Wettability Modification by Laser Processing
We have developed an inexpensive high-throughput laser-based nanostructuring process to transform metal surfaces to achieve multi-functionalities that combine tunable wettability, self-cleaning, and anti-reflectivity.
The wettability of the nanostructured surface was tuned from superhydrophobicity to superhydrophilicity by controlling the surface nanostructures and chemistry. The final wetting performance of laser-textured surfaces is a complex combination of surface micro/nanostructures and chemistry. We developed a systematic design approach to modify the dispersive and non-dispersive components of surface chemistry of the same laser-textured metal alloys to achieve various extreme wettabilities for a target application. It demonstrates surface chemistry design to match different applications, including repelling water and oil, absorbing water and oil, and separating oil and water from a mixture. We have shown that laser-textured surfaces can have enhanced properties in different application environments, such as:
- Enhanced anti-icing behavior
- Light-absorbing capability in visible and infrared spectra
- Excellent corrosion protection
- Selective catalytic activity
Wettability Patterning
By carefully controlling the surface chemistry and surface structure, we developed a maskless laser-based processing technique to fabricate a patterned wetting surface where alternating water affinitive and repellant regions co-exist side by side. Wettability-patterned surfaces have shown the potential for efficient fog harvesting for drinking water.
Friction stir processing to improve mechanical properties
Friction stir processing (FSP) is used on thin-wall high-pressure die cast (HPDC) parts to induce microstructural change locally. FSP eliminates porosity and breaks down detrimental microstructural phases, yielding a refined, homogeneous distribution. An intense thermomechanical event produced severe plastic deformation at high temperatures, resulting in dynamic recrystallization that yielded microstructural change. The FSP-driven microstructural refinement and porosity reduction improve yield strength, ductility, and high-cycle fatigue life.
