Picosecond laser machined designed patterns with anti-ice effect

Micromachining using ultra short laser pulses (USLP) has evolved over the past years as a versatile tool for introducing functional features in surfaces at a micrometric and even at a sub wavelength scale. Being able to control the surface topography at this level provides a method to change the wetting behavior of a great number of materials. In most cases, when a surface has a natural tendency to be wetted (high surface energy), increasing its roughness will increase the spreading of water over it, and when it is naturally hydrophobic this roughness can dramatically enhance the water repellency. In this study, anti-ice properties of water repellent laser machined materials are investigated. Therefore, a stainless steel substrate (AISI 304L) has been textured with regular hatched patterns, using UV and green laser pulses of 6.7ps. In order to decrease the surface energy, a thin hydrophobic coating has been applied on top of these structures. Super-hydrophobic state has been reached for many of the samples, and small hysteresis values have been measured to confirm the socalled, self-cleaning, or “lotus effect” properties of the engineered surfaces.