Durable Coatings Research Articles

Dynamic covalent bonds enabled robust and self-healing superhydrophobic coatings with multifunctions

Inspired by plants and animals in nature, durable superhydrophobic surfaces have been successfully developed in the past decades. However, the practical application of these superhydrophobic surfaces suffers from poor mechanical and chemical stability after damage or longtime usage. Thus, effective silicone-based polymers are developed to prepare the intelligent self-healing and durable superhydrophobic coatings with multifunctions. The superhydrophobic coatings are composed of dynamic silicone polymers and silica nanoparticles, which can be applicable in various substrates with enhanced water repellency. The abundant hydrogen bonds and reversible B-O covalent bonds in the dynamic silicone polymers enable a strong binding force with the substrate and self-healing nature. Thus, the superhydrophobic coatings exhibit a high contact angle up to 159.3°, and a low sliding angle of 6.9°. Meanwhile, it displays mechanical stability against washing and abrasion damage, and chemical stability in acid and alkaline environment. Especially, it is capable of repairing the superhydrophobicity after damage due to the reversible association/dissociation of dynamic B-O covalent bonds in silicone polymers. In addition, the superhydrophobic cotton fabric shows excellent anti-fouling, self-cleaning, antibacterial property, and can be applied in oil–water separation with high efficiency. This robust and versatile superhydrophobic coatings without containing perfluoro-compounds are promising in commercial textile fishing treatment with low cost.

Synthesis and Properties of a Shape Memory–Assisted Self‐Healing Supramolecular Polyurethane Coating Based on Quadrupole Hydrogen Bonding

ABSTRACTIn this research, the synthesis and characterization of a shape memory–assisted self‐healing polyurethane (SHSMPU) coating based on strong quadrupole hydrogen bonding interaction have been investigated. The coating was fabricated with an acrylic polyol, an isocyanate functionalized ureidopyrimidinone (UPy‐NCO) as a hydrogen bonding provider, and methylene diphenyl diisocyanate (MDI) as chain extender. Fourier‐transform infrared spectroscopy (FT‐IR) confirmed that by incorporating the UPy‐NCO dimer in the polyurethane (PU) structure, strong hydrogen bonding appears, which can provide the healing function of the polymer. In addition, differential scanning calorimetry (DSC) showed that by increasing the UPy‐NCO amount, the overall Tg decreased and the material becomes more flexible. A rheometric investigation revealed that a sample containing 45% of UPy‐NCO as total diisocyanate shows good shape recovery and an healing efficiency of macroscale cracks of around 94.2%, which is much higher than the corresponding sample without UPy‐NCO (50.4%). Even better performances were obtained with microcracks, where tested samples were significantly healed at around 80°C in 10 min. Furthermore, the introduction of polyethylene glycol 400 (PEG400) into the polymer's backbone led to a reduced Tg and thus higher flexibility at room temperature. The combination of the observed properties makes these materials promising for application as durable and flexible polyurethane coatings.

Influence of Mechanical Activation on the Evolution of TiSiCN Powders for Reactive Plasma Spraying

In modern materials science and surface engineering, reactive plasma spraying (RPS) holds a key position due to its ability to create high-quality coatings with unique properties. The effectiveness of this process is largely determined by the physicochemical characteristics of the initial powder materials. This study examines the effects of mechanical activation for two compositions in the TiSiCN system and their impact on the quality and performance characteristics of RPS-produced coatings. It is shown that mechanical activation induces significant changes in the crystalline structure of the powders, reducing their particle size and increasing their specific surface area, thereby enhancing the reactivity of the materials during mechanochemical reactions. These changes contribute to the formation of dense and durable coatings with improved hardness and thermal stability. Thermogravimetric analysis (TGA) results confirm that the powders retain stable thermal properties and exhibit resistance to oxidation and decomposition. X-ray structural analysis reveals multiphase structures, including TiC, SiC, and TiCN, with the TiCN phase playing a key role in ensuring coating hardness. Additionally, SEM analysis showed that the TiSiCN-2-2 coating possesses a denser and more homogeneous structure with minimal pores and microcracks, providing superior mechanical strength and wear resistance compared to TiSiCN-1-2. Cross-sectional micrographs further revealed that the TiCN + Si coating has a greater average thickness (39.87 μm) and more uniform distribution compared to Ti + SiC (35.48 μm), indicating better application control and a more homogeneous material structure. Mechanical activation significantly influences the properties of powders, allowing for the determination of optimal parameters for RPS, which is a highly efficient method for creating coatings with unique performance characteristics.

Extending interfacial toughness and thermal cycling lifetime of thermal barrier coatings via interfacial 3D pattern

AbstractWeak interface bonding is a critical factor that compromises the long‐term durability of the thermal barrier coatings. To mitigate this, we introduce an innovative interface‐strengthening approach by integrating four types of 3D patterns at the top coat/bond coat interface using the laser cladding technique. Tensile tests demonstrate a significant enhancement in interfacial bonding strength, increasing by over 139.2% from 21.6 ± 1.7 MPa for conventional thermal barrier coatings without patterns to 51.67 MPa for the patterned coatings. Moreover, the thermal cycling lifetime has been extended by 41%, from 1026 ± 25 cycles for the conventional coating to 1936 ± 164 cycles for the patterned coating. This enhancement in interfacial toughness and thermal cycling lifetime is primarily because of the blocking and deflection effects of 3D patterns on interfacial crack propagation. Besides, the geometric parameters of the patterns play a crucial role in determining the failure behavior of the thermal barrier coatings. This strategy presents a practical solution for the development of durable thermal barrier coatings and provides the valuable insights for the optimization of other heterogeneous interfaces.

A surfactant-mediated dynamic protection strategy for 100% waterborne fabrication of durable superhydrophobic coatings

Waterborne preparation of superhydrophobic coatings now becomes strongly favored because of its environmental and health friendliness. However, the huge surface energy difference between low surface-energy components and water still poses a challenge for achieving their co-dispersion. Here, a surfactant-mediated protection strategy is proposed to achieve well dispersion of both SiO2 nanoparticles and perfluorosilane in water as well as block their conjugation, thereby fabricating a 100% waterborne F-FC-SiO2 suspension with high homogeneity and dispersion stability. During the painting and drying process, demulsification spontaneously triggers the deprotection and enables sufficient covalent conjugation between perfluorosilane and SiO2, thus achieving a superhydrophobic coating. This supramolecular protection/deprotection approach enables high compatibility of the F-FC-SiO2 suspension with versatile waterborne polymer emulsions (e.g., waterborne polyurethane, waterborne polysiloxane, and waterborne epoxy resin) to fabricate durable superhydrophobic coatings. The resulting composite coating can impart super-repellency to various substrates against aqueous solutions and multiple oils, displaying high antifouling and self-cleaning properties, as well as resistance to extreme mechanical abrasion and weathering. This work provides a promising approach for the convenient production of totally waterborne superhydrophobic coatings.

Reinforcing polyvinyl alcohol films with layered double hydroxide and tannic acid to enhance tensile strength, tribological performance, and corrosion resistance in biomedical coating applications

Abstract This study investigates the synergistic effects of incorporating layered double hydroxide (LDH) and tannic acid (TA) into polyvinyl alcohol (PVA) films to enhance their mechanical, tribological, and corrosion resistance properties for biomedical applications. Composite coating films were prepared by blending PVA with LDH and TA in various concentrations. The addition of LDH and TA significantly increased the crystallinity index of the composite films, with the highest crystallinity observed at 66.3% for the sample containing 1 wt% TA and 2 wt% LDH (PVA/TA1/LDH2). This enhancement in crystallinity contributed to improved mechanical performance, as demonstrated by tensile tests, where the PVA/TA1/LDH2 composite exhibited the highest tensile strength among all samples. Tribological testing revealed that the PVA/TA1/LDH2 composite also achieved the lowest coefficient of friction (COF), along with a minimal wear rate, indicating superior wear resistance. SEM analysis of the wear scars confirmed a narrow wear track and smoother surface morphology for this composite, which suggests effective load distribution and reduced surface degradation. The addition of TA was further shown to improve the corrosion resistance of the PVA composite films, with the PVA/TA1/LDH1 sample exhibiting the lowest corrosion current density (Icorr) of 0.36 μA cm−2, representing a significant improvement over neat PVA. These findings highlight the potential of PVA/LDH/TA films for coating applications in biomedical devices, where enhanced mechanical strength, wear resistance, and corrosion protection are critical. The synergistic effects of LDH and TA provide a pathway for developing durable and functional coatings, expanding the practical utility of PVA films in demanding biomedical environments.

Achieving durable double-layered thermal barrier coatings by tailoring multi-scale structures

Achieving durable double-layered thermal barrier coatings by tailoring multi-scale structures

Highly Active and Durable Nanostructured Nickel-Molybdenum Coatings as Hydrogen Electrocatalysts via Solution Precursor Plasma Spraying.

The increasing demand for green hydrogen is driving the development of efficient and durable electrocatalysts for the hydrogen evolution reaction (HER). Nickel-molybdenum (NiMo) alloys are among the best HER electrocatalysts in alkaline electrolytes, and here we report a scalable solution precursor plasma spraying (SPPS) process to produce the highly active Ni4Mo electrocatalysts directly onto metallic substrates. The NiMo coating coated onto inexpensive Ni mesh revealed an excellent HER performance with an overpotential of only 26 mV at -10 mA cm-2 with a Tafel slope of 55 mV dec-1. Excellent operational stability with minimum changes in overpotential were also observed even after extensive 60 hour high-current stability test. In addition, we investigate the influence of different substrates over the catalytic performance and operational stability. We also proposed that a slow, but consistent, dissolution of Mo is the primary degradation mechanism of NiMo-based coatings. This unique SPPS approach enables the scalable production of exceptional NiMo electrocatalysts with remarkable activity and durability, positioning them as ideal cathode materials for practical applications in alkaline water electrolysers.

Construction of Durable, Colored, Superhydrophobic Wood-Based Surface Coatings Using the Sand-In Method.

Highly durable color superhydrophobic coatings have attracted much attention in indoor and outdoor decorative applications. In this paper, colorful superhydrophobic coatings with excellent durability were prepared using silane coupling agent-modified iron oxide as the pigment and polydimethylsiloxane-compounded epoxy resin as the base material by the three-step method of "spraying-sanding-spraying". The method is low cost, has a simple preparation process, enables large-area preparation, and has a restorative function. The use of red, yellow, blue, and green four kinds of modified iron oxides through the single color or multicolor into the sand can be obtained by a variety of color coatings, and silica mixed with a variety of colors can be obtained from light to dark coatings. The coating has excellent superhydrophobicity and self-cleaning ability to withstand sandpaper abrasion, water impact, sand impact, UV exposure, and environmental testing. The coating is suitable for interior and exterior decoration and for protection of wooden buildings.

Durable Superhydrophobic Coatings with Attapulgite for Inhibiting 5G Radome Rain Attenuation.

5G radomes are easily wetted and stained by rainfall, which greatly reduces the quality of signal transmission. Superhydrophobic coatings are expected to solve this problem because of their unique wettability, but it is still challenging to develop robust superhydrophobic coatings via simple methods. Here, we report the design of robust superhydrophobic coatings containing oxalic acid-modified attapulgite (MDP) for inhibiting rain attenuation of 5G radomes. First, a homogeneous suspension was prepared by nonsolvent-induced phase separation of a silicone-modified polyester adhesive (SMPA) solution containing fluorinated MDP (F-MDP) nanorods. Superhydrophobic coatings can be easily prepared by spraying the suspension. The effects of phase separation and the SMPA/F-MDP ratio on the surface morphology, superhydrophobicity, and stability of the coatings were systematically investigated. The micro-/nanostructure and low surface energy endow the coatings with excellent static and dynamic superhydrophobicity. Compared with previous studies, the coatings exhibit excellent mechanical stability, flexibility, chemical stability, and pressure resistance due to the combined effects of adhesion by SMPA, self-similar micro-/nanostructures, reinforcement by the MDP nanorods, etc. Consequently, the coatings show good performance in preventing rain attenuation of 5G radomes, an emerging application of Superhydrophobic coatings. We believe that the coatings have great application potential in various fields, including 5G communication.

Robust photothermal anti/de-icing hydrophobic coating based on polydopamine (PDA) composition

The hydrophobic soft coating has low ice adhesion strength and hydrophobic stability in low-temperature and high-humidity environments, which is crucial for preventing ice formation on infrastructure and transportation systems. However, creating mechanically durable hydrophobic soft coatings using simple methods remains challenging. In this study, a high-hardness particle-toughened, self-stratifying organic layer with high photothermal conversion rate was developed to enhance coating durability and ice-repellent performance. By optimizing the ratio of dopamine (DA) and sodium alginate (SA), a hydrophobic photothermal agent (DPSn) with high hardness and a significant light-heat effect was synthesized. A durable, hydrophobic photothermal anti-ice coating (AR/20 %PDMS/x%DPS1) with varying DPS1 amounts was successfully created using a straightforward one-step spray method, utilizing the self-stratification characteristics of acrylic resin (AR) and polydimethylsiloxane (PDMS), along with the toughening effect of DPSn. The fiber cross-linked structure of DPS1 achieved a photothermal conversion rate of 87.5 %. Adding 4 wt% DPS1 increased the surface temperature of the AR/20 %PDMS coating to 96.5 ± 2.4 °C and boosted the coating’s adhesion strength from 6.70 ± 0.3 MPa to 7.23 ± 0.7 MPa. The AR/20 %PDMS/4%DPS1 coating demonstrated excellent anti-/de-icing performance after 60 friction cycles, 60 icing/de-icing cycles, and 132 h of acid-base immersion. Its simple preparation process and durable ice-repellent properties make it highly suitable for practical applications in photothermal hydrophobic soft coatings.

Preparation of Pressure-Resistant and Mechanically Durable Superhydrophobic Coatings via Non-Solvent Induced Phase Separation for Anti-Icing.

Inspired by the lotus leaf effect, superhydrophobic coatings have significant potential in various fields, However, their poor pressure resistance, weak mechanical durability, and complex preparation processes severely limit practical applications. Here, a method for preparing pressure-resistant and durable superhydrophobic coatings by simply spray-coating a phase separation suspension containing fluorinated silica nanoparticles and polyolefin adhesive onto substrates is introduced, which forms superhydrophobic coatings with a porous and hierarchical micro-/nanostructure. The resulting superhydrophobic coatings exhibit outstanding pressure resistance, maintaining a Cassie-Baxte state after 18 days of submersion in 1 m of water. Furthermore, the coatings demonstrate remarkable mechanical durability, withstanding 200 cycles of Taber abrasion, 100 cycles of tape-peeling, and 750g of sand abrasion. The coatings also show excellent chemical stability, enduring long-term immersion in corrosive liquids and 120 d of outdoor exposure. Additionally, the coatings display excellent anti-icing properties and can be applied to various substrate surfaces. This approach improves on the limitations of conventional superhydrophobic coatings and accelerates the application of superhydrophobic coatings in real-world environments.

Latex-Bridged Inverse Pickering Emulsion for Durable Superhydrophobic Coatings with Dual Antibacterial Activity.

There is agreement that every colloidal structure produces its own set of unique characteristics, properties, and applications. A colloidal phenomenon of latex-bridged water in a dimethyl carbonate (DMC) Pickering emulsion stabilized by R202 hydrophobic silica was investigated for its ability to act as a superhydrophobic coating (SHC) for cellulose substrates. First, various emulsion compositions were screened for their stability and droplet size. The final composition was then cross-examined by cryogenic scanning electron microscopy and optical and fluorescent microscopy to verify the colloidal structure. The drying pattern of the coating was investigated by using labeled samples under a fluorescent microscope and by scanning electron microscopy on a paper substrate. After the final ∼3 μm of dry coating was applied, it exhibited superhydrophobicity (advancing contact angle = 155°) and full functionality after 5 min at room temperature (RT). Coated samples maintained superhydrophobicity after 20 abrasion cycles and mechanical integrity after 50 s of water immersion. The SHC-coated paper demonstrated compatibility with a standard laser printer, and the coated paper demonstrated superhydrophobicity after printing. Finally, a propolis/DMC extract was produced and then analyzed by gas chromatography-mass spectroscopy (GC-MS) and infused into the SHC (PSHC). The newly formed PSHC demonstrated its ability to act effectively against E. coli biofilm and S. aureus planktonic cells and reduce their viability by over 90% and 99.99%, respectively.

PROSPECTS FOR THE USE OF MICROARC OXIDATION IN THE PRODUCTION OF AVIATION AND AUTOMOTIVE COMPONENTS

This article discusses the prospects for the application of microarc oxidation (MAO) technology in the aviation and automotive industries. The MAO process allows the creation of durable, wear-resistant and corrosion-resistant coatings on the surface of metal parts, which significantly increases their durability and performance characteristics. Technological aspects of MAO are discussed, including surface preparation features, selection of electrolytes and control of process parameters. Examples of successful application of MAO in the production of aviation and automotive components are given. Also, directions for further research and development of the technology are explored, including the creation of new materials, combined coatings and the study of the durability of coatings under real operating conditions. The article emphasizes the importance of MAO as a promising technology for improving the reliability and efficiency of vehicles and equipment.

Facile and effective construction of superhydrophobic, multi-functional and durable coatings on steel structure

Nowadays, steel is one of the most significant materials in industry and daily life. Unfortunately, the defects of steel structures such as collapse at high temperature, poor corrosion resistance, and bad surface functionality have severely restricted their further application. Applying functional coatings for steel structures is considered the effective strategy for settling theses disadvantages. Inspired by nature, eco-friendly, superhydrophobic, and multifunctional-integrated coatings were fabricated on steel via one-step spraying strategy in this paper. Along with silicon dioxide (SiO2) nanoparticles and epoxy resin/silicone resin (EP/SR), the coatings are jointly constituted by hydrophobic flame retardants (M-ALHP@ZIF-8) prepared via multi-stage modification. Due to the formation of micro/nano-scaled rough structure with low surface energy, the water contact angle (WCA) and water sliding angle (WSA) of as-prepared coatings can reach 162.4° ± 1.2° and 2.8° ± 0.4°. The water repellency with low water adhesion can endow the surface of steel with excellent self-cleaning, anti-fouling, and long-lasting anti-corrosion ability. Additionally, the superhydrophobic coatings have displayed good mechanical robustness, chemical stability and weather resistance, which can exhibit certain actual values. Accorded with Zn-catalyzed charring effect of flame retardants, as-prepared coatings have possessed outstanding fire protection capacity with the lowest backside temperature of 181 °C after 1 h fire impact tests. Consequently, this work has provided a facile and effective route for synchronously tackling the key challenges of poor fire protection and surface functionality for steel structures, which will be expected to pave the wide pathway for constructing multifunctional coatings in more fields.

Revealing wear mechanisms of coated shafts in low-speed journal bearings immersed in liquid Lead-Bismuth Eutectic (LBE)

This study investigates wear mechanisms of coated shafts in journal bearings within liquid lead-bismuth eutectic. Shafts were coated with TiAlN, a-C:H, multi-layer TiAlN with sputtered carbon, and chrome plating. Bearings made from sintered iron with carbon inclusions (DEVA 120 and DEVA 121) were tested in LBE at 200 °C and 50 rpm using a dedicated test rig. The a-C:H coatings failed due to tribofilm wear with DEVA 120, while TiAlN coatings failed from fatigue wear with DEVA 120 but succeeded with DEVA 121. Chrome-plated shafts experienced abrasive and adhesive wear with DEVA 121 but survived DEVA 120 due to transfer layer formation. The study highlights the need to understand wear mechanisms and material compatibility to develop durable coatings for harsh environments.

Durable one-component polyurea icephobic coatings with energy-saving performance in electrical heating de-icing

Ice formation and accumulation on the surfaces of aircraft, wind turbines, and boat hulls might result in serious economic losses and catastrophic accidents. The development of a new generation of icephobic surfaces has emerged in recent years for anti-icing. However, insufficient durability of the existing icephobic surfaces remains a significant challenge to their applications. In this study, durable one-component polyurea icephobic coatings (OPICs) with a low ice adhesion strength (∼25.3 kPa) were prepared via a solvent-free method by combining the NCO-terminated prepolymer, latent curing agent, and silicone oil. The chemical structure, surface morphology, wettability, mechanical properties, icephobicity, and durability of the OPICs were studied. The optimized design of OPICs with synergistic icephobic mechanisms endowed them with excellent icephobicity and durability. The superior mechanical durability and chemical stability were revealed by the maintaining icephobicity of OPICs even after 3000 continuous Taber abrasion cycles, as well as 50 icing/de-icing cycles, 72 h of NaOH immersion, and 240 h of neutral salt spray test. The effect of OPICs on minimizing the electric power consumption was further investigated by icing wind tunnel. In comparison to the epoxy primer coated and Al alloy coated airfoil surface, airfoil surface coated by OPIC-30 was found to achieve about 43.7 % and 43.9 % energy savings in the keeping entire airfoil surface ice-free, respectively. The one-component polyurea icephobic coatings have great prospects for practical applications that require long-term anti-icing properties.

Enhancing durability of superhydrophobic surfaces via nanoparticle-induced bipolar interface effects and micro-nano composite structures: A femtosecond laser and chemical modification approach

Superhydrophobic coatings are vital in energy, aerospace, and chemical engineering, while their complex preparation and limited durability hinder widespread application. Therefore, inspired by the unique structures of hydrophobic cotton surfaces and mosquito eyes in nature, a durable aluminum alloy superhydrophobic surface is developed using a combination of femtosecond laser and chemical modification methods. Initially, porous microneedle micro-nanostructures are ablated on the surface of the aluminum alloy via femtosecond laser technology. Then, epoxy resin modified with γ-aminopropyl triethoxysilane (KH550) forms a covalently bonded intermediate layer. Finally, biphasic silicon dioxide (BP-SiO2) nanoparticles modified by hexadecyltrimethoxysilane (HDTMS) are used to construct the top hydrophobic layer. The covalent interface interactions between the aluminum alloy substrate and the intermediate layer, as well as between the intermediate layer and the top layer, significantly enhance the durability of the superhydrophobic surface. The prepared F-M@KH-EP/BP-SiO2 coating exhibits outstanding superhydrophobic properties, with a water contact angle (CA) as high as 168.56° and a sliding angle (SA) as low as 1.52° More encouragingly, the composite coating maintains its excellent water resistance even when subjected to harsh mechanical durability damage, including sandpaper wear, tape stripping tests, water drop and sand impact tests. Moreover, the prepared coatings maintain distinguished non-wettability in harsh operating conditions such as corrosive liquid environments, ultraviolet radiation, ultrasonic vibration, etc. Additionally, the coating demonstrates remarkable self-cleaning properties. Superhydrophobic surface durability is significantly enhanced by combining nanoparticle-induced bipolar interface effect and micro-nano structures. These findings provide theoretical reference for the design and application of durable superhydrophobic coatings.

A facile preparation of durable superhydrophobic PFA coatings with superior anti-icing, anti-corrosion and self-cleaning performance

The potential of superhydrophobic coatings for various applications has been widely recognized. However, preparing durable superhydrophobic coatings on metal surfaces remains a significant challenge. Perfluoroalkoxy Alkane (PFA), a fluorine-rich material, has recently emerged as a promising candidate for constructing superhydrophobic coatings. In this study, a mechanically stable superhydrophobic PFA coating was prepared using a simple combination of electrodeposition and annealing. The prepared PFA coating displays excellent water repellency, as evidenced by a water contact angle of 171 ± 0.3° and a sliding angle of 1.0 ± 0.4° The water contact angle of the coating only decreases by 0.6°after undergoing 400 tape stripping tests, indicating the remarkable stability. The PFA coating significantly prolongs the freezing time of water droplets on a cool surface at temperatures of -6 °C, -8 °C, and -10 °C, with improvements of 19.4, 72.5, and 47.8 times respectively. The corrosion current density on the coated surface is reduced by four orders of magnitude compared to bare aluminum alloy, and the PFA coating exhibits a high inhibition corrosion efficiency of 99.995 %. Furthermore, the coating possesses exceptional self-cleaning performance by repelling dirt particles and maintaining a clean surface. Consequently, the developed superhydrophobic PFA coating holds significant promise for long-lasting anti-icing, anti-corrosion and self-cleaning applications.

Durable and Hydrophobic Self-Healing Coating with Rapid Thermal Activation and Prolonged Corrosion Resistance

Durable and Hydrophobic Self-Healing Coating with Rapid Thermal Activation and Prolonged Corrosion Resistance