MECHANISM OF PARTICLE FORMATION BY HOMOGENEOUS AND HETEROGENEOUS NUCLEATIONS IN GAS-PHASE, LIQUID-PHASE AND SOLID-PHASE

气相、液相和固相均质和异质成核颗粒形成机制

基本信息

批准号：
10650752
负责人：
KOUSAKA Yasuo
金额：
$ 2.24万
依托单位：
OSAKA PREFECTURE UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

Control of particle size plays a critical role because the final material properties usually depend on the size of the primary particles. Homogeneous nucleation has been extensively studied in the past. However, the complexity of the available theory prevents its practical use in applied fields such as materials manufacturing. Thus apart from the classical thermodynamical theories on nucleation, the model which enables accurate estimation of the number concentration and average size of the nucleated particles as a function of the operating conditions and materiel properties has been proposed. Liquid-phase nucleation experiments in which silver particles were generated by a chemical reduction method have successfully confirmed the predictions of the model. The objective of this research is to check the validity of the previous model, using various method of particle formation. The results obtained can be summarized below. At the first year, the effect of monomer diffusion coefficient on … More particle generation, which is one of the factors included in the previous model, was studied for systems where silver particles were generated by a reduction method in liquid phase. The monomer diffusion coefficient was controlled by changing viscosity of the solution by addition of a thickener, and it was found experimentally that the number concentration of particles generated was inversely proportional to monomer diffusion coefficient resulting in particle size reduction, which quantitatively supported the model. At the second year, the mechanism of aerosol particle formation from a condensing vapor is examined using a simple but practical homogeneous nucleation model. The model, which is an extension to the kinetic regime of a model previously developed and successfully tested for liquid-phase homogeneous nucleation, allows reliable estimation of the average size and number concentration of the generated particles as a function of material properties and operating conditions. The model predictions taken into accout for diffusion losses and wall condensation are in excellent agreement with the experimental results. Less

控制粒度的控制起着至关重要的作用，因为最终材料特性通常取决于主要颗粒的尺寸。过去，均匀的成核已经被广泛研究。但是，可用理论的复杂性阻止了其在诸如材料制造之类的应用领域中的实际使用。除了对成核的经典热力学理论之外，还提出了该模型可以准确估算核化颗粒的数量浓度和平均大小作为工作条件和材料特性的函数。通过化学还原方法产生银颗粒的液相核实验已成功证实了该模型的预测。这项研究的目的是使用各种粒子形成方法检查先前模型的有效性。获得的结果可以总结下面。在第一年，单体差异对…更多的粒子产生的影响（这是上一个模型中包含的因素之一）研究了用于在液相中通过还原方法产生的银颗粒的系统。通过添加增稠剂，通过溶液的变化粘度来控制核心的单体差，并且在实验上发现，产生的颗粒的数量与单体差成反比，从而导致粒度减少，从而定量支持该模型。第二年，使用简单但实用的均匀成核模型检查了从冷凝蒸气中形成气溶胶颗粒的机理。该模型是先前开发并成功测试的液相均匀成核模型的动力学状态的扩展，可靠地估计生成粒子的平均大小和数量浓度，这是材料特性和工作条件的函数。与实验结果相吻合，对扩散损失和壁凝结的ACCOUT进行了预测。较少的