表明，ZnO粉末的活化产生了一种高度分散的、纳米级的小颗粒混合物，即尺寸在10 - 40 nm范围内的微晶。这些颗粒大多呈尺寸为0.3 - 0.1 µm的聚集体形式。如本研究所表明的，微晶和聚集体尺寸强烈依赖于球磨条件，即球粉质量比。
