학술지명 : ACS Applied Materials & Interfaces
발행국가 : 미국
발표일자 : 2012년 7월
SCI여부 : SCI
제목: One-Step Process for Superhydrophobic Metallic Surfaces by Wire Electrical Discharge Machining
저자: 배원규, 송기영, Rahmawan, 주종남, 김두곤, 정도관, 서갑양
내용: 와이어 방전가공을 이용하여 금속에 초소수성 표면을 직접 구현함.
We present a direct one-step method to fabricate dual-scale superhydrophobic metallic surfaces using wire electrical discharge machining (WEDM). A dual-scale structure was spontaneously formed by the nature of exfoliation characteristic of Al 7075 alloy surface during WEDM process. A primary microscale sinusoidal pattern was formed via a programmed WEDM process, with the wavelength in the range of 200 to 500 mu m. Notably, a secondary roughness in the form of microcraters (average roughness, Ra: 4.16 to 0.41 mu m) was generated during the exfoliation process without additional chemical treatment. The low surface energy of Al 7075 alloy. (gamma = 30.65 mJ/m(2)), together with the presence of dual-scale structures appears to contribute to the observed superhydrophobicity with a static contact angle of 156 degrees and a hysteresis less than 3 degrees. To explain the wetting characteristics on dual scale structures, we used a simple theoretical model. It was found that Cassie state is likely to present on the secondary roughness in all fabricated surfaces. On the other hand, either Wenzel or Cassie state can present on the primary roughness depending on the characteristic length of sinusoidal pattern. In an optimal condition of the serial cutting steps with applied powers of similar to 30 and similar to 8 kW, respectively, a stable, superhydrophobic metallic surface was created with a sinusoidal pattern of 500 mu m wavelength.