Development for New Method of Preparation of Fine particles utilizing Splashing phenomena in Molten Metal with Ammonia gas.

点击翻译按钮获取中文摘要

In previous studies on evaporation of molten metals in reactive gas flows, it was found that molten copper was splashed when it was held in ammonia gas. The splashing phenomena gave me a new idea for producing fine metallic particles. Then I named the new method "ammonia splashing method." In this study, as a fundamental study on the preparation of the fine particles with the ammonia splashing method, the splashing behavior of molten metals that were held in ammonia gas flows was investigated in order to clarify the effects of the temperature of the molten alloy, the content of the alloying element, ammonia gas flow rate, and the molar fraction of ammonia in gas mixture on both the rate of splash, i.e. the production rate, and characteristics of the obtained particles.Molten pure silver, lead and bismuth were not splashed, but molten copper and tin were splashed. The splash rates of copper-tin, -silver, -lead alloys and tin-silver, - bismuth, -lead, -copper alloys decreased with increasing the content of alloying element. The rate of splash increased with increasing ammonia gas flow rate and with rising the temperature of molten alloy. The rate of splash in ammonia + hydrogen gas mixture was larger than that in ammonia + argon and + nitrogen. The rate of splash increased with molar fraction of ammonia in the gas mixtures.The gotten particles by the splash were spheric and metallic, The size of the particles ranged to 0.1 - 150 mu m. The particles with relatively large size had cavities. The mean particle diameter of the particles increased with increasing the content of alloying element and with rising the temperature of the molten alloy. Also, it increased with increasing the distance between the melt surface the and the tip of the lance for introduction of ammonia.