•Poly(o-phenylenediamine) are used to disperse graphene nanosheets in order to improve the compatibility between graphene and epoxy matrix.•The impedance modulus of 0.5∼1.0% G-Popd/EP is about ...1010 Ω cm2 during 60 days of immersion.•The corrosion of the substrate is retarded even if there is an artificial scratch to the G-Popd/EP.
In this research, soluble poly(o-phenylenediamine) nanoparticles were synthesized to noncovalently functionalize the graphene nanosheets via π-π interactions, and the corresponding protective performance of epoxy composite coatings was also investigated. Results showed that the impedance modulus of the composite coatings incorporated with 0.5–1.0% G-Popd was about 1010 Ω cm2 after 60 days of immersion. Furthermore, the corrosion of substrate was still retarded even if there is an artificial scratch to the composite coatings. The superior protective performance of the composite coating derived from the synergistic action in the barrier property of graphene nanosheets and metal surface passivation by Popd nanoparticles.
Two-dimensional Ti3C2Tx has demonstrated great potential for enhancing the protection performance of epoxy coating, but randomly-arranged Ti3C2Tx fails to meet higher expectations on the ...anti-corrosion/wear under extreme conditions. Here, the positively-charged Ti3C2Tx (f+-Ti3C2Tx) flakes obtained by functionalization and protonation were directionally distributed in the epoxy coating using an electrophoretic deposition method. The migration/rotation of f+-Ti3C2Tx flakes under electric field force and their mutual repulsion are responsible for the parallel alignment with the horizontal direction of coating. In particular, the epoxy coating incorporated with 1 wt % f+-Ti3C2Tx exhibits a near-perfect internal arrangement structure. When exposed to saline solution for the long period, its water absorption is decreased by 85.33% and the lowest-frequency impedance is increased by four orders of magnitude compared with randomly-arranged Ti3C2Tx hybrid epoxy coating, because parallelly-arranged f+-Ti3C2Tx with orientation factor can maximize the internal tortuosity and optimize the barrier properties of epoxy coating against aggressive ions. Furthermore, a significant friction reduction and an order of magnitude reduction in wear rate are obtained, mainly based on the increase of the deflection and branching of cracks in the friction process thus decreasing the probability of coating exfoliation. Therefore, the directional alignment of Ti3C2Tx in the epoxy coating can immediately upraise the protection properties’ ceiling, specifically suitable for long-term anti-corrosion/wear applications.
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•The positively charged f+-Ti3C2Tx is successfully arranged in parallel by electric field action.•The physical barrier network with the largest tortuosity formed by the parallelly-arranged f+-Ti3C2Tx array significantly inhibits the penetration rate of corrosive ions.•The horizontal regular arrangement of f+-Ti3C2Tx increases deflection and branching of cracks during defect growth, and thus reducing coating exfoliation.•This work raises the anti-corrosion/wear ceiling of Ti3C2Tx-based epoxy coatings, and the facile preparation process is conducive to large-scale practical applications.
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•PEO/Silane containing inhibitors as pretreatment of epoxy layer.•Studying active corrosion protection of inhibitors by EIS and EN tests.•Best protective properties for three-layer ...coating with Ce and 8-HQ inhibitors.•Improvement of wet adhesion strength of three-layer coating with Ce and 8-HQ.
PEO/Silane/Epoxy coating system with inorganic inhibitor (Ce(NO3)3) in the plasma electrolytic oxidation (PEO) layer as well as organic inhibitors in the silane layer was investigated in terms of active corrosion protection properties and adhesion strength. The results of electrochemical impedance spectroscopy (EIS), electrochemical noise (EN) and pull-off tests indicated that the presence of the 8-Hydroxyquinoline (8-HQ) organic inhibitor provides the optimal performance for coating systems. The formation of Ce(OH)3 in the PEO coating structure and the complex chelate of Mg(HQ)2 in the silane layer lead to the creation of active corrosion protection properties for the coating systems.
Surface charge accumulation on silicon carbide (SiC)/epoxy coatings with different contents of SiC filler, 3, 5, 7, and 10 wt%, is investigated using flat samples of epoxy substrate. In the ...experiments, a pair of finger-shaped electrodes was attached to the sample's surface using direct pressing and conductive adhesive providing two different types of contacts and, respectively, surface charging methods. The electrodes were energized by applying dc voltage for various time intervals and resulted surface charge distributions between the electrodes were measured. It was found that depending on the contact type, charging duration, and filler content, different patterns of homocharge or heterocharge appeared on the material surface. Physical reasons for the observed effects are analyzed based on the calculated electric field distributions in the experimental setup, results of the auxiliary tests on material charging in a limited air volume, and surface trap energy distributions measured by utilizing the isothermal surface potential decay (ISPD) method. Application of SiC/epoxy coating for controlling surface charge accumulation is discussed.
•Dopamine was grafted on the surface of the MOF-5 and a new type of Dopamine-Metal Organic Frameworks (DA-MOFs) was synthesized.•DA-MOFs can greatly enhance the barrier properties of the ...coatings.•DA-MOFs can enhance the coating of the cross-linked density.
In this study, dopamine (DA) was grafted on the surface of the Metal-Organic Frameworks (MOFs) and DA-MOFs were incorporated into waterborne epoxy coatings. The DA-MOFs were characterized using infrared spectroscopy, Thermogravimetric Analysis (TG), and X-ray diffraction (XRD). The coating properties was studied by using electrochemical impedance spectroscopy(EIS), salt spray test and adhesion test. Compared with epoxy resin coatings, coatings with DA-MOFs enhanced the properties of water resistance and corrosion resistance. The EIS results showed that the resistance value of coating with DA-MOFs was above 3.18×108Ωcm2. Corrosion protection performance of epoxy coating with 0.5wt% DA-MOFs was higher than others.
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•ZIF-8 was used as a multifunctional gatekeeper for HMSN-BTA.•HMSN-BTA@ZIF-8 was well-dispersed in epoxy matrix.•HMSN-BTA@ZIF-8 notably improved anticorrosion performance for epoxy ...coating.•HMSN-BTA@ZIF-8/epoxy coatings exhibited excellent self-healing performance.
Zeolitic imidazole framework-8 (ZIF-8) with porous structure, pH-response and facile synthesis characteristics, as a molecule delivery and stimulus-response nanomaterial, has been widely investigated over the past decades. Here, we report for the first time a new corrosion inhibitor-encapsulated nanocontainer (denoted as HMSN-BTA@ZIF-8), successfully synthesized using ZIF-8 as self-sacrificial template, pH-responsive gatekeeper and interfacial compatibility assistant for hollow mesoporous silica nanoparticle (HMSN). Corrosion inhibitors of benzotriazole (BTA) are encapsulated in the cavity and mesopores of HMSN. The results demonstrate that there are outstanding pH-triggered activities to both acidic and alkaline conditions for HMSN-BTA@ZIF-8. Rather than physically dispersing nanocontainers in the coating matrix, the synthesized HMSN-BTA@ZIF-8 can covalently interact with epoxy resin, resulting in superior compatibility and more uniform dispersion behavior of nanocontainers in the coatings. Interestingly, the epoxy composite coating with HMSN-BTA@ZIF-8 exhibits excellent corrosion protection and outstanding self-healing performances, which are well characterized by potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS), salt spray test and Scanning Kelvin Probe (SKP) technique. The outstanding anticorrosion and impressive self-healing properties are attributed to the good compatibility of HMSN-BTA@ZIF-8, the hydrophobicity of ZIF-8, higher crosslinking densities, and the controllable release of BTA in the epoxy composite coating. It is believed that this work is very helpful for extending the service life of various anticorrosion coatings.
This study reports an eco-friendly waterborne epoxy (WBE) coating with excellent corrosion resistance by adding ammonium grafted graphene oxide (AGO) as co-dispersant. AGO, as a co-dispersant, ...addresses the problem of a lot of micro-defects caused by the intrinsic mismatch between epoxy resin and amine curing agents during the formation of aqueous epoxy resin. Also, the compatibility of GO in the epoxy resin matrix is also improved by the ammonium modification. The ammonium modification process was systematically studied using Fourier transform infrared (FT-IR) spectra, X-ray diffraction (XRD) spectra, UV–vis spectra, Raman spectra and X-ray photoelectron spectra (XPS). Scanning electron microscope (SEM) images show that AGO sheets has successfully inhibited the formation of micro-pores and micro-defects, forming a more compact WBE/AGO composite coating. As a result, the corrosion resistance of the coating has been greatly improved as investigated by the potentiodynamic polarization test. The corrosion rate of WBE/AGO is decreased by three orders of magnitude compared to pure WBE coating. The corrosion protection mechanism of the WBE/AGO coating is studied via Electrochemical impedance spectroscopy (EIS) test, and equivalent electrical circuits are applied to fitting the EIS results and reveal the effect of AGO in the composite coating.
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•Ammonium-grafted graphene oxide (AGO) perfects WBE coatings curing process.•Ammonium ions improve dispersibility of GO effectively in epoxy matrix.•AGO enhances corrosion resistance of WBE coating by three orders of magnitude.
A nano-structured hybrid compound was fabricated with excellent corrosion inhibitor encapsulating capacity and the ability of controlled delivery of benzotriazole (BTA) for simultaneous enhancement ...of the hydrophobic property and corrosion resistance of epoxy coatings. The Ce-metal organic frameworks (Ce-MOF) were synthesized and served as nanocontainers, tetraethyl orthosilicate (TEOS) was further added to form a film to wrap Ce-metal organic frameworks. The addition of benzotriazole into nanocontainers endowed coating system with excellent anti-corrosion performance. The novelty lies in that the tetraethyl orthosilicate membrane would break and produce pores to release benzotriazole uniformly under acid condition, which was a pH-controlled self-healing process through polymer coatings providing an effective release of corrosion inhibitor. The fabricated hybrid compounds were comprehensively characterized with Fourier Transform infrared spectroscopy (FTIR), Ultraviolet–visible spectroscopy (UV-vis), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Electrochemical Impedance Spectroscopy (EIS) was performed to characterize the corrosion behavior of various composite coatings. Results indicated that the 3 wt.%Ce-metal organic frameworks incorporated into the epoxy coatings showed the most excellent anti-corrosion property.
Corrosion of aluminum and its alloys causes serious problems to our daily life. As a common method for corrosion protection, epoxy resin has been widely used as the coating material due to its easy ...processability and excellent properties. However, its high water absorption and brittleness, as well as the usage of volatile organic solvents during coating preparation, has limited its applications in some areas. In this study, we reported an environmentally friendly hydrophobic coating based on bio-epoxy using water as the only solvent during the preparation. The coating was fabricated by introducing superhydrophobic SiO2 nanoparticles, a hydrophobic curing agent, and hexadecyltrimethoxysilane into an isosorbide-based epoxy resin via a one-step spin coating process. The coating exhibits high hydrophobicity with a water contact angle (CA) of 134 ± 3°. This as-prepared coating is found to have good mechanical robustness against sands erosion: it maintained a high water repellence with the CA of 146 ± 2° after sands erosion for 30 s. In addition, the as-obtained coating shows a one-order of magnitude reduction in the corrosion current density (Jcorr), a positive shift of the corrosion potential (Ecorr) from −1.008 V to −0.747 V, and an inhibition efficiency of 92%.
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•Hydrophobic bio-based epoxy coating was prepared using water as the only solvent.•The hydrophobicity was highly improved with addition of nanoparticles.•The coating can maintain high water repellence even after sands erosion.•The as-prepared coating shows much improved corrosion resistance for aluminum.
In this article, long‐lasting anti‐corrosion graphene/epoxy coatings were successfully prepared using quinacridone as dispersant by solution mixing method. The results showed that quinacridone and ...graphene can form π–π bonds and improve the dispersibility of each other in epoxy coatings. Mechanical and anti‐corrosion properties of epoxy coatings with different contents of quinacridone and graphene have been tested, the results showed that the optimum weight ratio of graphene to quinacridone was 2:5. The tensile strength of the epoxy coatings with 0.2 wt% graphene and 0.5 wt% quinacridone reached 8.12 MPa, which was 1.44 times of the pure epoxy coatings. Moreover, the impedance modulus of the coatings reinforced with quinacridone and graphene was greater than 1011 Ω·cm2 after being immersed in 3.5 wt% NaCl solution for 140 days, which was two orders of magnitude higher than that of the pure epoxy coatings. We found that the reason for the improved performance of the epoxy coatings was not only that quinacridone improved the dispersibility of graphene in the coatings, but also more importantly, quinacridone adsorbed on the surface of graphene to form scale‐like crystalline structures, which enables graphene to reduce folds and wrinkles, thus giving full play to the shielding effect of graphene against corrosion factors.
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