Simple fabrication approach for superhydrophobic and superoleophobic Al surface

• Superhydrophobic and superoleophobic Al surface is demonstrated.
• Simple microfabrication contains mechanical grinding, acid etching, and FOTS coating.
• Addition of grinding step improves the rolling behavior of droplets.
• Grinding process induces mechanical defects and accelerates etching reaction.

In this paper, a simple and low-cost fabrication method is demonstrated to make superhydrophobic and superoleophobic Aluminum (Al) surfaces. The Al surfaces have hierarchical structures mimicking the lotus leaf. The manufacturing process is easily performed via grinding, acid etching, and low surface tension chemical coating, in sequence. The wettability of the fabricated Al surfaces is characterized with several liquids having different surface tension energy such as water, diiodomethane, and hexadecane. The effects of grinding and acid etching on wettability are also investigated to enhance the superhydrophobicity and superoleophobicity of the Al surface. The grinding process makes the surface rough effectively and improves the wetting behavior. Especially, the ground sample prepared with a sandpaper of P1000 grade shows the highest static contact angle and lowest sliding angle among the fabricated samples. Even though the wetting properties are generally improved by increasing the acid etching time, the repellency of the liquids on the surface is saturated at 10 min of acid etching time. The morphology difference of Al surfaces is characterized by measurement of field-emission scanning electron microscope (FE-SEM). The hierarchical micro/nanostructures combined with chemical coating enable the Al surface to be superhydrophobic and superoleophobic.

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