Superhydrophobic Aluminum Surfaces Research Articles

Preparation of mechanically durable superhydrophobic aluminum surfaces by LST/MAO and chemical modification

In this paper, a superhydrophobic surface with mechanical durability was prepared on 6061 aluminum (Al) alloy by combining laser surface texturing (LST) and micro-arc oxidation (MAO) techniques followed by chemical immersion treatment. The effects of processing on Al alloys with different texturing spacings on the surface morphology, roughness, surface wettability, and corrosion resistance of the subsequently formed composite coatings were analyzed. The results show that a superhydrophobic surface was obtained with the water contract angle (WCA) of 158.3 ° and the roll-off angle of 9.5 ° at a texture spacing of 300 μm. This was due to the fact that the surface microroughness texturization process created by LST on the surface increased the generation of surface nanostructures, and combined with the natural nanostructure possessed by MAO, unique " double " nanostructure was formed on the surface. This surface structure increased the area of fluoride attachment, reduced the solid-liquid contact area, and decreased the adhesion of droplets to the surface, resulting in higher hydrophobicity. Electrochemical corrosion experiment showed that the corrosion current density of LM-300 was 2 orders of magnitude lower than that of the LM-0 sample, clearly demonstrating better corrosion resistance. In addition, the prepared superhydrophobic surface presented excellent mechanical durability, and in the ceramic zirconia cyclic abrasion experiment, the superhydrophobic surface was able to withstand 61 cycles of abrasion at a pressure of about 2.5 kPa.

Capacitive sensing of frost growth dynamics on aluminum surfaces with different wettabilities

Frost formation is a critical issue in many industries including air conditioning and refrigeration, aviation, transportation, and cryogenics. Frost buildup on heat exchanger surfaces reduces their efficiency by acting as a thermal resistance and by reducing or blocking the airflow. Defrosting is therefore necessary to maintain system efficiency. However, defrost initiation and cycle duration are critical parameters that govern system performance. Excessively early or late defrosting can result in energy loss. Frost detection is thus essential to carry out defrosting efficiently. To know when to initiate defrost, both the density and thickness of the frost must be known as both affect the frost thermal resistance. However, state of the art approaches are not sensitive to both frost density and thickness. Here, a capacitive sensing method is proposed that is sensitive to both the density and thickness of the frost. The method can achieve precise frost detection, offering insights into the ideal time to initiate defrosting by being sensitive to factors that affect frost specific thermal resistance. Experiments are carried out on plain (hydrophilic), superhydrophobic, and superhydrophilic aluminum surfaces at three different surface temperatures (−6 °C, −10 °C, −16 °C) to investigate the sensing performance. The capacitance measured increases with time as frost forms and grows. This change in capacitance, along with mass and thickness data, was used as a tool to characterize frost growth. The results indicate that decreasing wettability (superhydrophilic to plain (hydrophilic) to superhydrophobic) results in a decreasing trend in mass accumulation, frost density, and change in capacitance and an increasing trend in frost thicknesses and thermal resistance. It was also demonstrated that increasing surface temperature results in decreasing changes in capacitance (measurement sensitivity), mass accumulation, frost thicknesses, and thermal resistance, with an increasing trend in frost density. A strong correlation between frost mass and change in capacitance was observed regardless of surface temperature or wettability. This rendered implications for the best time of defrosting initiation. The proposed approach offers high accuracy, sensitivity, and convenience as a non-invasive method to study dynamic frost growth with insights into more optimal defrosting cycles, contributing to the development of more efficient energy systems.

Impact of gas bubbles on bacterial adhesion on super-hydrophobic aluminum surfaces

Super-hydrophobic surface (SHS), which traps micro/nano-scale gas bubbles on solid walls, has been reported to greatly reduce bacterial adhesion and biofouling. However, it is unclear whether and how the trapped gas bubbles reduce the bacterial adhesion. Here, we examine the role of the trapped gas on the bacterial adhesion by measuring the spatial distributions of attached bacteria on SHS using scanning electron microscopy (SEM). Two SHSs, one with regular micro-grooves, and the other with randomly roughed textures at micro/nano-scales, both created on aluminum substrates, were tested. We found that for a SHS where gas bubbles are trapped between roughness elements, bacteria only attach to the surface areas that are not covered by gas (e.g., top of roughness elements), while the areas covered by gas bubbles - gaps between roughness elements - are free of bacteria. In contrast, for a rough surface with the same texture geometry as that of SHS but no hydrophobic chemistry, bacteria are distributed evenly to the top and gap of roughness elements. Our results suggest that the SHS may reduce biofouling by providing a physical barrier of gas-liquid interface which separates bacteria from the solid walls. Furthermore, we showed that nano-scale roughness on SHS is insufficient to prevent bacterial adhesion. Our results should provide useful guidance for the future engineering design of efficient anti-biofouling materials.

A composite pore-structured superhydrophobic aluminum surface for durable anti-icing

The icing of overhead aluminum conductors is a serious threat to the safe operation of power systems. Various coatings for anti-icing have to face the challenge of durability. Superhydrophobic (SHP) coatings with self-healing properties are gradually showing good anti-icing durability. Herein, SHP self-healing surfaces with composite pore structures were successfully constructed on 1060 aluminum by two-step anodizing and infusion of triethoxy (1H,1H,2H, 2H-perfluoro-1-octyl)silane (POTS). A preparation process of composite pore structure consisting of upper layer of large pores and lower layer of small pores was designed and obtained via two-step anodizing. The impregnated POTS modified the composite pore structure to achieve superhydrophobicity while providing self-healing properties. The SHP surfaces with excellent performance were prepared by optimizing the appropriate current density and oxidation time. The contact and sliding angles were 166.5° and 0.5°, respectively. The frosting time was extended to 175 min, whereas the ice adhesion strength was lowered to 4.3 kPa. Additionally, the SHP surface with composite pore structure demonstrated superior durability and self-healing properties to single pore structure. The composite pore structure could maintain outstanding superhydrophobicity after 12 times of damage/self-healing compared to single pore structure (eight times). The SHP surface with composite pore structure successfully self-healed three times and withstood 135 icing/deicing cycles keeping the ice adhesion strength below 20 kPa, which is preferable to single pore structure (two times). The SHP self-healing aluminum surfaces developed in this work are highly promising for application and can promote the development of SHP coatings for anti-icing on power transmission lines.

Preparation of a Wear-Resistant, Superhydrophobic SiO2/Polymethyl Methacrylate Composite Coating on Aluminum Surface Processed with Nanosecond Laser.

Superhydrophobic coatings are limited by complex preparation processes and poor mechanical durability in practical applications. In this study, a mechanically robust superhydrophobic composite coating was applied to an aluminum surface that underwent processing with a nanosecond laser (referred to as a superhydrophobic aluminum surface). It exhibits a high water contact angle (WCA) of 158.81°, a low sliding angle (SA) of less than 5°, and excellent self-cleaning ability. The wear test shows its durability, and the corrosion test shows its excellent corrosion resistance. This study provides a framework for the preparation of robust superhydrophobic surfaces that may have potential applications in many fields.

Metal dopant infused superhydrophobic aluminum surface through sustainable processing

The present work proposes a simple, scalable, and economical route for producing superhydrophobic surfaces using thermomechanical and microwave-assisted hydrothermal treatments. Infusing dopants (Mg, Fe) during thermomechanical processing resulted in a distinct and denser nanostructures on aluminum surface. The silanization of these surfaces resulted in superhydrophobicity (θa > 160°) with low hysteresis (≈ 2°) and adhesion (≈ 25 µN) compared to un-doped surface. The reduction in pitch between nanostructures enhanced capillary pressure (> 900 kPa), stabilizing Cassie state and restricting three-phase line sagging. The present work highlights the importance of doping in enhancing the durability of nanostructures for improving de-wettability.

Superhydrophobic aluminum surfaces with nano-micro hierarchical composite structures: A novel and sustainable approach to corrosion protection

The unique properties of aluminum (Al) and its alloys make Al one of the most versatile, economical, and widely-used materials in various industries. However, the corrosion and leaching of Al can cause significant issues for the lifetimes of mechanical structures and machine components as well as environment and health problems. In the present study, a simple, eco-friendly, and rapid fabrication of superhydrophobic Al surfaces was introduced. The superhydrophobic Al surfaces with hierarchical composite structures combining microstructures prepared by laser texturing, the new formation of pseudo-boehmite nanostructures prepared by boiling water treatment, and low surface energy prepared by silicone oil heat treatment showed excellent corrosion resistance. The mechanism for wettability change and anti-corrosion were analyzed. The influence of laser parameters and surface modification procedures on the wettability and corrosion resistance of Al surfaces was also analyzed systematically through a series of surface characterization techniques, potentiodynamic polarization tests, and electrochemical impedance spectroscopy tests. The corrosion protection efficiency of the fabricated superhydrophobic Al surface has reached up to 99.40 % as compared with an untreated flat surface. Furthermore, the fabricated superhydrophobic surfaces show good stability even after prolonged exposure to air, fresh water, seawater, and high temperature environments. The performance of the non-wetting surfaces is demonstrated through self-cleaning, water jetting, and water droplet bouncing phenomena. This research provides a novel and sustainable approach for superhydrophobic metal surfaces and improved corrosion resistance for potential practical applications.

Condensation heat transfer between a vertical superhydrophobic aluminum surface and moist air under natural convection

Condensation heat transfer at superhydrophobic surfaces has raised a lot of interest due to their potential application in atmospheric water harvesting and air-conditioning. In moist air, the condensation heat transfer using a superhydrophobic surface can be negatively affected by the existence of a large amount of non-condensable gas, namely, the dry air. Besides, the air flow pattern would substantially affect the surface condensation rate due to the convective mass transfer of water vapor. In this study, the condensation regime of a superhydrophobic aluminum surface vertically positioned in quiescent moist air was visualized and the condensation rate was experimentally investigated. Condensation experiments were also performed by using hydrophobic, hydrophilic, and superhydrophilic surfaces for comparison. The condensation rate of the superhydrophobic surface was consistent with that of other surfaces, though the condensation regimes of the four surfaces were quite different. The average deviation between the experimental condensation rate and the empirical correlation of natural convection heat and mass transfer was within 12%. The result indicates that vapor transfer induced by diffusion and convection in the boundary layer rather than the heat transfer resistance associated with condensate dominates the condensation heat and mass transfer between the moist air and the superhydrophobic surface.

Robust, Superhydrophobic Aluminum Fins with Excellent Mechanical Durability and Self-Cleaning Ability

The self-cleaning ability of superhydrophobic metal surfaces has attracted extensive attention. The preparation of superhydrophobic material using the coating method is a common processing method. In this experiment, aluminum fins were processed by laser etching and perfluorinated two-step coating. The aluminum surface was modified using a femtosecond laser and 1H,1H,2H,2H- perfluorooctane triethoxysilane (PFOTES). A superhydrophobic aluminum surface with excellent mechanical stability and self-cleaning properties was obtained with the superhydrophobic contact angle (WCA) of 152.8° and the rolling angle (SA) of 0.6°. The results show that the superhydrophobic surface has an excellent cleaning effect compared with an ordinary surface in unit time. Then, a wear resistance test of the superhydrophobic surface was carried out by using the physical wear method. The results show that physical wear had a low influence on the hydrophobic property of the specimen surface. Finally, the Vickers hardness analysis found that the superhydrophobic surface hardness was significantly better than the ordinary surface hardness compared with the superhydrophobic surface hardness. Based on the excellent self-cleaning properties, wear resistance, and robustness of superhydrophobic materials, the laser-etched and perfluorinated superhydrophobic aluminum fins designed and manufactured in this study have broad application prospects in improving the heat transfer efficiency of finned heat exchangers.

Superhydrophobic and oleophobic microtextured aluminum surface with long durability under corrosive environment

Superhydrophobic (SHP) and oleophobic aluminum surfaces have been prepared through the combination of a scalable chemical microtexturing process and surface functionalization with long-chained polyfluoroalkyl moieties. The effect of an anodic layer on the microtextured surface has been assessed considering surface morphology, superhydrophobicity, surface mechanical properties and corrosion protection enhancement. The surface functionalization with polyfluoroalkyl moieties has been tackled in two different ways: (i) grafting of the polyfluoroalkyl moieties and (ii) deposition of a thin hybrid coating with low content of polyfluoroalkyl-containing compound. Aluminum surfaces showing high durability in salt spray environments, which maintain SHP and oleophobic properties at least up to 2016 h have been attained. Applications for this kind of surfaces range from easy-to-clean surfaces to anti-icing or anti-condensation functionalities that could be of interest for several sectors.

Hierarchical composite structure to simultaneously realize superior superhydrophobicity and anti-reflection

Superhydrophobicity and anti-reflection of metallic surfaces have potential applications, and obtaining superhydrophobicity on metallic surfaces by simple methods is still a challenge. The composite microstructure consisting of micro-protrusions, micro-lumps and particles was fabricated on aluminum surface by laser ablation. A layer of hydrophobic species that can prevent the surface from being wetted formed on the microstructure through organic adsorption. In particular, laser ablation parameters were optimized to achieve better superhydrophobicity and anti-reflection. The fabricated superhydrophobic surfaces showed contact angles > 165° for water and contact angles > 160° for high-concentration solutions and high-viscosity solutions. Conventional bounce contact time < 10 ms was exhibited for water droplets impacting on fabricated surfaces, especially, the shortest contact time reaching 9.4 ms. anti-reflection was also realized on the laser-ablated aluminum surface, and specular reflections were almost completely avoided by laser ablation structures. The mechanism of the transition from superhydrophilic to superhydrophobic on fabricated surfaces was discussed. Superhydrophobic aluminum surfaces with anti-reflection could be efficiently manufactured in a few hours without special equipment and harsh condition through the proposed two-step method.

Superhydrophobic and Self-Cleaning Aluminum via a Rapid and Controlled Process

Superhydrophobic and self-cleaning materials have been an extensive topic of research owing to their corrosion resistance, antifouling, and anti-icing properties. In the past, superhydrophobicity in aluminum has been obtained by a variety of techniques involving etching by sandblasting, chemical etching, boiling in water, etc. followed by treatment with a fluorochemical and organic solution. However, these techniques are not controlled, might not be easy to implement on a large scale, and mostly make use of fluorochemicals, which are risky for human health and the environment. Therefore, there is a need for a rapid and controlled fabrication process that can provide patterned superhydrophobicity without compromising the environment or the human health. Here, a rapid, controlled, and environmentally friendly procedure for fabricating a superhydrophobic and self-cleaning aluminum surface has been developed, achieving a contact angle of 158.06° and a sliding angle of 1.94°. In the two-step process, a rough surface was obtained using the laser etching technique in under 3 min, which resulted in a precisely controlled pattern with a dual-scale roughness on the surface (∼20–30 μm). Finally, a low surface energy was imparted to the surface by treatment with stearic acid where a low concentration of 2 × 10–4 M and no more than 10 s of exposure was found to be sufficient. Unlike various superficially coated materials, this superhydrophobic surface is durable and does not lose its properties after dipping in water for up to 4 days, encountering fine sand or mud, or at extreme surrounding temperatures of −18 to 100 °C. Thus, this rapid and controlled process for obtaining superhydrophobic aluminum potentially can be deployed for large-scale, structural applications.

Efficient fabrication of ternary coupling biomimetic superhydrophobic surfaces with superior performance of anti-wetting and self-cleaning by a simple two-step method

Efficiently obtaining ideal superhydrophobic metallic surfaces through traditional laser ablation is still a challenge. Meanwhile, revealing the mechanism of the transition from superhydrophilic to superhydrophobic of laser-ablated metallic surfaces is required. Inspired by the lotus leaf, we fabricated the arrays of micro-protrusions on aluminum substrates by nanosecond laser ablation. A layer of hydrophobic species was formed on the micro-protrusions after organic adsorption process, which promoted the surface to obtain superior superhydrophobic, anti-wetting and self-cleaning properties. The principle of the transition from superhydrophilic to superhydrophobic during heat treatment process was revealed, and how organic adsorption temperature and time affect water contact angle and slide angle was clarified. We found that nano-particles can drastically reduce the solid–liquid fraction of the surface after analysis. The parameters including laser scanning space, organic adsorption time and heat treatment temperature were optimized to realize high-efficient and energy-saving production. Furthermore, superior wetting resistance to various solutions and the self-cleaning property for solid powders were experimentally indicated. Superhydrophobic aluminum surfaces could be efficiently fabricated in several hours without any expensive equipment, complicated process, strict environment and environmentally harmful chemical reagent by the proposed two-step method.

Femtosecond laser fabrication and chemical coating of anti-corrosion ethylene-glycol repellent aluminum surfaces

Ethylene glycol (EG) is widely used as a cooling agent in factories, aviation, and automobiles. However, its corrosive nature can create significant damage and reduce the life cycle of devices. This paper compares three different methods to achieve the superhydrophobic anti-corrosion aluminum surfaces for working in an engine coolant environment. The methods are combinations between femtosecond laser fabrication and chemical coatings using Polydimethylsiloxane (PDMS) and Triethoxy-1H,1H,2H,2H-tridecafluoro-n-octylsilane (TTFOS). All the samples show superhydrophobicity with contact angles greater than 150°, and sliding angles smaller than 10°. The superhydrophobic surface (SHS) show the best corrosion rate up to three orders of magnitude compared to flat surfaces when working in an engine coolant environment. Moreover, corrosion inhibition efficiencies of the fabricated surfaces impress the best results greater than 98%. The anti-corrosion behavior of the SHS is explained. After comparing the performances of the surfaces fabricated by three methods, the most suitable method is proposed to produce anti-corrosion aluminum surfaces for applications using engine coolant as an environment.

Optimization of coating parameters for fabrication of robust superhydrophobic (SHP) aluminum and evaluation of corrosion performance in aggressive medium

The huge interest in superhydrophobic surfaces originates from their potential engineering applications in corrosion protection, antifouling, oil recovery, self-cleaning, anti-adhesion, anti-icing, medical dressing, drag reduction and radiative cooling. Despite the progress made in developing superhydrophobic (SHP) coatings, a key challenge is the ability to fabricate mechanically robust SHP surfaces and a proper understanding of the corrosion performance of SHP surfaces in aggressive conditions. Here, we report a simple, rapid, inexpensive, scalable and eco-friendly method for fabrication of mechanically durable superhydrophobic (SHP) aluminum surfaces with self-cleaning properties using a scalable dip-coating method. The coating parameters were optimized to obtain a robust coating with desirable properties such as water contact angle (WCA), sliding angle, self-cleaning, abrasion and corrosion resistance. To obtain good adhesion between the substrate and the coating, chemical etching and hydroxylation of the Al surface were used. At an optimal withdrawal speed of the substrate in the precursor solutions, a maximum WCA of 172.3° ± 1.1° (SA ~ 1° ± 1°) was achieved. The hierarchical micro-nano roughness and the presence of the Si-(CH3)3 group were responsible for the superhydrophobic behavior. The existence of a covalent bond between the Al surface and the middle connecting layer and –O-Si-CH3 groups on the surface of the SHP Al are confirmed by LRS and XPS, respectively. The electrochemical studies in 3.5 wt% NaCl solution show that the Rct value of SHP Al during the initial state was ~2 orders higher than that of the bare sample. The Cdl value of SHP Al was 6 orders less than that of bare after 1 h of exposure in chloride solution. On the SHP surface, a droplet with an impinging velocity of 0.36 m/s showed approximately 7 bounces. The superhydrophobicity of the SHP sample was preserved up to 150 cm abrasion distance. The hierarchical surface morphology and superhydrophobicity (WCA ~151°) were retained by the SHP samples even after 120 h of immersion in 3.5 wt% NaCl, which indicates its suitability in seawater applications such as ships, underwater instruments and pipelines and marine structures. Further, our work provides a framework to develop mechanically robust SHP coating for various applications.

Wettability tailored superhydrophobic and oil-infused slippery aluminium surface for improved anti-corrosion performance

Inspired by the non-contact nature offered by the superhydrophobic surfaces of living creatures in nature, the superhydrophobic and slippery liquid-infused porous surfaces (SLIPS) have been fabricated to meet the engineering problems including metal corrosion. In this research, we fabricate the hydrophobic, superhydrophobic, hydrophobic lubricant-infused surface (H-SLIPS), and superhydrophobic lubricant infused surface (SH-SLIPS) onto aluminium alloy surfaces and explored their anti-corrosion properties. The hydrophobic and superhydrophobic surfaces are fabricated by hot-water treatment and silicon oil grafting onto the plain and superhydrophilic surface created by hot water treatment of the chemically etched aluminium surface, respectively. The corresponding SLIPS are fabricated by infusion of the silicone oil onto the prepared hydrophobic and superhydrophobic surfaces. Although the superhydrophobic surface exhibits self-cleaning behavior, the SLIPS shows excellent self-healing properties. In addition, the H-SLIPS shows better lubricant layer stability compared to the SH-SLIPS. The corrosion resistive and electrochemical impedance studies illustrate that H-SLIPS surfaces exhibit excellent anti-corrosive properties as compared to other substrates and show long-term performance, even after 30 days. Thus, the study illustrates that H-SLIPS performs better and the infused oil stability is a critical factor for applications like anti-corrosion properties.

Enhancing the cooling capacity of radiant ceiling panels by latent heat transfer of superhydrophobic surfaces

The cooling capacity of a radiant ceiling panel (RCP) is highly limited in hot and humid climates as the panel surface temperature must be controlled higher than the air dew point to avoid condensation. Previous research suggested that condensation risks can be mitigated by using superhydrophobic surface materials, making ceiling panels applicable with the surface temperature below the air dew point. In this study, the enhanced cooling capacity of RCP due to latent heat transfer is estimated. Firstly, the condensation heat transfer of a superhydrophobic aluminum surface under natural convection in humid air with subcooling degrees between 3 °C and 12 °C was investigated by experiments. The data proved that the heat and mass transfer analogy method can be used to well predict the condensation heat transfer of the superhydrophobic surface with an error within 15%. Based on the finding, the heat and mass transfer analogy and traditional empirical methods were employed to predict the total heat flux of RCP with latent heat transfer. The results indicated an enhancement of 3% to 500% for the total heat flux compared with RCP with only sensible cooling, depending on the panel surface temperature, air temperature and humidity. This study draws a clear picture of how the cooling capacity of RCP can be enhanced via a latent heat transfer process, and this can be realized not necessarily with net moisture removal capacities with hydrophobic surfaces due to the droplet jumping phenomenon and the due re-evaporation process, showing a hidden potential of radiant cooling panels.

Study on Frost-Suppression Characteristics of Superhydrophobic Aluminum Surface Heat Exchanger Applied in Air Source Heat Pump

In order to solve the frosting problem of air source heat pump (ASHP) outdoor heat exchange under low-temperature and low-humidity conditions, a superhydrophobic aluminum (Al) surface with a contact angle (CA) of 158.3° was prepared by chemical etching. The microscopic characteristics of droplet condensation and the freezing process of a superhydrophobic surface were revealed through visual experiments and theoretical analysis. On this basis, the frost-suppression effect of a superhydrophobic Al-based surface simulating the distribution of actual heat exchanger fins was preliminarily explored. The results demonstrated that, due to the large nucleation energy barrier and the coalescence-bounce behavior of droplets, the condensed droplets on the superhydrophobic surface appeared late and their quantity was low. The thermal conductivity of the droplets on a superhydrophobic surface was large, so their freezing rate was low. The frosting amount on the superhydrophobic Al-based surface was 69.79% of that of the bare Al-based surface. In turn, the time required for melting the frost layer on the superhydrophobic Al-based surface was 64% of that on the bare Al-based surface. The results of this study lay an experimental and theoretical foundation for the application of superhydrophobic technology on the scale of heat exchangers.

Superhydrophobic Aluminium Surface to Enhance Corrosion Resistance and Obtain Self-Cleaning and Anti-Icing Ability.

A facile environmentally acceptable surface roughening method using chemical etching in HCl/H2O2 followed by grafting with n-octyltrimethoxysilane (AS-8) and 1H,1H,2H,2H-perfluorooctyltrimethoxysilane (FAS-8) was studied to fabricate a (super)hydrophobic aluminium surface. The ground aluminium surface after selected etching times (before and after grafting), was characterised using a contact profilometer, optical tensiometer, scanning electron microscope coupled with an energy-dispersive spectroscope and X-ray photoelectron spectroscope to evaluate surface roughness, wettability, surface morphology and composition. The durability of the grafted surface was tested using thermal and UV resistance tests. The corrosion properties were evaluated using potentiodynamic measurements and standard salts spray testing, ASTM B117-19. Finally, the self-cleaning and anti-icing abilities were assessed. The grafted aluminium surface with octyl- or perfluorooctyl silane reflected the highly hydrophobic (AS-8) and superhydrophobic behaviour (FAS-8). Moreover, the different behaviour of the octyl- or perfluorooctyl chain in the silane molecule on modified surface properties was also noticed because durability tests confirmed greater thermal, UV stability and corrosion resistance of FAS-8 compared to AS-8. The aluminium etched for 2 min and grafted with FAS-8 also demonstrated an excellent self-cleaning and anti-icing performance.

Rapid fabrication of near superhydrophobic aluminium surface through nanosecond laser texture and heat treatment

Controlling surface wettability inspired by nano structure of lotus leaf has attracted much attention. The superhydrophobicity on the metals is significant for the applications including water repellence, self-cleaning, anti-corrosion, and reduction of drag. Herein a near superhydrophobic surface of 5051 aluminium has been fabricated by employing a combination of nanosecond laser texture and heat treatment, without using any toxic chemicals. The aluminium surface was textured by fibre nanosecond laser and then heat treated at 150 °C to create the near superhydrophobic surface. The evolution of heat treatment time with respect to contact angle measurements has been investigated. The contact angle became 0° when processed by two different kinds of laser textures (sinusoid pattern and grid pattern). The influence of heat treatment on the wettability of the laser textured aluminium surface was studied. The contact angle exhibits 134.88° and 136.97° for sinusoidal pattern and grid pattern with 72 hours heat treatment, respectively. The mechanism for fast wettability conversion time is discussed. This method is a rapid and environment-friendly process, which is feasible for fabrication.