Anti-icing Applications Research Articles

Long-lasting low fluorinated stainless steel hierarchical surfaces for omniphobic, anti-fouling and anti-icing applications

Stainless steel (SS) alloys are prevalent in many industries, household appliances or other commodities, where a strict control of surface properties is required to tailor their interaction with the environment. In this work we report a new procedure of stainless steel surface processing that provides a multifunctional response including superhydrophobicity, omniphobicity, self-cleaning, anti-fouling and effective anti-icing capacity, while still preserving a corrosion resistance similar to that of this material in compact form. The method consists of a first nanostructuration step followed by a low fluorination. The nanostructured surfaces presented a dual scale roughness of hierarchical character. The liquid free approach developed in this work to get this singular surface nanostructuration entails a first laser treatment of stainless steel flat substrates, followed by the deposition of a nanostructured thin layer of this material by electron beam evaporation in an oblique angle configuration. The resulting hierarchical surfaces were subjected to fluorination by: (i) the plasma-assisted deposition of a thin Teflon-like coating or (ii) the grafting of fluorinated molecules. The self-cleanable, anti-adherent and ice repellent character of the resulting low fluorinated surfaces outperformed the behaviour of classical slippery surfaces obtained by the infusion of high amounts of fluorinated liquids. These hierarchical SS surfaces withstood mild abrasion tests and the effect of water jets. Moreover, the corrosion behaviour of the fluorinated surfaces determined through their potentiodynamic analysis revealed a similar corrosion resistance than the flat SS substrates. Outstandingly, after these corrosion tests, the fluorinated samples obtained by grafting preserved their surface functionalities without significant degradation. The high mechanical and chemical stability of these low fluorinated samples support their usage for a large variety of applications.

Anti-icing application of superhydrophobic coating on glass insulator

Insulators, as important components in transmission lines, are prone to disturb the safe running of the power system by the ice accumulation on surfaces. Traditional anti-icing coatings are difficult to practically apply to insulators. Here, superhydrophobic (SHP) coatings were fabricated on the glass insulator surface by spraying. We studied microstructure, wettability, water droplet bouncing behavior, and anti-glaze icing properties of SHP coating. The results demonstrated that SHP coatings had micro-nano rough structures. The excellent superhydrophobicity (contact angle of 165.2° and sliding angle of 3.7°) was achieved. The water droplet was easily adhered to the surface of the glass insulators. At the same time, individual water droplets could bounce away from the surface after impacting the SHP coating. In the glaze environment, water droplets sprayed onto the SHP coating merged with each other and slid off the surface. These significantly reduce the likelihood of freezing. Furthermore, the SHP coating could dramatically delay the glaze icing and decrease the icing area. The icing weight and icicle length were smaller than glass insulators. The SHP coatings prepared in this work display great potential for the anti-icing of glass insulators.

A novel superhydrophobic Al conductor with excellent anti-icing performance and its mechanism

Overhead conductor icing is one of the main factors causing transmission line failures. Superhydrophobic surface (SHS) with composite pore structure exhibits excellent anti-icing effectiveness and durability. Herein, this novel SHS was prepared on complex aluminum conductors by two-step anodic oxidation technology, and the motion behavior of droplets on the SHS conductor in the glaze icing environment was studied experimentally to analyze the anti-icing mechanism. The simulated glaze icing experiment results show that the SHS conductor significantly reduces the ice accumulation, and the icing weight is only 23 % of the untreated conductor. Compared with the flat surface, the groove structure of the SHS conductor enhances the ability of millimeter-sized droplets to bounce, and the contact time is less than 9 ms. Also, micron-sized spraying droplets exhibit excellent mobility on the SHS conductor surface, and the contact time is further reduced. Moreover, the SHS conductor has a good ability to delay the freezing of spraying droplets. The above factors endow the SHS conductor excellent anti-icing performance. This work lays a foundation for the anti-icing application of SHS on transmission lines.

Anti-icing properties and application of superhydrophobic coatings on asphalt pavement

In regions impacted by snow and ice, icy road surfaces can significantly reduce road capacity and endanger vehicle occupants. While traditional de-icing methods, such as spreading de-icing salt and mechanical de-icing, have drawbacks such as environmental pollution and damage to road facilities, superhydrophobic coating is gaining attention as a new, environmentally friendly, and efficient anti-icing method. Superhydrophobic coating can reduce the adhesion between the ice layer and the road surface, so as to achieve the purpose of road anti-icing in a low environmental impact way. To improve the anti-icing performance of asphalt pavement under low-temperature and humid conditions and reduce the impact of snow and ice freezing disaster, we prepared nano-SiO2 superhydrophobic coatings(SSC) and nano-SiO2/graphene composite superhydrophobic coatings(SGSC) using aqueous epoxy resins, hydrophobic nano-SiO2, and sparsely layered graphene as raw materials. The coatings' wettability, ice resistance, and road performance were analyzed. The study found that the contact angles of the SSC and SGSC were 151.2° and 153.0°, respectively. The BPN value of the SGSC decreased by 12.6% after application to the asphalt pavement, but it still meets safety requirements. The coating also maintains a certain degree of ice-resistant performance within five freeze-thaw cycles. The study results indicate that superhydrophobic coatings have the potential to improve pavement ice resistance.

Hydrophobic Surface Array Structure Based on Laser-Induced Graphene for Deicing and Anti-Icing Applications.

The exceptional performance of graphene has driven the advancement of its preparation techniques and applications. Laser-induced graphene (LIG), as a novel graphene preparation technique, has been applied in various fields. Graphene periodic structures created by the LIG technique exhibit superhydrophobic characteristics and can be used for deicing and anti-icing applications, which are significantly influenced by the laser parameters. The laser surface treatment process was simulated by a finite element software analysis (COMSOL Multiphysics) to optimize the scanning parameter range, and the linear array surface structure was subsequently fabricated by the LIG technique. The generation of graphene was confirmed by Raman spectroscopy and energy-dispersive X-ray spectroscopy. The periodic linear array structure was observed by scanning electron microscopy (SEM) and confocal laser imaging (CLSM). In addition, CLSM testings, contact angle measurements, and delayed icing experiments were systematically performed to investigate the effect of scanning speed on surface hydrophobicity. The results show that high-quality and uniform graphene can be achieved using the laser scanning speed of 125 mm/s. The periodic linear array structures can obviously increase the contact angle and suppress delayed icing. Furthermore, these structures have the enhanced ability of the electric heating deicing, which can reach 100 °C and 240 °C within 15 s and within 60 s under the DC voltage power supply ranging from 3 to 7 V, respectively. These results indicate that the LIG technique can be developed to provide an efficient, economical, and convenient approach for preparing graphene and that the hydrophobic surface array structure based on LIG has considerable potential for deicing and anti-icing applications.

Reversible thermochromic and heat storage coating for adaptive de/anti-icing and thermal regulation

In recent years, photothermal coatings have attracted researchers much attentions for anti-icing applications. However, the overheating due photothermal effect at midday or in non-icing period is inevitably encountered and results in the speed-up aging of the coatings. Herein, a reversible thermochromic phase-transition heat storage coating (TCHSC) containing thermochromic microcapsules is designed to adjust photothermal efficiency by discoloration during non-icing period. In cold surroundings, the coating surface shows black color and presents a high photothermal efficiency, which can transform solar energy into heat for anti-icing and de-icing effectively. Yet, the color of coating turns to white spontaneously in hot surroundings with a low photothermal generation efficiency, which avoids the overheating of coating. Besides, discoloration is caused by forming unconjuncted structure in thermochromic dye, and meanwhile the heat is stored during phase transition process of dye, which helps to adjust the temperature rising and cooling rate of coating and contributes to de/anti-icing. What’s more, discoloration temperature of thermochromic capsules can be tuned by adjusting the melting point of dye in thermochromic capsules. The TCHSC with heat regulation provides a new strategy to tackle the conventional overheating issue of photothermal anti-icing coating in summer or at midday, paving a key step towards its real applications.

Photo-thermal waxgels with fast wax layer regeneration ability for anti-icing.

Waxgels are known for their unique ability to generate sacrificial wax layers during anti-icing. To address the severe slow regrowth of the wax layer, here, carbon black is incorporated in the waxgel network to endow photothermal function. The rate of the regrowth of the wax layer is raised by >6 times under natural light conditions. Meanwhile, the photothermal waxgel showed improved anti-icing performances in terms of delayed ice formation and lower ice adhesion strength.

Facile one-step spraying preparation of fluorine-free transparent superhydrophobic composite coatings with tunable adhesion for self-cleaning and anti-icing applications

Transparent superhydrophobic coatings are of vital importance for various rising applications, such as photovoltaics, touch panels, smart windows, etc. However, their large-scale practical applications are severely restricted by hazardous fluorinated reagents, multistep preparation procedures, thermal treatment requirements, and poor durability. In this study, a facile one-step spraying method was proposed to fabricate transparent superhydrophobic coatings on various substrates, using an integrated fluorine-free suspension composed of siloxane-containing acrylate copolymers and SiO2 nanoparticles. Thanks to the incorporation of siloxane groups in the copolymers, the prepared coatings can be cured at room temperature without any thermal curing procedure. The resultant coatings exhibit excellent superhydrophobicity and high transparency, with a WCA of 162.2 ± 1.8° and ∼90.83 % transmittance at 550 nm, respectively. Besides, superhydrophobic surfaces with tunable water adhesion can be achieved by adjusting spray pressure. After a series of mechanical durability tests and chemical stability tests, the obtained coatings can still maintain their superhydrophobicity and high transparency. Moreover, the water freezing time on the coated glass can be extended and the ice adhesion strength was significantly reduced, exhibiting excellent anti-icing performance. The facile, fluorine-free, and one-step spraying coating method has scalability and universality, demonstrating the promising prospect of large-scale application in industry.

Effect of Asymmetry on the Contact Time of Droplet Impact on Superhydrophobic Cylindrical Surfaces.

Reducing the contact time during the droplet impact on the surface is crucial for anti-icing, self-cleaning, and heat transfer optimization applications. This study aims to minimize the contact time by modifying the surface curvature to create an asymmetric impact process. Our experiments showed that the increase in Weber numbers (We) and the decrease in the ratio of surface diameter to droplet diameter (D*) intensify the asymmetry of the impact process, yielding four distinct rebound modes. Low asymmetry observes the liquid retract toward the central point (Rebound Modes 1 and 2), whereas high asymmetry yields a wing-like rebound (Rebound Modes 3 and 4). In Rebound Mode 1, increased asymmetry would lead to more extended contact due to the prolonged waiting period. Conversely, the reduction in contact time in Rebound Mode 2 occurs due to increased asymmetry with no waiting period. For Rebound Modes 3 and 4, the retraction time could be divided into three stages, generated by two liquid detachment modes from the surface. Analysis reveals that an increased asymmetry would reduce the retraction time during the first stage but prolong it during the third stage, with no significant effects on the second. Four correlations, each pertaining to a distinct impact mode, are proposed based on these analyses to describe the contact time concerning We and D* for droplets impacting a superhydrophobic cylindrical surface.

Extending the modified steel slag cement into the hydrophobic and anti-icing application

Steel slag cement is commonly used as a non-load-bearing building material because of its low long-term strength. To promote its large-scale recycling, the new application of steel slag cement is significantly attractive. In this study, a new type of hydrophobic steel slag cement modified by Polydimethylsiloxane (PDMS) was prepared. α-C2S, β-C2S, C3A, C3S, C4AF, Aft, and CH were found in the samples by XRD. The Rietveld refinement technique was used to quantitatively analyze the content of hydration products. SEM and EDS analysis revealed the effect of PDMS and steel slag on the morphology of hydration products. The increase in the steel slag content, resulted in a smoother the surface due to the decrease in hydration products. It was found that PDMS covered the surface of hydration products, resulting in excellent hydrophobic properties. FTIR and XPS analysis showed that the main reason for the good hydrophobicity of the sample was that PDMS crosslinked on the surface of cement particles and filled the pores. With hydrophobic modification, the contact angle could reach 143.7°. The hydrophobically modified cement exhibited excellent self-cleaning ability, low water absorption, good photothermal properties, remarkable anti-icing properties, certain mechanical strength and high durability.

Does Anti-Condensation coatings guarantee Anti-Icing Properties?

To address the issues caused by ice accretion, researchers have made various attempts to obtain anti-icing surfaces, among which superhydrophobic surfaces have been approved to be an ideal candidate for anti-icing applications. Although extensive research has been conducted to date, the relationship between the anti-icing performance and the anti-condensation performance of superhydrophobic surfaces has yet to be investigated. In this study, superhydrophobic coatings with different surface microstructures were prepared. Tuning of surface morphology was conducted by controlling molar ratio of SiO2 nanoparticles and polyester powders. The superhydrophobic coatings with uniform surface microstructures exhibit anti-condensation performance. Superhydrophobic coatings with cavities-pore combined surface structures demonstrated superior anti-icing performance to other coatings. The relationship between the anti-icing and anti-condensation performance was investigated. It is verified that the anti-condensation performance of the superhydrophobic surface do not have a simple correlation with the anti-icing performance. Furthermore, the coatings present oil repellency, durable superhydrophobicity and anti-fouling properties.

Efficient Photothermal Anti-/Deicing Enabled by 3D Cu2-x S Encapsulated Phase Change Materials Mixed Superhydrophobic Coatings.

Photothermal superhydrophobic surfaces are one of the most promising anti-/deicing materials, yet they are limited by the low energy density and intermittent nature of solar energy. Here, a coupling solution based on microencapsulated phase change materials (MPCMs) that integrates photothermal effect and phase change thermal storage is proposed. Dual-shell octahedral MPCMs with Cu2 O as the first layer and 3D Cu2-x S as the second layer for the first time is designed. By morphology and phase manipulation of the Cu2-x S shell, the local surface plasmonic heating modulation of MPCMs is realized, and the MPCM reveals full-spectrum high absorption with a photothermal conversion efficiency up to 96.1%. The phase change temperature and enthalpy remain in good consistency after 200 cycles. Multifunctional photothermal phase-change superhydrophobic composite coatings are fabricated by combining the hydrolyzed and polycondensation products of octadecyl trichlorosilane and the dual-shell MPCM. The multifunctional coatings exhibit excellent anti-/deicing performance under low temperature and high humidity conditions. This work not only provides a new approach for the design of high-performance MPCMs but also opens up an avenue for the anti-icing application of photothermal phase-change superhydrophobic composite coatings.

A Sustainable Superhydrophobic and Photothermal Coatings for Anti-Icing Application on Concrete with a Simple Method for CNTs/SiO2 Modification

Ice formation on concrete surfaces significantly challenges productivity, economic growth, and safety in diverse industrial sectors. Superhydrophobic coatings represent an effective solution to delay ice formation, although their functionality deteriorates under repeated freeze–thaw cycles. To address this issue, carbon nanotubes (CNTs) are frequently employed due to their exceptional photothermal conversion and mechanical properties, which contribute to extending the sustainability of the superhydrophobic coatings. However, the chemical inertness of CNTs often necessitates complex reactions to modify their functionalization. In this study, we have invented a simple method involving the sequential growth of silica on the surface of CNTs and the hydrophobic modification of the silica surface to enhance CNT functionality. These CNTs/SiO2 functionalized nanoparticles were then incorporated into an epoxy resin using a simple spray technique, resulting in a superhydrophobic and photothermal coating on concrete. To fine-tune the coating’s properties, we explored the effects of varying the doping levels of the nanoparticles on the surface morphology, roughness, and wettability of the CNT/SiO2-EP coatings. The optimal level of hydrophobicity was achieved by doping the coatings with 300 mg of functionalized nanoparticles, yielding an impressive contact angle of 159.6°. The integration of functionalized nanoparticles into the epoxy matrix not only enhances hydrophobicity but also improves mechanical robustness and abrasion resistance by creating multiscale surface roughness. Additionally, the coating exhibits outstanding chemical stability even under extreme conditions. One of the most significant advantages of these coatings is their ability to extend the ice nucleation time significantly. This effect is primarily attributed to the superior superhydrophobicity of the nanoparticles and the remarkable photothermal conversion capability of the CNTs. Upon exposure to Xenon lamp radiation, the ice droplets rapidly melt, underscoring the impressive performance of these coatings in preventing ice formation.

A photothermal superhydrophobic coating with un-fluorinated modified CNTs for anti-icing applications on concrete

The problem of easy icing and difficult anti-icing on concrete pavement has prompted using superhydrophobic coatings as a potential solution. However, the coatings are prone to wetting failure after repeated icing-deicing cycles. In this study, a superhydrophobic and photothermal coating consisting of unfluorinated modified-carbon nanotubes (M-CNTs) and commercial epoxy is constructed by a simple spray process on concrete for anti-icing. Incorporating M-CNTs imparts the coating with exceptional superhydrophobic and photothermal characteristics, endowing the coating surface with excellent deicing under sunlight irradiation. The contact angle of the coating reaches 151° at −10 °C, and the freezing time extends from 55 s to 680 s. Under one sunlight intensity, the coating temperature rapidly increases from −10 ℃ to 81 ℃, and the ice changes from solid to liquid. It effectively acts as a barrier between water and the concrete surface, making it highly suitable and valuable in practical applications.

Investigation on Superhydrophobic and Icephobic Coatings For Anti-icing in Aircraft

In-flight ice accumulation on aircraft surfaces is a major concern from safety point of view. Many techniques have been used for decades but finding a low-cost approach without loss of power has attained more focus in recent years. This paper presents the investigation outcomes of superhydrophobic and iccephobic coatings for the anti-icing application. A specimen of 6061 Aluminum Alloy with PTFE coating is analyzed using the Ansys FENSAP-ICE simulation tool and subsequently was subjected to contact angle test. The PTFE coating shows excellent superhydrophobic nature and can serve the aircraft anti-icing requirements at low cost.

Drop Impact on Submillimeter-Structured Surfaces with Different Wetting Behaviors.

Droplet impact behaviors are crucial in controlling infectious diseases, inkjet printing, and anti-icing applications. The wettability and microstructure of the material surface are critical factors in this regard. Compared to microstructures, submillimeter structures are more damage-resistant, thereby ensuring droplet impact behaviors' stability. Herein, submillimeter-structured PDMS surfaces with varying wetting properties were prepared to investigate droplet impact behaviors. Experimental results indicate that submillimeter-structured surfaces are more prone to droplet splashing than flat surfaces, which can be suppressed by increasing surface hydrophilicity. An increase in the submillimeter pillar height and a decrease in spacing result in an increased critical Weber number. Additionally, the capillary forces of the superhydrophilic surface lead to droplet impact, accompanied by deposition. This study supports the long-term stable use of the droplet impact effect to achieve fluid separation.

Innovative Solid Slippery Coating: Uniting Mechanical Durability, Optical Transparency, Anti-Icing, and Anti-Graffiti Traits.

Slippery coatings, such as the slippery liquid-infused porous surface (SLIPS), have gained significant attention for their potential applications in anti-icing and anti-fouling. However, they lack durability when subjected to mechanical impact. In this study, we have developed a robust slippery coating by blending polyurethane acrylate (PUA) with methyltriethoxysilane (MTES) and perfluoropolyether (PFPE) in the solvent of butyl acetate. The resulting mixture is homogeneous and allows for uniform coating on various substrates using a drop coating process followed by drying at 160 °C for 3 h. The cured coating exhibits excellent water repellency (contact angle of ~108° and sliding angle of ~8°), high transparency (average visible transmittance of ~90%), exceptional adherence to the substrate (5B rating according to ASTMD 3359), and remarkable hardness (4H on the pencil hardness scale). Moreover, the coating is quite flexible and can be folded without affecting its wettability. The robustness of the coating is evident in its ability to maintain a sliding angle below 25° even when subjected to abrasion, water jetting, high temperature, and UV irradiation. Due to its excellent nonwetting properties, the coating can be employed in anti-icing, anti-graffiti, and anti-sticking applications. It effectively reduces ice adhesion on aluminum substrates from approximately 217 kPa to 12 kPa. Even after 20 cycles of icing and de-icing, there is only a slight increase in ice adhesion, stabilizing at 40 kPa. The coating can resist graffiti for up to 400 cycles of writing with an oily marker pen and erasing with a tissue. Additionally, the coating allows for easy removal of 3M tape thereon without leaving any residue.

In-depth analysis of the effect of physicochemical properties of ionic liquids on anti-icing behavior of silicon based-coatings

This study dissects the use of room temperature ionic liquids (RT-ILs) in a dynamic surface for anti-icing applications. Anti-icing properties of ILs-containing PDMS-based coatings fabricated by two different types of ILs, are evaluated to establish a relationship between the anti-icing behavior and physicochemical properties of the ILs. The surface chemistry of coatings and the existence of distinctive groups of the ILs anions on the surface of coatings characterized by Attenuated Total Reflectance-Fourier transform infrared (FTIR) spectroscopy (ATR-FTIR) and confirmed by using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy-energy dispersive X-ray analysis (SEM/EDX). The 3D profiles and roughness parameter of the surfaces were investigated by a confocal laser microscopy profiler. Regarding the importance of correlation between wettability and ice adhesion, the wettability of coatings was studied. The results show a significant reduction 30–40% in sliding angle (SA) and contact angle hysteresis (CAH) in ILs-containing coatings. Differential scanning calorimetry (DSC), freezing delay time, push-off and centrifugal adhesion tests (CAT) served to distinguish the performance of the two ILs in regard to ice nucleation temperature and formation time, and ice adhesion strength, respectively. The 60–70% reduction in ice adhesion strength for the IL-containing coatings, obtained by push-off test, is due to the presence of strong ionic hydrogen bounded water and the formation of self-lubricating quasi liquid layer that can function at much lower temperature. Solid-state nuclear magnetic resonance (NMR) spectroscopy has confirmed the presence of nonfrozen water molecules at the interface. Consequently, incorporating ILs into coatings provides an effective approach to delay ice nucleation, restrict ice growth recrystallization and reduce ice adhesion strength. A comparison of enhanced anti-icing performance of ILs-containing coatings highlights the significant influence of minor changes in the chemical structure of ILs on their potential for anti-icing applications.

Large-scale fabrication of superhydrophobic shape memory composite films for efficient anti-icing and de-icing

Ice and snow accretion on outdoor facilities may degrade their functions and reduce their service life. Superwetting materials have been widely studied and present high potential in anti-icing and de-icing applications. However, it remains challenging that the materials cannot prevent and remove the ice accretion spontaneously in harsh conditions. Penguins can freely jump in and out of extremely cold water (−40 °C) without forming macroscopic ice because of the superhydrophobic performance of their flexible feathers. Here, Penguins-inspired superhydrophobic shape memory composite films with unique properties, including lightweight and shape morphing, are fabricated via a two-step method consisting of spraying and peeling processes. It presents good superhydrophobic performance with a large WCA of 152.4 ± 5° and a small WSA of 6 ± 1° in addition to excellent shape memory performance (recovery ratio > 99%) and good mechanical strength. The simple fabrication methods make it possible to produce large-size films at low cost, which is versatile for different applications. Most importantly, the film displays the capabilities of inhibiting freezing, ice, and snow accumulation with improved ice removal efficiency due to the synergetic effects of the superhydrophobic and efficient photothermal activity. Furthermore, its robustness and durability make it a good candidate for industrial applications.

Thermohydraulic performance assessment of new alternative methods for anti-icing application against current application in an aircraft

In this study, anti-icing problems, which are mostly industrial problems in aerospace companies, have been numerically investigated. Herein, to enhance anti-icing performance of NACA0015, different jet-to-surface distances ( H/d), jet angles ( α), and slot jet designs with different aspect ratios ( ARs) have also been investigated. ANSYS Fluent 2020R2 commercial program has been utilized for all numerical calculations. In addition, the SST k-ω with low-Re correction wall treatment turbulence model has been used for solving turbulence equation. Furthermore, the average Nusselt number ( Nu) on the NACA0015's surface, pressure drop, and performance evaluation criteria (PEC) which define the anti-icing performance of novel proposed system have been presented section by section. As a result of the investigation, it has been obtained that the use of AR = 4 increases the Nu by 85.52% compared to circular jet for the H/d = 4 at α = 90°. The pressure drop value dramatically increases using AR = 4 around 307.85% compared to circular jet for H/d = 4 at α = 90°. Despite this drastic increment in pressure drop, the PEC value is kept as 1.14 using AR = 4, H/d = 4, and α = 90°. Finally, empirical correlations developed from existing findings have been presented with an error rate of lower than 5%.