Laser Fabrication of Anti-Icing Surfaces: A Review

Abstract

In numerous fields such as aerospace, the environment, and energy supply, ice generation and accretion represent a severe issue. For this reason, numerous methods have been developed for ice formation to be delayed and/or to inhibit ice adhesion to the substrates. Among them, laser micro/nanostructuring of surfaces aiming to obtain superhydrophobic behavior has been taken as a starting point for engineering substrates with anti-icing properties. In this review article, the key concept of surface wettability and its relationship with anti-icing is discussed. Furthermore, a comprehensive overview of the laser strategies to obtain superhydrophobic surfaces with anti-icing behavior is provided, from direct laser writing (DLW) to laser-induced periodic surface structuring (LIPSS), and direct laser interference patterning (DLIP). Micro-/nano-texturing of several materials is reviewed, from aluminum alloys to polymeric substrates.

Keywords: DLIP; LIPSS; anti-icing; direct laser writing; laser; metals; microstructuring; polymers; superhydrophobicity; wettability.

Figure 1

The statistics of the published articles indexed in Scopus (black line) and of the published patents listed in Espacenet [15] (black dotted line) on the topic of “anti-icing”. Year range selected: 1988–2019.

Figure 2

Contact angle of a liquid lying on a surface and balance between surface tensions.

Figure 3

Schematic of droplet in (a) Wenzel state and (b) Cassie and Baxter state.

Figure 4

Schematic of advancing and receding angles of a droplet sliding on a surface. Contact angle hysteresis is defined as the difference between these two.

Figure 5

Schematic of a typical experimental setup for water dripping tests.

Figure 6

Schematic of the most common experimental methods for evaluating ice adhesion. (a) Peak force method. (b) Centrifugal force method. (c) Tensile force method. (Reprinted from [79], with permission from Elsevier). (d) Lateral view of the clamped ice-aluminum beam employed in the dynamic vibration test [80].

Figure 7

(a) SEM image of the laser processed surface by parallel scanning lines. Highlighted in red is an enlarged image of the cauliflower-like protrusions spread on the micro-gratings. (b) Delay times as a function of the pitch distance h (Adapted from [65], with permission from Elsevier).

Figure 8

(a) Scanning electron microscope images of the stainless steel laser textured samples. Groove pitches: 80, 140, and 240 μm. In the insets, magnifications of the redeposited aggregates. (b) Evolution of the droplet set on the original and laser-machined superhydrophobic surfaces at subzero temperature (−8.5 ± 0.5 °C) (Reprinted with permission from [109]).

Figure 9

Snapshots of water accumulation (a) on the pristine surface compared with (b) the laser-treated Al2024 one at −20 °C. (Reproduced from [111] under the Creative Commons Attribution License).

Figure 10

(a) Morphology of samples irradiated with laser fluences of 10 J cm⁻². (b) Freezing of the water droplet set on the superhydrophobic silicone rubber surface (laser fluences 12.5 J cm⁻²). In the red circle a bubble squeezed into the water droplet during the process is highlithed, Adapted from [115] (© IOP Publishing. Reproduced with permission. All rights reserved).

Figure 11

SEM image of laser fabricated hierarchical structures: matrix micropattern with a pitch distance of 50 μm covered by LIPSS (Reprinted from [120], with permission from Elsevier).

Figure 12

(a) Hierarchical microstructures, via DLW and DLIP techniques on pure aluminum. (b) Comparison between the contact angle of untreated reference, DLW, DLIP, and DLW + DLIP textured samples. The inserted images represent the droplets providing the measured angles depending on the temperature. (c) Average freezing time on an untreated reference, DLW, DLIP, and DLW + DLIP structures at −20 °C. The experiments were performed using 8 µL of deionized water (From [124] under http://creativecommons.org/licenses/by/4.0/).

Figure 13

Side view SEM image of two laser textured surfaces with a spatial period (a) bigger than and (b) comparable to a water droplet of 20 µm. (Reproduced from [124] under http://creativecommons.org/licenses/by/4.0/).