Controlling the Wetting Properties of Superhydrophobic Titanium Surface Fabricated by UV Nanosecond-Pulsed Laser and Heat Treatment

Abstract

In this study, the effects of nanosecond-pulsed laser and pattern design were researched on the wettability of titanium material. Nanosecond-pulsed laser and heat treatment are used to fabricate superhydrophobic titanium surfaces. The effects of laser power (1–3 W) and step size (50–300 µm) on a microscale patterned titanium surface (line pattern and grid pattern) were investigated to explain the relation between microstructure and superhydrophobicity. The surface morphologies and wettability of the surfaces were analyzed by three-dimensional confocal microscopy and a contact angle meter. The results show that the laser power and pattern design affected the apparent contact angle (CA) and sliding angle (SA). The maximum step size, which could show superhydrophobicity with apparent CA > 150° and SA < 10°, was increased when the laser power increased from 1 to 3 W. Grid pattern showed isotropic wetting behavior, but line pattern showed both isotropic and anisotropic wetting behavior according to step size and laser power. Furthermore, when choosing the proper laser power and step size, the wetting properties of superhydrophobic surface such as lotus effect (apparent CA > 150° and SA < 10°) and petal effect (apparent CA > 150° and no SA) and isotropic/anisotropic behavior can be controlled for applications of water droplet control.

Modulation and Control of Wettability and Hardness of Zr-Based Metallic Glass via Facile Laser Surface Texturing

“…A 2 h heat treatment ensured that both of the laser textured surfaces reached superhydrophobicity, with θ w values of 155.9 ± 1.2 • and 154.5 ± 1.9 • , respectively (Figure 6f,g). As discussed in the previous section, low-temperature heat treatment with an annealing temperature of ~150 • C has been proved to be an efficient approach to achieve wettability transition from superhydrophilicity to superhydrophobicity for various metallic materials such as aluminum, copper, stainless steel, and titanium [28][29][30][31][32][33][34][35][36]. However, this wetting state transition approach has never been utilized and confirmed for BMG.…”

“…As indicated in [50], as the electronic structure of metal oxide facilitates the formation of hydrogen bonds and increases the surface energy, the laser textured surface typically exhibited superhydrophobicity. For the laser textured surface with heat treatment, subtle increases in C and Si peaks can be detected, indicating that hydrophobic functional groups, including -CH 2 -, -CH 3 , C=C as well as thin PDMS layer, should have been absorbed and deposited onto the laser textured BMG surface, rendering the heat-treated surface with superhydrophobicity [33,49].…”

“…In recent years, laser-based surface texturing has been proved to be one of the most efficient techniques to modify and control important surface functionalities, including surface wettability [18][19][20][21][22], reflectivity [23,24], anti-icing property [25,26], corrosion resistance [27], etc. For example, wettability transition from superhydrophilicity to superhydrophobicity has been achieved on various materials including aluminum [28], copper [29], stainless steel [30,31], and titanium [32][33][34][35][36] by combining laser surface texturing and lowtemperature annealing. In terms of laser texturing for BMG materials, there have been some recent research efforts on modification of surface properties of BMG via creation of laser-induced surface texture and change of surface chemistry [15,16,[37][38][39][40][41][42].…”

Wetting angle stability of steel surface structures after laser treatment

“…Alternatively, lasers also allow controlling the surface wettability of various materials, in particular of metals. It is known that immediately after laser micro-structuring of metals their surface becomes hydrophilic (Kietzig, A.M. et al 2009;Ngo, C.V. et al 2018;Sciancalepore, C. et al 2018;Bizi-Bandoki, P. et al 2013;Kietziga, A. M. et al, 2011;Ngo, C. V. et al 2017). Authors (Kietzig, A.M. et al 2009;Sciancalepore, C. et al 2018;Bizi-Bandoki, P. et al 2013;Kietziga, A. M. et al, 2011) report that such surfaces acquire hydrophobic properties if structured materials are kept in ambient air.…”

“…To explain the wetting transition phenomena, different mechanisms were evoked. For example, several authors (Ngo, C.V. et al 2018;Ngo, C. V. et al 2017) proposed a method of accelerating the transition process by lowtemperature annealing, which also leads to the formation of hydrophobic surfaces.…”