Production of Ultra Fine Particles by Gas Evaporation Technique

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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.