Successive fragmentation of droplets for efficient particle production

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K21934
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 19:Fluid engineering, thermal engineering, and related fields
• Research Institution: Kyushu University
• Principal Investigator: Inoue Chihiro 九州大学, 工学研究院, 准教授 (70466788)
• Project Period (FY): 2019-06-28 – 2021-03-31
• Keywords: 液体金属 / 微粒子 / 液滴 / 分裂 / 表面張力 / 分子拡散 / 高速度可視化 / 温度計測

Outline of Final Research Achievements

For the efficient production of fine metal particles, we conducted research with the aim of evaluating the applicability to innovative particle production technology by identifying the conditions under which liquid metals successively fragment. First, using a high-speed camera, we clarified the behavior of metal particles that split while scattering and the quantitative temperature. Then, metal fine particles were collected and investigated in detail from a microscopic viewpoint using an electron microscope. As a result, we succeeded in obtaining the diameter of metal particles and the diameter of bubbles inside. Furthermore, by combining high-speed visualization and theoretical analysis, diffusion phenomenon inside the particles and generation of bubbles inside were found being important for chain splitting, and continuous condensed phase reaction at high temperature was necessary for fine particle production.

Free Research Field

航空宇宙熱流体

Academic Significance and Societal Importance of the Research Achievements

積層造形や粉末冶金に用いられる金属微粒子は，従来，高速の気体や水噴霧を溶融金属に衝突させて微粒化，冷却して製造する．このとき，個々の金属微粒子は1回しか分裂しないため，エネルギー効率が低い．この課題を解決するために，本研究では，液滴が繰り返し分裂する連鎖分裂現象を応用することを着想した．実験と理論解析を実施し，液体金属が連鎖的に分裂する条件を特定し，革新的な微粒子製造技術への適用性を評価した．