Particle distribution on interface effect on capillary force and cracking during drying of colloidal dispersion film

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K20410
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0301:Mechanics of materials, production engineering, design engineering, fluid engineering, thermal engineering, mechanical dynamics, robotics, aerospace engineering, marine and maritime engineering, and related fields
• Research Institution: Sanjo City University
• Principal Investigator: WAKAKI Shiro 三条市立大学, 工学部, 助教 (80912261)
• Project Period (FY): 2021-08-30 – 2023-03-31
• Keywords: 粒子分散液 / 表面張力 / 薄膜 / 乾燥 / き裂欠陥 / 可視化

Outline of Final Research Achievements

Focusing on particles at the surface of the particle dispersion, we evaluated the effect of particles at the surface on the capillary force and measured the volume fraction of the particle near the gas-liquid-solid three-phase interface during colloidal dispersion film drying. The results showed that the position and order of the particles had a significant effect on the capillary force (Laplace pressure). The volume fraction of particles was not constant in the direction perpendicular to the crack direction, as shown the sparse and dense distribution. This sparse and dense distribution is considered to be caused by thermodynamic and hydrodynamic instabilities due to gradients in temperature, concentration, and interfacial tension. And a detailed study of this volume fraction distribution will help to clarify the crack mechanism.

Free Research Field

流体工学

Academic Significance and Societal Importance of the Research Achievements

薄膜製造技術を理解し開発する上で，粒子分散系の表面物性の評価とその体系化が求められており，非常に重要な研究課題である．これまで液表面に粒子が存在する系における
表面張力は，連続体として観察し測定した値や単純に分散媒の表面張力を元にした議論がほとんどであるが，本研究結果から分散粒子のサイズ，体積分率，表面における粒子の存在位置（粒子間距離，基板との距離など）などの因子が複雑に絡み合う問題であることが実験的に明らかになった，粒子分散系の界面科学という学術領域だけでなく，薄膜形成技術やフィラーを含むプラスチック材の流動シミュレーションなど様々産業分野にも応用できる知見であると考える．