Development of Equipment Generating Ultra-fine particle for Functionally Gradient Materials.

1990年，对超细粒子(UFP)的形成进行了两项研究。一种是在直流电弧阳极上对金属(Ti，Al)衬底进行处理，形成UFP。研究了以氮气和氢气为反应气体的两种情况下，等离子体支撑气体的反应产物和形成条件。二是射频Ar等离子体和铝粉系统，它与添加到Ar等离子体气体中的氧气发生反应。这是用类似于液滴燃烧的模型进行的。用我们的方法开发功能梯度材料(FGM)存在两个主要问题：UFP的产率低和成分的平滑梯度。1991年，这些主要是关于铝颗粒和Ar/O2射频等离子体流系统的研究。前者是通过对流场的数值求解和超细颗粒粘壁的估算来推测的，并采用了反应管设计来获得较高的产率。此外，当使用氧气作为鞘气体时，鞘气体沿反应管壁流动，并获得较高的产率。后者，特别是金属与陶瓷的比例(这里是铝与氧化铝的比例)是通过调整添加到等离子体和/或鞘气体中的氧气的流量来解决的。生成的氧化铝有α-氧化铝、伽马-氧化铝、三角洲氧化铝、草酸-氧化铝。这些成分在大多数情况下是相当恒定的。这一施工控制有待今后进一步解决。

In 1990, two studies were constructed for formation of ultra-fine particle (UFP). One was the formation of UFP with treatment of metal (Ti, AI) substrate on the anode of a dc arc discharge. The products and conditions of the formation were studied in two cases adding nitrogen or hydrogen as a reactive gas to the plasma supporting argon gas. Two was rf argon plasma and al-uminum powder system which reacts with oxygen added to the argon plasma gas. This was carried out numerically with the model similar to a combustion of liquid droplet.There are two major problems in the development of functionally gradient material (FGM) with our method ; low yield of UFP and smooth gradient of composition. In 1991, these were mostly examined about the system of aluminum particle and argon/oxygen rf plasma flow. The former was speculated by numerical solution about the flow fields and estimation of ultra-fine particle sticking to wall, and a reaction tube design was adopted for a high yield. Moreover, a sheath gas flew along the reaction tube wall and got a high yield when oxygen gas was used as a sheath gas. The latter, particularly metal to ceramics ratio (here, aluminum to alumina) was solved by adjustment of the flow rate of oxygen addition to the plasma and/or sheath gases. Produced alumina were alpha, gamma, delta, rheta-alumina. These composition was fairly constant in the most cases. This construction control still remain to be solved in future.