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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

粒度控制起着至关重要的作用，因为最终的材料性能通常取决于初级颗粒的尺寸。均匀成核在过去已被广泛研究。然而，现有理论的复杂性阻碍了其在材料制造等应用领域的实际应用。因此，除了经典的成核理论，模型，使准确估计的数量浓度和平均尺寸的成核粒子的操作条件和物料性能的函数已被提出。液相成核实验中，银颗粒产生的化学还原方法已成功地证实了该模型的预测。本研究的目的是检查以前的模型的有效性，使用各种方法的颗粒形成。所得结果可概述如下。在第一年，单体扩散系数对 ...更多信息对于其中银颗粒通过液相中的还原方法产生的系统，研究了颗粒产生，其是包括在先前模型中的因素之一。通过添加增稠剂改变溶液的粘度来控制单体扩散系数，并且实验发现所产生的颗粒的数量浓度与导致颗粒尺寸减小的单体扩散系数成反比，这定量地支持了模型。在第二年，我们用一个简单而实用的均匀成核模型研究了凝结水汽形成气溶胶粒子的机理。该模型，这是一个扩展的动力学制度的模型先前开发的，并成功地测试了液相均质成核，允许可靠的估计所产生的颗粒的平均尺寸和数量浓度作为材料性能和操作条件的函数。考虑扩散损失和壁面凝结的模型预测与实验结果吻合得很好。少