Protective Film Research Articles

Tribo-oxidation mechanism of gradient nanostructured Inconel 625 alloy during high-temperature wear

The tribo-oxidation layer is typically formed at the contact interface of high temperature wear, which exhibits a significant effect on the friction behavior of gradient nanostructured (GNS) materials. This study systematically investigated the wear resistance, near-surface microstructure, and compositional changes of ultra-thick GNS Inconel 625 alloy subjected to surface mechanical rolling treatment (SMRT) under high-temperature sliding wear conditions. The experimental results indicated that as the temperature increased to 500 °C, a tribo-oxidation layer was formed on the surface of the GNS sample, thereby resulting in an abnormal increase in the coefficient of friction (COF) and a rapid decrease in the wear rate. The gradient nanostructures facilitated oxidation diffusion channels, promoting the formation of a protective Cr2O3 film and spinel oxides, reducing the wear rate. At lower temperatures, a rapidly formed Cr2O3 film shielded the matrix, forming a tribo-oxidation layer composed of Cr2O3 and nickel. At 800 °C, the tribo-oxidation layer exhibited complex structures, including glaze, spinel oxide, Cr2O3, and Cr2O3/Ni mixed layers. This complexity was attributable to the oxidation diffusion rate of the gradient nanostructures and tribo-oxide layers. The findings not only elucidated the tribo-oxidation mechanism of GNS nickel-based superalloys but also offered valuable insights for designing wear-resistant materials.

Preparation of Smart Self-Healing Coatings on Zinc Surfaces Using Halloysite Nanotubes Loaded with Corrosion Inhibitors.

This work presents the development of a novel nanotube (S12HNTS-T-P) that is coated with polyethylenimine (PEI) and internally loaded with a corrosion inhibitor (thiourea) utilizing vacuum negative pressure and electrostatic adsorption methods. A smart self-healing coating with self-repairing properties was fabricated on the basis of S12HNTS-T-P. Bis[3-(triethoxysilyl)propyl]tetrasulfide (Si69), a widely used organosilane coupling agent, provides stability and corrosion resistance. The integration of S12HNTS-T-P into Si69 significantly enhances the coating's corrosion resistance and self-healing capabilities. To further evaluate the performance of the smart self-healing coating, a control group comprising Si69 coatings without S12HNTS-T-P was established. Electrochemical tests revealed that the coating with 3 wt % S12HNTS-T-P exhibited markedly superior corrosion resistance compared to those with 0, 1, and 5 wt % S12HNTS-T-P. In comparison to the control group, the coating with 3 wt % S12HNTS-T-P demonstrated a 99.4% increase in corrosion inhibition efficiency after 72 h of immersion in a 3.5 wt % NaCl solution. Scanning electron microscopy (SEM) and immersion tests further corroborated that the smart self-healing coating exhibited self-repairing behavior when subjected to external scratching stimuli. Simulation results indicated that thiourea released from the nanotubes can adsorb and form a protective film at the scratch sites, effectively repairing the coating's defects. The exceptional corrosion resistance and high healing rates of the smart self-healing coating suggest that S12HNTS-T-P plays a pivotal role in enhancing the corrosion protection of zinc.

Evaluation of surface properties of modified Ti6Al4V alloy with copper nanoparticles organic nanostructure for biomedical applications: dependency on anticorrosive, antibacterial, and biocompatibility

Abstract In this study, a novel multifunctional copper nanoparticle CuNPs in the organic biomatrix was coated to the surface of Ti6Al4V to create multifunctional features. The synthesis of CuNPs was carried out by plant-mediated green synthesis method obtained from Moringa leaf extract, and the prepared CuNPs were coated on the substrate surfaces as single and double layers with drop casting methods. Characterizations of the synthesized CuNPs were performed by UV–Vis, FTIR, XRD, and SEM methods. Characterization of the modified Ti6Al4V alloy surfaces was performed using SEM-EDS and surface roughness analysis. The electrochemical corrosion, antibacterial behavior, and cytotoxic effects of coated and noncoated Ti6Al4V as a function of biocompatibility properties were also tested. The synthesized CuNPs have a homogeneously dispersed spherical shape. Biocorrosion tests have clearly demonstrated that the coating forms a protective film on the substrate surface, and the resistance increased by 49 %. Antibacterial results show that the single and double-coated Ti6Al4V alloy samples with CuNPs organic nanostructure had improved biocompatibility. However, it was determined that the cytotoxic effect increases proportionally with the coating. The obtained results show the importance of surface modification in the appropriate nanostructure to obtain multifunctional nanoplatforms that show promise in biomedical applications.

Raising the Oxidation Resistance of Low-Alloyed Mg-Ca Alloys Through a Preheating Treatment in an Argon Atmosphere

With the rise and development of aerospace, communications, electronics, medical, transportation and other fields, magnesium (Mg) and its alloys have attracted much attention for their high specific strength and stiffness, good electromagnetic shielding properties, excellent damping properties and other advantages. However, magnesium has a high affinity for oxygen, producing magnesium oxide (MgO), and MgO’s Pilling–Bedworth ratio (PBR) of 0.81 is not protective. The occurrence of catastrophic oxidation is unavoidable with the increase of oxidation time and temperature. A promising approach is to perform an appropriate pretreatment in conjunction with alloying to obtain a dense and compact composite protective film. In this work, the effect of a preheating treatment on the oxidation resistance (OR) of Mg-xCa (x = 1, 3 and 5 wt. %) was investigated. The preheating was carried out in an Ar atmosphere at 400 °C for 8 h. Upon it, a dense and compact MgO/CaO composite protective film was formed on the surface, which is CaO-rich especially in the vicinity to the surface. The alloys’ oxidation resistance was strongly increased due to the composite protective film formed during the preheating treatment, in particular for Mg-3Ca. Relative to the Mg-hcp phase, the OR of the Mg2Ca phase was significantly raised.

Electrode/Electrolyte Optimization-Induced Double-Layered Architecture for High-Performance Aqueous Zinc-(Dual) Halogen Batteries

HighlightsA double-layered protective film based on zinc-based coordination compound and ZnF2-rich solid electrolyte interphase layer has been successfully fabricated on the zinc metal anode via electrode/electrolyte synergistic optimization.The double-layered architecture can effectively modulate Zn2+ flux and suppress the zinc dendrite growth, thus facilitating the uniform zinc deposition.The as-developed zinc-(dual) halogen batteries based on double-layered protective film can present high areal capacity and satisfactory cycling stability.

Effect of Combined Addition of La and Sm on Mechanical Properties, Microstructure Evolution, and Electrochemical Behavior of Mg-3Zn-1Mn/Sn-0.5Ca Alloy

The effects of the composite addition of La and Sm elements on the microstructural evolution, mechanical properties, and electrochemical behaviors of Mg-3Zn-1Mn/Sn-0.5Ca (wt.%) alloys are systematically investigated. The findings reveal that the Mg-3Zn-1Mn-0.5Ca alloy exhibits excellent ductility, achieving 26% elongation, whereas the Mg-3Zn-1Sn-0.5Ca alloy demonstrates good comprehensive mechanical properties. The addition of La and Sm results in a degree of grain refinement in both alloys and significantly bolsters the strength of the Mg-3Zn-1Mn-0.5Ca alloy, but it has a less pronounced effect on the mechanical properties of the Mg-3Zn-1Sn-0.5Ca alloy. Furthermore, the addition of La-Sm significantly improves the corrosion resistance of both alloys. Electrochemical impedance spectroscopy (EIS) analysis reveals that all four alloys form a double-capacitance loop morphology in 3.5% NaCl, indicating the formation of a protective film during the corrosion process. Among them, the Mg-3Zn-1Mn-0.5Ca-1La-0.5Sm alloy exhibits the largest capacitance loop radius, which is consistent with its polarization curve, indicating the best corrosion resistance. At the corrosion potential of −1.382V, the corrosion current is 8.97 μA·cm−2.

Insights into the corrosion inhibition performance of essential oil of Teucrium luteum subsp. flavovirens for carbon steel in 1.0 M HCl medium: experimental and theoretical evaluations

The objective of this research work was to assess Teucrium luteum subsp. flavovirens essential oil (EOTL), for the first time, as novel and eco-friendly corrosion inhibitor for carbon steel (CS) in 1.0 M HCl medium. Electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP) and surface analysis were employed to assess the effectiveness of the EOTL. The findings indicate that the EOTL reduces the corrosion of CS in hydrochloric acid and offered an inhibition efficiency (IE) of 91% at a dosage of 2.00 g/L at 298 K. The PDP data showed that EOTL behaved as a mixed-type corrosion inhibitor. The effect of immersion time and temperature on the corrosion inhibition performance of EOTL was also studied. It was found that the IE increased only up to 24 h and decreased with prolonged immersion time. In addition, the IE diminished with increasing temperature. The EOTL molecules adsorbed on the CS surface following Langmuir adsorption isotherm, with an adsorption energy ranging from −16 to −27 kJ/mol, an indication of physico-chemical adsorption mechanisms. The SEM/EDX results provide evidence of the presence of a protective film of the inhibitor on the surface of the CS. Theoretical studies using DFT, Monte Carlo simulations, molecular dynamics simulations and mean square displacement were conducted to given insight into the contributions of the four main components of EOTL. This work not only introduces a sustainable alternative to conventional corrosion inhibitors but also provides a robust understanding of the underlying mechanisms, hence contributing to advancement in corrosion science.

Unveiling the interaction between corrosion products and oxygen reduction on the corrosion of Mg–4Nd–0.4Zr alloy under thin electrolyte layers

Although hydrogen evolution reaction (HER) is considered to be the main cathodic reaction of Mg corrosion, oxygen reduction reaction (ORR) has been recently confirmed to be a secondary cathodic reaction. The factors affecting ORR of magnesium (Mg) alloys are still unclear, especially in cases under thin electrolyte layers (TEL). In this work, the influence of the corrosion product films on the cathodic reactions of Mg alloys under TEL and in a bulk solution was investigated. ORR does not influence the hydrogen evolution rates in the corrosion of Mg alloys. Therefore, with the existence of oxygen, corrosion rates of Mg alloys measured by hydrogen evolution tests are not accurate under TEL. And weight loss test is a more accurate method to evaluate Mg corrosion rates under TEL. ORR was confirmed to participate in the corrosion of Mg–4Nd–0.4Zr, Mg–4Nd and Mg–0.4Zr alloys under TEL. In 100-μm TEL, the highest contribution of ORR in cathodic reactions for the corrosion of Mg–4Nd–0.4Zr, Mg–4Nd and Mg–0.4Zr alloys are 28.6%, 39.1%, and 35.8%, respectively. The more protective film on Mg–4Nd–0.4Zr alloy provides a stronger inhibition effect against the diffusion of oxygen, leading to decreased ORR contribution in cathodic reactions. In addition, it is suggested that the preparation of Mg alloys with protective corrosion product films can inhibit the corrosion induced by ORR in the atmosphere. This work emphasizes the effects of corrosion product films on ORR in Mg corrosion, especially under TEL.

A biomacromolecular additive based on pullulan polysaccharide to enhance the life of lead-acid battery packs in DC systems

Abstract With the rapid growth in demand for mobile power, lead-acid batteries still occupy a large market share due to their excellence in energy storage. However, their lifespan is affected by various factors, which limits the application efficiency and environmental friendliness. In this regard, this paper proposes a method to enhance the service life of lead-acid battery packs by applying biomacromolecule additives. A lead-acid battery pack modification method is investigated by introducing chitosan, a natural macromolecule with excellent electrical conductivity and biodegradation properties, into lead-acid batteries. So that the chitosan-modified material forms a stable and protective film on the surface of the battery electrode plate, thereby reducing the analysis of sulphate crystals on the electrode surface. The method of modification of lead-acid battery packs has been studied. Comparative analysis of the experimental data shows that the modified battery pack exhibits lower charge transfer impedance and better electrochemical stability than the traditional lead-acid battery during the cyclic charge/discharge test. Through the cycle charge/discharge test, the energy loss of the battery with biomolecules is 30% lower than that of the unmodified battery, and the number of charge/discharge cycles increases by 60%, which effectively prolongs the service life of the lead-acid battery. The progress of this paper not only has guiding significance for the performance improvement of traditional lead-acid batteries but also provides a significant theoretical and experimental basis for the development and application of environmental friendly battery materials.

Preparation of Multi-element Doped Carbon Nanospheres with Core-shell Structure Derived from Polystyrene as Lubricating Additives for Improving Tribological Behavior

In this study, the multi-element doped carbon nanospheres with core-shell structure (N,P,S-PCNs) have been successfully synthesized through the carbonization of hyper-cross-linked polystyrene nanospheres (HPSs) encapsulated with poly(cyclotriphosphazene-co-4,4’-sulfonyldiphenol) (PZS). The phosphonitrilic chloride trimer can in-situ assemble on HPSs surface, forming a poly(phosphonitrilic chloride trimer) film via sulfonyldiphenol as cross-linking agent to obtain HPSs@PZS. Subsequently, the HPSs@PZS undergoes high-temperature calcination under N2 atmosphere, and PZS with a well-preserved encapsulation capability efficiently incorporated N, P and S into carbon nanospheres to gain multi-element (N,P,S) co-doped carbon nanospheres (N,P,S-PCNs) with core-shell structure. The prepared N,P,S-PCNs exhibit exceptional dispersibility and stability as lubricant additives, effectively mitigating friction (reduced to 0.106) and wear (decreased by 84.0 %). The lubrication performance of N,P,S-PCNs is exceptional due to the nanospheres' remarkable ability to enter the gaps between friction pairs and form a deposition film on the surfaces. Moreover, the nanospheres can undergo a chemical reaction with the matrix surface, resulting in the formation of a chemical protective film. The composite protective film (deposition film and chemical protective film) significantly enhances the lubricants' ability to reduce friction and resist wear.

Protective Ni composite film on Cu prepared by inverse-replacement reaction

Protective Ni composite film on Cu prepared by inverse-replacement reaction

Promising corrosion resistance of mild steel, copper, and aluminum in hydrochloric acid solution using an environmentally friendly corrosion inhibitor

The current study assessed the anticorrosion features of 6-chloro-2-(4-chlorophenyl)imidazo[1,2-a]pyridine-3-carbaldehyde (AIM) in mitigating corrosion of three different metals: Mild Steel (MS), Copper (Cu) and Aluminum (Al) in 1 M HCl solution. The adsorption process of AIM on these metal surfaces, as well as the stability of the adsorbed layer and its relationship with the type of metal were comprehensively investigated. To achieve our objectives, several techniques were used, such as: Potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), SEM surface characterization, and theoretical approaches. Electrochemical impedance spectroscopy investigations revealed high corrosion inhibition rates, reaching 99.01 %, 96.06 %, and 84.8 % for Cu, MS and Al, respectively, at a concentration of 10−3 M of AIM. Potentiodynamic polarisation validated the mixed type nature of inhibitor, a satisfactory correlation was observed between the results obtained by EIS and those obtained by the PDP technique. The adsorption study showed that the process was mainly controlled by chemical adsorption, and metal dissolution was an endothermic process. Additionally, surface analysis by scanning electron microscopy (SEM) confirmed the formation of a protective AIM film on the electrode surface, resulting in a significant reduction in metal dissolution in the presence of aggressive ions. The exploration of the relationship between molecular structure, inhibitory properties of AIM and the studied metals, was conducted through quantum chemical analysis and dynamic molecular simulation.

Ability of a MoSi2 coating to resist erosion-corrosion from the impact of atomic oxygen

Atomic oxygen (AO), in the residual atmosphere of low-Earth-orbit space, may violently collide with spacecraft at a relative speed of up to 8 km/s and an impact energy of nearly 5 eV/atom. These collisions can lead to a series of physical and chemical reactions that may result in increased sputtering-erosion and corrosion of the exposed surface with performance degradation. This work examined the behavior of MoSi2, a commonly used coating, when exposed to AO using a ground-based space environment simulator. The erosion-corrosion kinetics and evolution of the microstructure and element distributions were analyzed. After MoSi2 was subjected to a total gas fluence of 9.72×1022 atoms/cm2 in 675 h, the erosion yield reached an exceptionally low value of 10-28 cm3/atom, indicative of its superior AO resistance, and XRD, SEM, XPS and EPMA were applied to analyze the phase transition of the coating surface: first it was released of adsorbed gas molecules and contaminants on the coating surface; then outside Mo and Si atoms were also sputtered, and the remaining Mo and Si atoms were gradually oxidized; finally, a continuous protective oxide film was generated which effectively resisting AO collisions. After AO impact, an ultrathin defensive granular oxide layer of MoO3 and SiO2 generated from the original smooth MoSi2 coating. Density functional theory calculations were conducted to clarify the thermodynamic and electronic structure mechanisms underlying the AO oxidation of the MoSi2 coating.

A significant improvement in corrosion resistance and biocompatibility in ZrNbTiCrCu high-entropy films induced by the precipitation of Cu

Utilizing nanotechnology and composites to create a protective film on titanium alloy is an effective means of achieving the desired high performance. Self-assembly of nanocomposite structures offers a promising route to forming high entropy alloy films (HEAFs), but controlled preparation remains challenging. This work used magnetron sputtering through adjusting preparation parameters to prepare ZrNbTiCrCu HEAFs, achieving a significant improvement in corrosion resistance and biocompatibility induced by the precipitation of Cu. According to the electrochemical corrosion test, without obvious corrosion pits on the surface of S2 after corrosion, a passivation film composed of bimetallic oxide CuCrO2 formed on the film surface, indicating that ZrNbTiCrCu HEAFs have remarkable corrosion resistance performance. In the cytocompatibility experiment, the cell viability of HEAFs reached over 95 % due to the precipitation of Cu, suggesting their excellent biocompatibility. In addition, ZrNbTiCrCu HEAFs exhibit outstanding antibacterial ability, especially when the sputtering current is 0.6 A, and the in vitro antibacterial rate of the sample against Escherichia coli is close to 99 %.

Optimizing laser parameters and exploring building direction dependence of corrosion behavior in NiTi alloys fabricated by laser powder bed fusion

The microstructure and materials performance of Laser Powder Bed Fusion-fabricated (LPBFed) NiTi shape memory alloys (SMAs) varies depending on the laser parameters and building directions. This study initially optimized the laser processing parameters (laser power and scanning speed) for LPBFed NiTi SMAs to enhance their printing quality and mechanical properties. We determined that with fixed hatch spacing of 80 μm and layer thickness of 30 μm, the laser power of 105 W, and scanning speed of 600 mm/s produced the best results. Subsequently, the corrosion behavior of LPBFed NiTi SMAs built in three different building directions (0°, 45°, 90°) was investigated in 0.9 wt.% NaCl solution at 37 °C. The electrochemical data revealed that the corrosion current density (Icorr) decreased with increasing building direction angle (Icorr-90° <Icorr-45° <Icorr-0°). The corrosion resistance followed the order of 0° sample ˂ 45° sample ˂ 90° sample. These findings were attributed to the difference in the grain size and boundary density. Higher boundary densities enhanced the electron activity capacity and the element diffusion rates, facilitating the rapid formation of a protective film and thus improving the corrosion resistance. This new insight into the anisotropy of corrosion behavior relative to building directions can inform the design of NiTi-SMA products and improve their reliability in tissue engineering applications.

Bio-Based Polyurethane Composites with Adjustable Fluorescence and Ultraviolet Shielding for Anti-Counterfeiting and Ultraviolet Protection.

Polyurethane and its composites play an important role in innovative packing materials including anticounterfeiting and ultraviolet protection, however, they are mainly derived from petroleum resources that are not sustainable. In this study, a 100% biobased thermoplastic polyurethane (Bio-TPU) was synthesized using biobased poly(trimethylene ether) glycol, pentamethylene disocyanate, and 1,4-butanediol. Subsequently, biobased tannic acid (TA) was employed to prepare biobased composites. The structures and properties of Bio-TPU and its composites were systematically evaluated. The results showed that the Bio-TPU/TA composite films had excellent and controllable fluorescence and UV-shielding properties. The fluorescence colors of the Bio-TPU/TA composite films could be adjusted to blue, green, and yellow by varying the TA content and adding coupling agents. Moreover, the UV transmittance of the Bio-TPU/TA composites decreased from 79.25 to 5.43% below 400 nm with an increasing TA content, indicating an excellent ultraviolet-barrier performance. Consequently, biobased TPU/TA composite films can be utilized as innovative anticounterfeiting materials and UV-shielding protection films. This study is expected to facilitate sustainable development in the polyurethane industry and broaden the high-end applications of polyurethane such as fashion, electronics, food manufacturing, pharmaceuticals, and finance.

Synthesis and Evaluation of New Type Plant Extraction Corrosion Inhibitor

The use of corrosion inhibitors in the development of oil and gas fields is an important means of effectively preventing metal corrosion, at present, the green growth of the oil and gas industry requires low-toxicity, low-residue, easy-to-post-treatment and other environmentally friendly corrosion inhibitors, however, most industrially used corrosion inhibitors such as mercury salts quaternary ammonium salts, and imidazolines are toxic to some degree. In this paper, a plant extract corrosion inhibitor was synthesized, firstly, the purple sweet potato extract was extracted by ethanol, and then the purple sweet potato extract and alkyl halide such as methane were used to produce the purple sweet potato corrosion inhibitor through condensation extraction and other processes, and the corrosion inhibitory performance of the inhibitor was evaluated by the loss-in-weight method, scanning electron microscopy, polarization curves, and impedance spectroscopy. The results show that there is a certain inhibition effect on N80 steel in the simulated stratum water environment, and the retardation rate can reach 91.38% in the gas phase, and the corrosion product morphology and chemical elements on the surface of N80 steel specimens were characterized by SEM, EDS, and it can be observed that a relatively dense protective film was formed after adding purple sweet potato corrosion inhibitor, and the corrosion inhibition rate can be known according to the weightlessness curve, Tafel curve and impedance curve. The corrosion inhibition rate increases with the increase of corrosion inhibitor concentration.

Evaluation of 14-(p-tolyl)-14H-dibenzo[a,j]xanthene as a Highly Efficient Organic Corrosion Inhibitor for Mild Steel in 1 M HCl: Electrochemical, Theoretical, and Surface Characterization

Corrosion of mild steel, particularly in acidic environments such as hydrochloric acid (HCl), remains a critical issue due to its impact on material durability, economic costs, and safety concerns. This study introduces 14-(p-tolyl)-14H-dibenzo[a,j]xanthene (ZM5), a novel and highly effective organic corrosion inhibitor, to mitigate this challenge. Employing advanced electrochemical techniques: electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP), we evaluated ZM5’s performance in a 1M HCl solution, revealing an impressive inhibition efficiency of 94.7%. Surface characterization using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) further confirmed the formation of a robust protective film on the steel surface, shedding light on ZM5’s adsorption mechanisms. Complementing the experimental findings, Density Functional Theory (DFT) simulations provided theoretical insights into the anti-corrosion mechanism of ZM5, aligning well with observed results. These findings underscore ZM5's potential as a highly promising corrosion inhibitor for industrial applications, effectively enhancing the corrosion resistance of mild steel in aggressive environments.

Exploring the Bio-inspired Corrosion Inhibition Properties of Eco-friendly Limonia Acidissima Leaves Extract for Mild Steel in Acidic Media: Computational, Electrochemical and Spectroscopic Insights

This study investigates the corrosion inhibition properties of Limonia acidissima leaves extract (LALE) on mild steel in a 1.0 M HCl medium. Utilizing mass loss measurements, potentiodynamic polarization, AC impedance spectroscopy, and surface characterization methods like SEM, AFM, UV-Vis, and fluorescence spectroscopy, the study reveals significant findings. The maximum inhibition efficiency of LALE was attained to be 92.26% at a 1.0% concentration. Potentiodynamic polarization studies show a marked decrease in corrosion current density (Icorr) from 3.102 × 10-3 A/cm² for the blank solution to 3.165 × 10-4 A/cm² with 1.0% LALE, indicating mixed-type inhibition. AC impedance measurements show an increase in charge transfer resistance (Rct) from 2.1410 Ω in the blank solution to 8.6580 Ω with 1.0% LALE, and a decrease in double-layer capacitance (Cdl) from 7.757 × 10-7 μF/cm² to 1.926 × 10-7 μF/cm², suggesting the formation of a protective film. SEM and AFM analyses confirm that LALE-treated steel surfaces are smoother with fewer pits and cavities compared to untreated steel. Furthermore, DFT analysis complemented well with the empirical findings. This research highlights the potential of plant extracts in industrial applications for corrosion protection, contributing to the growing body of knowledge on sustainable corrosion inhibitors and offering practical insights for future research and application in various corrosive environments.

Constructing dual-ligand Ce-MOF on graphene oxide modified with polydopamine endowing polyurethane coating with long-term smart anti-corrosion and mechanical robustness

Traditional mono-functional anti-corrosion coatings are unable to meet the long-term corrosion resistance requirements of metal materials, therefore developing multifunctional anti-corrosion coatings have broad application prospects. In this work, long-lasting anti-corrosion coatings with superhydrophobic and self-healing properties were successfully prepared by in-situ growth of dual-ligand cerium-based metal–organic framework (Ce-MOF) on the surface of graphene oxide (GO), followed by chemical modification with polydopamine (PDA), resulting in 5B level of adhesion and excellent mechanical robustness. The superhydrophobic surface, as the external armor of the coating, can effectively block the penetrating path of corrosive media. Meanwhile, the MOF structure formed by the coordination of 2-mercaptobenzimidazole (2-M) with cerium ions endows the coating with smart self-healing properties and long-lasting corrosion resistance. Electrochemical tests showed that the low-frequency impedance modulus value of the superhydrophobic coating still reached 3.82 × 108 Ω cm2 after 30 days salt immersion. Due to the formation of protective films and insoluble precipitates at the defect site by 2-M and cerium ions, the scratches on the coating were significantly reduced after 40 days salt spray experiment, demonstrating the self-healing ability of the coating. This multifunctional anti-corrosion coating provides a new approach for preparing coatings with long-term effective corrosion resistance.