Multifunctional aluminium surfaces – Laser-structured micropatterns with ice-repellent, superhydrophobic and easy-to-clean properties

Abstract

In this work, the fabrication of multifunctional periodic microstructures on pure aluminium is presented. Three different geometries were fabricated with feature sizes ranging between 7 µm and 50 µm by using laser-based microstructuring methods. In detail, nanosecond pulsed direct laser writing and picosecond pulsed direct laser interference patterning were used with infrared laser radiation. The wetting characteristics of these structures were investigated performing static water contact angle measurements as well as by measuring the contact angle hysteresis and the sliding angle. The final wetting results show constant static contact angles above 150°, permitting the water droplets to roll off the substrate as well as collecting contamination at the same time. This self-cleaning effect led to a reduction of up to 94% of the spread of 1 µm sized manganese oxide particles. In addition, the freezing time required for droplets laying on the patterned surfaces was increased nearly by 300% at a temperature of 20 °C below zero. Finally, the results are compared to finite element simulations of heat transfer.