Patterned superhydrophobic metallic surfaces.

Area of Science:

• Materials Science
• Surface Science
• Tribology

Background:

• Superhydrophilic surfaces exhibit complete wetting.
• Superhydrophobic surfaces repel water, crucial for various applications.
• Controlling surface wettability is key in materials engineering.

Purpose of the Study:

• To investigate the wettability transition of metal alloys with dual scale roughness.
• To understand the role of surface morphology and chemistry in wettability changes.
• To correlate carbon content with the observed superhydrophobic behavior.

Main Methods:

• Femtosecond laser irradiation to create dual scale roughness structures.
• Contact angle measurements to quantify surface wettability.
• Surface analysis to determine chemical composition, focusing on carbon content.

Main Results:

• Metal alloys initially displayed superhydrophilicity after laser structuring.
• Surfaces transitioned to superhydrophobicity (contact angles > 150 degrees) over time.
• Contact angle hysteresis ranged from 2 to 6 degrees.
• Wettability change correlated with increased surface carbon content.

Conclusions:

• Dual scale roughness, induced by femtosecond laser irradiation, can lead to time-dependent wettability transitions.
• Surface chemistry, specifically carbon adsorption, plays a critical role in achieving superhydrophobicity.
• The combined effects of surface morphology and chemistry dictate the long-term wetting behavior of structured metal alloys.