소수성 텍스쳐 표면에 충돌한 단일 액적의 퍼짐 및 고착 특성

Abstract

The present study conducts experimental investigation on spreading and deposition characteristics of a 4.3 μl de-ionized (DI) water droplet impacting upon aluminum (Al 6061) flat and textured surfaces. The micro-textured surface consisted the micro-hole arrays (hole diameter: 125 μm, hole depth: 125 μm) fabricated by the conventional micro-computer numerical control (μ-CNC) milling machine process. We examined the surface effect of texture area fraction φs ranging from 0 to 0.57 and impact velocity of droplet ranging from 0.40 to 1.45 m/s on spreading and deposition characteristics from captured images. We used a high-speed camera to capture sequential images for investigate spreading characteristics and the image sensor to capture image of final equilibrium deposition droplet for analyze spreading diameter and contact angle. We found that the deposition droplet on textured surfaces have different wetting states. When the impact velocity is low, the non-wetting state partially exists, whereas over 0.64 m/s of impact velocity, totally wetting state is more prominent due to the increase kinetic energy of impinging droplet.