ZnO/CeO2 and CeO2/ZnO composite films were prepared by combining electrodeposition with hydrothermal methods. The study focused on how the heterojunction interface affects the resistance behavior and corrosion resistance of the films. The surface morphology, composition, structure, semiconductor type, and oxygen vacancy concentration of the films were observed and analyzed. Furthermore, the surface adsorption energy, oxygen vacancy formation energy, heterojunction binding energy, and diffusion barrier energy were calculated using density functional theory (DFT). The corrosion resistance and resistance switching properties of the films were examined through electrochemical methods tests. The results show that the oxygen vacancy concentration in the CeO2/ZnO film is lower than in the single-layer thin film (ZnO, CeO2), and its corrosion resistance is higher than that of the single-layer film. Conversely, ZnO/CeO2 film exhibits the opposite trend. After applying a polarization voltage, the formation energy and diffusion barrier of oxygen vacancies in the CeO2/ZnO system decrease, and the applied voltage promotes the generation and migration of oxygen vacancies. The polarization treatment enables cyclic switching between high and low resistance states, which significantly extends the film's service life and is expected to expand the application of resistance switching technology in the field of corrosion protection.

Purpose The purpose of this paper is to develop high-performance anticorrosive epoxy coatings by regulating the orientation of two-dimensional (2D) nanosheets. This is achieved by synthesizing superparamagnetic boron nitride nanosheets (m-BNNSs) and applying a parallel external magnetic field to induce highly ordered in-plane alignment. Design/methodology/approach Few-layer BNNSs prepared via liquid-phase exfoliation were functionalized with Fe3O4 nanoparticles through in situ co-precipitation to obtain Fe3O4/BNNSs (denoted as m-BNNSs). These fillers were incorporated into an epoxy matrix with a parallel magnetic field applied during curing. Composite structures and magnetic behavior were verified by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and vibrating sample magnetometer. Electrochemical measurements and pull-off adhesion tests were conducted to evaluate the anticorrosion performance and coating-substrate bonding strength, respectively. Findings Application of a 200 mT magnetic field successfully reduced the average tilt angle of m-BNNSs from 46.1° ± 27.0° to 12.5° ± 12.0°, achieving highly ordered parallel orientation. The coating with 1.0 wt % m-BNNSs under a 200 mT field exhibited the best performance, maintaining a low-frequency impedance modulus of 1.52 × 109 Ω·cm2 after 30 days of immersion. Pull-off tests confirmed that the filler incorporation and magnetic alignment did not significantly alter the coating adhesion. However, excessive filler loading or higher field strengths (300 mT) caused possible local re-stacking and structural defects, leading to the deterioration of protective performance. Originality/value This work provides an effective strategy for regulating the orientation of inert 2D nanosheets in polymer coatings. The enhanced long-term protection is attributed to the synergistic effects of Fe3O4 spacers in suppressing restacking and the field-induced alignment in maximizing the tortuous diffusion path for corrosive species.

Abstract Material corrosion represents a significant scientific and engineering challenge. Microorganisms on material surfaces accelerate corrosion. Due to the excellent properties of graphene, bifunctional anticorrosion and antibacterial coatings were developed by incorporating graphene into epoxy resin. To mitigate the detrimental effects of agglomeration on coating performance, graphene oxide (GO) was prepared, and a silane coupling agent was used to modify the surface of GO to enhance its stability and dispersibility within the coating matrix. The properties of graphene were analyzed before and after surface modification by Fourier transform infrared spectroscopy (FTIR) and Transmission electron microscope (TEM). Epoxy/modified-GO (0.1 wt%) coating revealed the highest corrosion resistance of 9.696 × 10 7 Ω cm 2 after 144 h immersion in 3.5% NaCl solution measured by the electrochemical impedance spectroscopy (EIS) technique. Higher protection against bacteria was observed for epoxy/modified-GO (0.1 wt%) as the most efficient antibacterial composite coating. These results indicated that the coatings with modified graphene exhibited superior corrosion resistance and effectively inhibited the growth of Staphylococcus aureus .

Purpose This study aims to fabricate an efficient hydrophobic anticorrosion coating in situ on Q235 steel by combining electrodeposition with hydrophobic surface modification, and to clarify its corrosion protection mechanism.Design/methodology/approach Zeolitic imidazolate framework (ZIF)-90 coatings were electrodeposited on Q235 steel and subsequently modified with octadecylamine (ODA) to obtain hydrophobic ODA-ZIF-90 coatings. The morphology and structure of the coatings were characterized by scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy, while the hydrophobicity was evaluated by water contact angle measurements. The corrosion resistance was investigated by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and immersion tests in NaCl solution.Findings The as-prepared ODA-ZIF-90 coating significantly enhanced the corrosion resistance of Q235 steel and exhibited a water contact angle above 140 degrees. EIS results showed that the impedance value reached 1.38 x 109O.cm2. Potentiodynamic polarization measurements indicated that the corrosion current density decreased markedly, with an inhibition efficiency of 99%. After immersion in 3.5 Wt.% NaCl solution for 14 days, the corrosion protection efficiency remained above 91%. However, after 21 days of immersion, the impedance value decreased significantly, indicating severe coating degradation and loss of effective protection.Practical implications This study develops a simple, cost-effective and efficient method to in-situ fabricate hydrophobic corrosion-resistant coatings on carbon steel via electrodeposition. The prepared ODA-ZIF-90 coating significantly enhances the corrosion resistance of Q235 steel, while greatly reducing the preparation time compared with conventional anticorrosion coating methods. In addition, the multifunctionality of metal-organic framework (MOF) materials provides abundant modification possibilities, enabling the design of coatings with different functional properties according to specific application requirements. This work offers a promising strategy for the rapid preparation of high-performance MOF anticorrosion coatings.Originality/value This study proposes a simple and effective strategy for constructing corrosion-resistant coatings on carbon steel surfaces through electrodeposition combined with hydrophobic surface modification of a MOF. It provides a feasible route for the economical, efficient and rapid fabrication of MOF-based anticorrosion coatings, thereby effectively improving the corrosion resistance of Q235 steel.

Purpose This study aims to optimize electrodeposition parameters for ZnAl-layered double hydroxides (LDHs) films on Q235 steel and modify them for enhanced corrosion protection.Design/methodology/approach ZnAl-LDHs films were electrodeposited on Q235 steel. Key parameters (pH, Zn2+/Al3+ ratio, potential, time) were optimized via univariate and orthogonal experiments. Films were then modified with perfluorodecyltrimethoxysilane (PFDTMS) for superhydrophobicity. Morphology, structure, wettability and corrosion resistance were characterized by SEM, XRD, FTIR, contact angle and electrochemical tests in 3.5 Wt.% NaCl.Findings Optimal parameters: c(Zn2+):c(Al3+)=2:1, pH = 3.8, -1.5 V, 600 s. The ZnAl-LDHs film showed good crystallinity and corrosion resistance. After PFDTMS modification, it became superhydrophobic (contact angle 160 degrees, sliding angle 2.1 degrees), with significantly enhanced corrosion resistance maintained after 10 days immersion, demonstrating durable protection.Originality/value A facile, efficient and green electrodeposition method was developed for ZnAl-LDHs films on carbon steel, with parameters optimized via combined univariate/orthogonal experiments, offering an effective strategy for protective coatings.

The corrosion-resistant behavior of the films was investigated in conjunction with the principle of resistive switching, and the films were subjected to continuous repair by modulating the oxygen vacancies. Zn1-xCexO resistive switching film was prepared on SS304 surface by one-step hydrothermal method combined with the following heat treatment. The surface morphology, crystal structure, composition, oxygen vacancy concentration and semiconductor type of Zn1-xCexO film were determined. The corrosion resistance and resistive switching properties of Zn1-xCexO films were measured by electrochemical tests, immersion experiment and resistive switching experiment. The oxygen vacancy formation energy, surface adsorption energy and diffusion energy barrier energy of Zn1-xCexO film were calculated by density functional theory (DFT). The experimental results show that with the increasing of Ce doping concentration, the nano-flowers on the surface of Zn1-xCexO film become sparse, and the lattice constants a and c increase, the oxygen vacancy concentration of the film gradually increases, while the corrosion resistance of Zn1-xCexO film decreases. The corrosion resistance of Zn 0.98 C e0.02 O film is the best (99.36%). During resistive switching process, the polarization treatment will promote the conversion of Ce3+ to Ce4+ in film, reduce the formation energy and diffusion barrier of oxygen vacancies, and thus promote the formation and migration of oxygen vacancies in film and then convert the film into a low resistance state. Zn1-xCexO films can stably switching between high and low resistance states, maintaining excellent corrosion resistance, which is of great significance for expanding the application of resistance switching principles in the field of corrosion protection.

Zn1-xLaxO film was prepared on SS304 steel surface by using hydrothermal method combined with the following heat treatment. The morphology, structure, composition, oxygen vacancy concentration and semiconductor type of film were determined. The corrosion resistance and resistive switching properties of film were analyzed by electrochemical tests and polarization-immersion experiments. The oxygen vacancy formation energy, surface adsorption energy and diffusion energy barrier of films were calculated by density functional theory (DFT). The experimental results show that the polarization treatment enables Zn1-xLaxO films switch between high and low resistance states cyclically and stably, and the excellent corrosion resistance and durability are achieved through resistive switching behavior of films. Polarization treatment can reduce the formation energy and diffusion barrier of oxygen vacancies, promoting the formation of oxygen vacancy conductive filaments in the thin film. Regulating the formation and fracture of oxygen vacancy conductive filaments can achieve cyclic switching between high and low resistance states. The film is in a state of constant repair, preventing the invasion of corrosive media through the formation and annihilation of oxygen vacancies, which provides a novel corrosion protection strategy.

PurposeThe purpose of this paper is to prepare smart coatings with self-healing and self-reporting dual functionalities.Design/methodology/approachBenzotriazole (BTA) and 1,10-phenanthroline-5-amine (APhen) were encapsulated within mesoporous silica nanocontainers (MSN) via one-step method. Then, BTA+APhen@MSN were mixed with epoxy for preparing BTA+APhen@MSN/EP coatings. The microstructure, structure and sustained-release properties of BTA+APhen@MSN nanocontainers were investigated by transmission electron microscopy, Fourier-transform infrared spectroscopy, Brunauer-Emmett-Teller analysis and UV-Vis spectroscopy. The warning performance and corrosion resistance of BTA+APhen@MSN/EP coatings were characterized by optical microscopy and electrochemical impedance spectroscopy.FindingsBTA+APhen@MSN exhibit higher corrosion inhibitors loading capacity (31.2 wt.%) and higher corrosion inhibition efficiency (53.07%) than BTA@MSN and APhen@MSN. The BTA+APhen@MSN/EP coatings show excellent self-healing performance. After soaking in 3.5 wt.% NaCl solution for five days, the fitted resistance of scratched coatings increased by 18%. The BTA+APhen@MSN/EP coatings also show superior self-reporting capability, which can provide a warning of coating damage within 30 min by a visible color change.Originality/valueThe corrosion inhibitors and corrosion warning agent are encapsulated in a nanocontainer to prepare multifunctional nanocomposite. This multifunctional nanocomposite presents a new approach for designing smart coatings with self-healing and self-reporting dual functionalities.

Purpose The purpose of this paper is to prepare a multifunctional nanocomposite that is slow-release and resistant to seawater corrosion and biofouling corrosion and to explore the synergistic effect between the two corrosion inhibitors. Design/methodology/approach The morphology, structure and release properties of CAP@HNTs, BTA@HNTs and CAP/BTA@HNTs were investigated by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, specific surface area analysis and UV spectrophotometry. The corrosion resistance and antimicrobial properties were investigated by electrochemical measurements and bioinhibition rate tests, and the synergistic effect between the two corrosion inhibitors was explored by X-ray photoelectron spectroscopy. Findings The CAP/BTA@HNTs are responsive to acidic environments and have significantly improved antibacterial and corrosion resistance compared with CAP@HNTs and BTA@HNTs. CAP and BTA have a positive synergistic effect on anticorrosion and antifouling. Originality/value Two types of inhibitors, anticorrosion and antifouling, were loaded into the same nanocontainer to prepare a slow-releasable and multifunctional nanocomposite with higher resistance to seawater corrosion and biocorrosion and to explore the synergistic effect of CAP and BTA on corrosion resistance.

This paper focuses on the preparation and evaluation of a novel humidity-control material, vermiculite/(sodium polyacrylate(AA)–acrylamide(AM)), using inverse suspension polymerization. Acrylic acid and acrylamide were introduced into the interlayer of modified vermiculite during the polymerization process, leading to the formation of a strong association with the modified vermiculite. The addition of vermiculite increased the specific surface area and pore volume of the composites. To investigate the moisture absorption and desorption properties of the composites, an orthogonal experiment and single-factor experiment were conducted to analyze the impacts of vermiculite content, neutralization degree, and the mass ratio of AA to AM. According to the control experiment, the addition of vermiculite was found to enhance the pore structure and surface morphology of the composite material, surpassing both vermiculite and PAA-AM copolymer in terms of humidity control capacity and rate. The optimal preparation conditions were identified as follows: vermiculite mass fraction of 4 wt%, a neutralization degree of 90%, and mAA:mAM = 4:1. The moisture absorption rate and moisture release rate of the composite material prepared under these conditions are 1.285 g/g and 1.172 g/g. The humidity control process of the composite material is governed by pseudo second-order kinetics, which encompasses the complete adsorption process. These results indicate that the vermiculite/PAA-AM composite humidity control material has excellent humidity control performance and is a simple and efficient humidity control method.

Montmorillonite (MMT) film was prepared on the surface of alkali-heat treated Mg alloys by one-step hydrothermal method. The structure and composition of MMT film were characterized using scanning electron microscopy, energy dispersive spectroscopy, X-ray diffractometry, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The corrosion resistance of MMT film in simulated body fluid (SBF) was investigated using electrochemical tests and immersion experiments. The experimental results showed that with the extension of hydrothermal time, the corrosion resistance of film increased and then decreased. With the increase of MMT powder mass fraction in precursor solution, the corrosion resistance of films also increased and then weakened. The best performance of MMT films was obtained at hydrothermal time of 12h and MMT powder mass fraction of 2wt.%, with an impedance value of 9.77×106 Ω·cm2, which is an improvement of four orders of magnitude compared to substrate, and the efficiency of corrosion protection was up to 100%. The ion exchange properties, barrier effect and inertness characteristics of MMT provide excellent corrosion protection for magnesium substrates. This study provides a new coating strategy for the preparation of biodegradable magnesium alloys with excellent corrosion resistance and biocompatibility for use as biomedical materials.

•ZnO resistive switching film is prepared by one-step hydrothermal method.•Application of electric field can promote the formation of oxygen-vacancy in film.•High-low resistive switching behavior of film varies with oxygen vacancy content.

Zn1-xCrxO resistive switching film with different Cr content was prepared on SS304 substrate by sol–gel method combined with spin plating and heat treatment. The surface morphology, composition, structure, semiconductor type and oxygen vacancy concentration of Zn1-xCrxO films were observed and analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Mott-Schottky curves, X-ray photoelectron spectroscopy (XPS) electron paramagnetic resonance spectroscopy (ESR) and density functional theory (DFT) calculation. And the corrosion resistance of Zn1-xCrxO film were investigated by polarization curves and electrochemical impedance spectroscopy (EIS). The results show that the prepared Zn1-xCrxO films have a uniform dense surface which belongs to n-type semiconductor type, and the oxygen vacancy concentration in the films increases with the increase of Cr content. With the increasing of Cr content, the corrosion resistance of films is decreased. During the immersion process, the corrosion resistance of Zn1-xCrxO film is firstly increased and then decreased with increasing immersion time. By applying immersion and polarization treatment the corrosion resistance of Zn1-xCrxO film could be regulated between the high and low resistance states (HRS and LRS) due to the creation and disappearance of oxygen vacancies in the film.

The nickel-ferric layered double hydroxides (NiFe-LDHs) film which are commonly used as catalysts was fabricated on Q235 steel in-situ via two-step hydrothermal method. And the superhydrophobic NiFe-LDH-PFDTES film was obtained by 1 H, 1 H, 2 H, 2 H-perfluorodecyltriethoxysilane (PFDTES) modification. To a certain extent, the application of NiFe-LDHs has been broadened. The structure and composition of NiFe-LDHs film and NiFe-LDH-PFDTES film were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrometer (EDS), and Fourier transform infrared (FT-IR). The wettability of films was analyzed by water contact angle testing. And the corrosion resistance of NiFe-LDHs and NiFe-LDH-PFDTES film in 3.5 wt% NaCl solution were measured by using potentiodynamic polarization curve and electrochemical impedance spectroscopy (EIS) techniques. The results show that NiFe-LDHs and NiFe-LDH-PFDTES film were successfully prepared on the surface of Q235 steel. By adjusting the preparation conditions, the NiFe-LDH-PFDTES film with optimal corrosion resistance was prepared in the condition containing the hydrothermal so-lution concentration is 1 unit and hydrothermal time for 6 h. The hydrophobicity changes little with the hy-drothermal parameters, and all reach the state of superhydrophobic, the contact angle is greater than 150 degrees, the sliding angle is less than 1 degrees. For the superhydrophobic film, NiFe-LDHs has excellent synergy with PFDTES, covering of an "air film" on the rough structure of LDHs, blocking the solution from contact with the substrate, thereby providing corrosion resistance. NiFe-LDH-PFDTES film exhibits much better corrosion protective performance than NiFe-LDHs film in 3.5 wt% NaCl solution, the impedance modulus is increased about 4-5 orders of magnitude compared with Q235 steel, and the highest protection efficiency can reach 99.99%.

Purpose The purpose of this paper is to identify corrosion types and corrosion transitions by a novel electrochemical noise analysis method based on Adaboost. Design/methodology/approach The corrosion behavior of Q235 steel was investigated in typical passivation, uniform corrosion and pitting solution by electrochemical noise. Nine feature parameters were extracted from the electrochemical noise data based on statistical analysis and shot noise theory. The feature parameters were analysis by Adaboost to train model and identify corrosion types. The trained Adaboost model was used to identify corrosion type transitions. Findings Adaboost algorithm can accurately identify the corrosion type, and the accuracy rate is 99.25%. The identification results of Adaboost for the corrosion type are consistent with corroded morphology analysis. Compared with other machine learning, Adaboost can identify corrosion types more accurately. For corrosion type transition, Adaboost can effectively identify the transition from passivation to uniform corrosion and from passivation to pitting corrosion consistent with corroded morphology analysis. Originality/value Adaboost is a suitable method for prediction of corrosion type and transitions. Adaboost can establish the classification model of metal corrosion, which can more conveniently and accurately explore the corrosion types. Adaboost provides important reference for corrosion prediction and protection.

The corrosion behavior of tinplate with different tensile strain in 0.1 mol/L NaCl solution was investigated by using polarization curve, electrochemical impedance spectroscopy (EIS) and immersion tests. The surface morphology of tinplate before and after immersion was observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM), and the content of iron ions dissolved in NaCl solution was determined by inductively coupled plasma mass spectrometer (ICP-MS). The experimental results showed that with the increasing of tensile strain the deformed tinplate has a lower thickness and a higher surface roughness, meanwhile the density of slip bands and defects on the tinplate is also increased. In NaCl solution, the deformed tinplate has a positive corrosion potential and a lower polarization resistance, and the corrosion current density and concentration of iron ions dissolved in solution are both raised with the increasing of tensile strain. Based on these results, the relationship between the corrosion rate and tensile strain of tinplate was built and discussed.

A novel self-healing composite coating was fabricated on magnesium alloy by using polycaprolactone (PCL) as resin matrix and iron-based metal-organic framework MIL-53 modified with tannic acid (TA) as function filler. The surface morphology, structure and wettability of composite coating were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) and sessile water droplet static contact angle. The corrosion resistance and healing performance of PCL coatings was determined by electrochemical impedance spectroscopy (EIS) and photothermal tests. Results indicate that MIL-53@TA/PCL coating possesses a flatter surface, a higher corrosion resistance and better photothermal effect than that of blank PCL coating and MIL-53/ PCL coating. Under the near-infrared (NIR) laser irradiation with the wave length of 808 nm, the scratched MIL-53@TA/PCL coating could be healed within 10 min because of the excellent photothermal conversion ability of MIL-53@TA component.

Hydroxyapatite (HA) bioactive film is a standard surface modification method for biodegradable Mg alloys. However, the corrosion resistance of HA film prepared before was mediocre, and the preparation process was complicated. In this study, hydroxyapatite film was prepared for the first time on layered double hydroxides (LDHs) coated Mg alloy by hydrothermal method. The structure and composition of LDHs and HA films were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrometer (EDS), Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The corrosion resistance and immersion behavior of the films in simulated body fluid (SBF) were investigated by using potentiodynamic polarization curve, electrochemical impedance spectroscopy (EIS) techniques. The effects of different pH and calcium to phosphorus molar ratios (Ca/P ratios) of HA hydrothermal solution were investigated. The experimental results show that HA films appear in petal-like, filamentous and flower-like. The corrosion resistance of the film first increases and then decreases with the pH from weak acid to alkaline. With the increase of the Ca/P ratio, the film is gradually denser, and the protective effect is enhanced. The immersion test results show that after 7 days of immersion, the impedance modulus of the composite film is about 5 × 103 Ω·cm2, which is ten times higher than the single LDHs film. The effects of the pH and Ca/P ratio of the HA hydrothermal solution on the preparation of HA film are simply explained by thermodynamic theory. The Mg-LDHs-HA composite film provide a corrosion protection barrier for Mg substrate and HA film is biologically active. The barrier effect and the mineralization behavior provide a better corrosion protection for Mg substrate.

ZnO@ZIF-8 films were prepared on Q235 steel surface through solvothermal reaction by pre-electrodepositing ZnO films and modified with stearic acid (SA). The surface morphology, elements content, crystal structure and chemical structure of films were studied by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The wettability of films was measured by water contact angle meter. The corrosion behavior of films was tested by Electrochemical tests. ZnO films show hexagonal nanotubular morphology, having the best compactness and corrosion resistance at deposition current density of 2.3 mA/cm2 with the protection efficiency of 90.11%. After solvothermal reaction, ZIF-8 grains are formed and clad ZnO nanotubes, forming a contact film to prevent corrosive ions attacking steel efficiently. ZnO@ZIF-8 films have the best compactness and corrosion resistance at Zn2+ concentration of 0.06 mol/L with the protection efficiency of 99.83%. But the corrosion resistance of ZnO@ZIF-8 film declines quickly for the water molecules can get inside the film and destroy the bond between ZIF-8 grains. Thus, SA was grafted to ZnO@ZIF-8 film to enhance its hydrophobicity. After SA modification, the protection efficiency reaches 99.99% and maintains at 95.29% after 14 days immersion in the solution of 3.5 wt.% NaCl.