•GO-PANIs/Epoxy nanocomposites were fabricated and analyzed.•GO-PANI composites improved the corrosion resistance of the epoxy coating.•GO-PANI I significantly improved the barrier/active performance ...of epoxy coating.
Graphene oxide nanosheets were functionalized with polyaniline (PANI) nanofibers through three methods In method II the polymerization of aniline was done in the presence of sodium dodecyl sulfate as a surfactant and ammonium persulfate as an initiator. In method I the surfactant and in method III the initiator were eliminated during polymerization procedure. The morphology and chemistry of the nanosheets were characterized. Then, the GO/epoxy and GO-PANIs/epoxy nanocomposites were fabricated and their corrosion protection performance was studied on steel substrate by electrochemical impedance spectroscopy. Results revealed that GO-PANI remarkably improved the barrier performance and provided active inhibition for epoxy coating.
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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.
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•Hybrid silane with different volume ratios of TEOS/APTES as intermediate layer.•Chemical bond between PEO coating and silane layer.•Covalent bond between silane layer and epoxy ...coating.•Best protective properties for coating systems with T50/A50 layer.•Increasing adhesion strength of epoxy coating with silane as intermediate layer.
In this study, a PEO/Silane/Epoxy three-layer coating was introduced as an effective protection system for the preservation of Mg alloy. Cerium nitrate was used as an inhibitor in the (plasma electrolytic oxidation) PEO coating structure and was coated with a silane layer containing various volume ratios of tetraethoxysilane (TEOS) and γ-amino propyltriethoxysilane (APTES). Electrochemical impedance spectroscopy (EIS) and adhesion tests were performed on three-layer coating samples. Protective properties of PEO coating as well as PEO/Epoxy coating was improved by applying the silane film as the interfacial layer, with the T50/A50 saline film showing the best protective performance.
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•The nanoceria-decorated cerium (III)-imidazole network (NC/CIN) was produced.•The NC/CIN-contained epoxy showed excellent barrier-inhibitive protection properties.•NC/CIN greatly ...reinforced the cross-linking density and toughness of epoxy coating.
For the first time, a novel metal-organic framework (MOF)-like nano-pigment was synthesized for fabrication of a high-performance epoxy composite material with excellent anti-corrosion and thermo-mechanical properties. The nanoceria-decorated cerium (III)-imidazole network (NC/CIN) as a new metal-organic network (MON) structure was produced by a one-pot co-precipitation route through covalent and/or coordinate networking of cerium (III) as metallic cation centers and 2-methylimidazole as organic linker in methanol medium. The NC/CIN structure was analyzed by UV–Visible spectroscopy (UV–Vis), Furrier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), Raman spectroscopy, X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), field emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDS) examinations. The characterization results revealed that the thermal-stable CIN hybrid product decorated by ceria nanocrystals (with average particle sizes below 51 nm) was produced via chemical bonding/networking of the cerium and imidazole precursors, resulting in only 0.047 cm3 g−1 pore free volume of the final networked product. Thermo-mechanical and anti-corrosion performance of the NC/CIN-incorporated epoxy composite were examined by tensile, dynamic mechanical thermal analysis (DMTA), electrochemical impedance spectroscopy (EIS) and salt spray evaluations. The results exhibited that the NC/CIN-contained epoxy composite provided remarkable barrier-inhibitive protection for mild steel in the corrosive environment (log |Z|10 mHz = 9.91 Ω cm2 after 7 weeks exposure of the intact coating to saline solution) as well as self-repairing protective properties in the artificial defected nanocomposite. Moreover, the great reinforcement in the cross-linking density (~40.8 mol cm−3, more than 4 times efficiency), ductility and toughness (~246 J, 4 times efficiency) features of the epoxy composite was explored.
•Zn-Al- layered double hydroxides were successfully doped with phosphate ions.•Phosphate loaded nanocontainers showed better inhibition effect than nitrate one and formed passive film on steel ...surface.•Silane film including Zn-Al-PO43− nanocontainer significantly reduced cathodic delamination of epoxy coating on steel.•The improvement of self-healing ability of the coatings loaded with Zn-Al-PO43− was much higher than Zn-Al-NO3−.
This study aims at synthesis and characterization of Zn-Al-PO43− and Zn-Al-NO3− layered double hydroxides (LDHs) through employing FE-SEM, EDS and X-ray photoelectron spectroscopy (XPS) analyses. The smart release ability of the inhibitive spices from LDHs were checked by EIS, polarization and surface analysis tests in 3.5wt.% NaCl solution. A two-layer coating system consisting of silane primer filled with LDHs and epoxy-polyamide top coat were applied on steel and then the active inhibition capability of the coatings was investigated. The addition of Zn-Al-PO43− LDH to the silane coating provides efficient inhibition behavior by releasing PO43− anions through ion exchange process.
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•Modification of GO by polyaniline nanofibers enhanced its electrical conductivity.•Barrier properties of zinc rich paint remarkably increased after addition of GO-PANI.•GO-PANI ...enhanced the electrical contact between zinc particles and steel substrate.•The zinc rich sacrificial behavior noticeably enhanced after addition of GO-PANI.
This study reports a new strategy for providing ZRC with enhanced cathodic and barrier protection mechanisms simultaneously. For this purpose, the graphene oxide (GO) nanosheets were modified by highly crystalline and conductive polyaniline (PANI) nanofibers in the form of Emeraldine salt (ES) through an in situ polymerization of aniline in the presence of GO as an oxidant. The aniline polymerization in the presence of GO and the PANI nanofibers deposition on the GO surface were exhibited by Fourier transform infrared (FT-IR) spectroscopy and high resolution-transmittance electron microscopy (HR-TEM). In addition to these the X-ray diffraction (XRD) patterns confirmed the deposition of highly crystalline PANI nanofibers on the GO and between the GO layers. Inclusion of 0.1wt% GO and GO-PANI nanosheets into the ZRC sample remarkably enhanced its corrosion protection performance. Salt spray, open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) measurements revealed that both the cathodic protection properties and barrier performance of the ZRC were improved after addition of 0.1wt% GO and GO-PANI nanosheets to the ZRC sample. The most pronounced improvement in the ZRC properties was obtained using GO-PANI. The results obtained from field-emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy and XRD analysis confirmed lower degree of zinc particles oxidation and steel substrate corrosion in the case of ZRC including GO-PANI nanosheets compared to other samples.
Surface modification of graphene oxide (GO) has been performed by grafting of polyisocyanate (PI) resin. Results obtained from X-ray photo electron spectroscopy, thermal gravimetric analysis and ...X-ray diffraction analysis revealed that the PI resin chains were successfully attached onto the surface of GO nanosheets through covalent bonding with hydroxyl and carboxylic groups leading to amides and carbamate esters bonds formation. Subsequently, the PI functionalized GO sheets were incorporated into the polyurethane (PU) matrix. The X-ray diffraction analysis showed that surface modification of GO nanosheets with PI enhanced the level of exfoliation of PI–GO in the PU matrix. Scanning electron microscope analysis showed the enhanced interaction between GO and PU matrix after functionalization by PI resin. The electrochemical impedance spectroscopy and salt spray tests were performed to reveal the effects of addition of 0.1wt.% GO and PI–GO nanosheets on the corrosion protection properties of the PU coating. Also, the adhesion loss of the coatings was obtained by pull-off adhesion test after 30days immersion in 3.5wt.% NaCl solution. It was found that incorporation of 0.1wt.% surface modified GO nanosheets into the PU matrix resulted in significant improvement of the coating corrosion protection properties and ionic resistance.
The Persian Liquorice was introduced as a sustainable corrosion inhibitor with excellent inhibition action for mild steel in sodium chloride solution. Persian Liquorice is a root of Glycyrrhiza ...glabra including many active compounds like Glycyrrhizin (GL), 18β- Glycyrrhetinic acid (GA), Liquritigenin (LTG), Licochalcone A (LCA), Licochalcone E (LCE), and Glabridin (GLD). The Fourier transform infrared (FT-IR) spectroscopy was utilized to track various active components exist in the Persian Liquorice extract. Electrochemical impedance spectroscopy, potentiodynamic polarization and electrochemical current noise measurements were conducted to investigate the corrosion inhibition role of various concentrations of Persian Liquorice extract toward mild steel corrosion in sodium chloride solutions. Surface analysis, molecular dynamics and quantum mechanics simulation methods were combined to get insights of inhibitor molecules adsorption on the mild steel surface. The electrochemical investigations revealed that in the presence of 600 ppm Persian Liquorice extract the maximum inhibition efficiency of 98.8% was obtained, which is connected to the build-up of a protecting layer over the mild steel surface, blocking the pathway of harsh ions diffusion. There is no report on use of any sustainable corrosion inhibitor for mild steel in chloride solution with this high level of inhibition power even after long immersion time (72 h). The formation of protecting layer on the mild steel surface was proved by scanning electron microscope and atomic force microscope results. The results derived from MD simulations and QM calculations revealed the adsorption of Persian Liquorice components on the steel substrate via donor-acceptor interactions.
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•Persian Liquorice was introduced as a green corrosion inhibitor for mild steel.•Electrochemical, surface characterization methods are used for inhibition study.•The Persian Liquorice extract behaves as a mixed-type inhibitor in NaCl solution.•Active species in inhibitor structure is responsible for its excellent performance.•Inhibition performance of inhibitor was explained by theoretical calculations.
This paper focuses on the synthesis and modification of graphene oxide nanosheets with polyaniline. The main aim is to take the advantages of both graphene oxide and polyaniline in enhancing the ...long-term performance (including weathering and corrosion) of exterior nanocomposites. For this purpose, the synthesized graphene oxide was treated via an in-situ polymerization process. The modified hybrid nanosheets were characterized by Fourier transform infrared spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FE-SEM), X-ray diffraction analysis (XRD), Ultraviolet–visible spectrophotometry (UV–Vis) and Raman spectroscopy. It was approved that the emeraldine base form of polyaniline has been successfully polymerized on the graphene oxide nanosheets in two forms of non-covalent bonding through π-π interactions between quinoid ring of PANI and basal plane of graphene oxide, and covalent bonding through reaction with epoxide group. The modified nanosheets were introduced into a typical epoxy matrix and then subjected to accelerated weathering and corrosion cycles. The results revealed that a considerable improvement in both weathering (42% reduction in ΔE) and corrosion resistance was achieved which was mainly attributed to the considerable enhancement in UV shielding, radical scavenging as well as better dispersion of graphene oxide modified with polyaniline.
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•An advanced anticorrosive inorganic/organic nanopigment based on praseodymium nitrate (PrN)/Urtica Dioica (UrDi) was synthesized and characterized.•The generation of chemical complex ...between PrN cations and UrDi functional groups was proved using various methods.•The PrN-UrDi hybrid green complex had significant inhibitive action for steel substrate in NaCl solution.
The main aim of this research is studying the corrosion inhibition properties of the combination of praseodymium nitrate (PrN) and Urtica Dioica (UrDi) on mild steel in sodium chloride solution. Fourier transform infrared (FT-IR), ultraviolet-visible (UV-Vis), thermogravimetric analysis/differential thermogravimetry (TGA/DTG) and X-ray photoelectron spectroscopy (XPS) results confirmed complex formation between Pr cations and UrDi (Pr-UrDi). Electrochemical results revealed that the Pr-UrDi hybrid complex had significant influence on the mild steel corrosion protection (by inhibition efficiency of ca. 94%) in NaCl solution.
