Production of Ultra Fine Particles by Gas Evaporation Technique

直径在10 ~ 100 nm之间的超细颗粒（UFP）具有上级的电磁特性和其它性能，因而成为开发新材料技术的热点。为了充分利用这一特性作为材料的一个要素，应结合操作条件开发UFP的高效制造技术，以控制颗粒在均匀的尺寸和密度。从这个角度来看，本研究已经进行了追求的基本机制，在气体蒸发技术，包括饱和金属蒸汽的自成核的过程中，颗粒生长，和颗粒收集的超微粒子生产。以下是从调查中得出的总结。在氩气流场中，采用Zn金属和电热舟系统进行了UFP的制备实验，通过实验研究了在不同的操作参数（如气压、金属温度、气体温度和气体流速）下，UFP的颗粒特性。2.考虑到温度场和质量场的相互作用，分析了粒子的生成过程，包括粒子的自成核、生长和收集等过程。通过与实验结果的对比，解析地阐明了超微粒子的产生和输运过程。并推导了超微粒子的生成速度和粒径与操作参数的关系。3.在此基础上，获得了UFP制造工艺的基本知识。

The ultra fine particles (UFP) between 10 to 100nm in diameter have so superior characteristics in electric magnetic and the other properties, that they can become the center of the attention to open up new material technology. To make the best use of this characteristics as an element of material, the high efficiency manufacturing technology of UFP should be developed in conjunction with the operating condition to control the particles at uniform size and density. From the standpoint,this study has been conducted to pursue the basic mechanism of UFP production in the gas evaporation techniques including the process of self-nucleation of saturated metal vapor, particle growth, and particle collection. The following are the summary deduced from the investigation.1. As the results of UFP manufacturing experiments in an Ar-gas flow field by using Zn metal and electric heating boat system, the particle characteristics were experimentally made clear in connection with the operating parameter such as the gas pressure, the metal and gas temperature, and the gas velocity. 2. The particle production, which consisted of the process such as self-nucleation, growing, and collection, was analyzed taking account of the interaction between the temperature and mass fields. As compared with the experimental results, the production and the transport process of UFP were clarified analytically. The production velocity and diameter of UFP were also deduced in relation to the operating parameter. 3. On the basis of the above findings, the fundamental knowledge of UFP manufacturing process was obtained.