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•Silica nanoparticles-covered graphene oxide (SiO2-GO) nanohybrids were synthesized.•Fine nanometric SiO2 particles (<20nm) covered the surface of GO sheets.•SiO2-GO nanohybrids ...significantly enhanced the barrier properties of epoxy coating.•SiO2-GO nanohybrids significantly enhanced GO dispersion in epoxy coating.
This study reports two facile routes for the synthesis and characterization of silica nanoparticles-decorated graphene oxide (SiO2-GO) nanohybrids by a two-step in-situ sol-gel process using a mixture of 3-Aminopropyl triethoxysilane and Tetraethylorthosilicate in water–alcohol solution. Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and thermal gravimetric analysis (TGA) were employed for the SiO2-GO nanohybrids characterization. Field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM) were employed to characterize the SiO2 nanoparticles precipitation on the surface of GO sheets. FT-IR, XPS, AFM, FE-SEM and TGA analyses revealed that fine nanometric SiO2 particles (<20nm) covered the surface of GO sheets. X-ray diffraction and FE-SEM analyses showed better dispersion of SiO2-GO nanohybrids in the epoxy coating than pure GO. The effect of SiO2-GO nanohybrids on the corrosion protection and barrier performance of the epoxy coating was investigated by electrochemical impedance spectroscopy (EIS). Results revealed that SiO2-GO nanohybrids significantly enhanced the barrier and corrosion protection properties of the epoxy coating. It was also shown that SiO2-GO nanohybrids significantly reduced the cathodic delamination rate of epoxy coating.
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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.
•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.
•The steel substrate was treated by a covalently modified amino functionalized graphene oxide (fGO) film.•Deposition of fGO film at the interface of steel and epoxy could effectively improve the ...adhesion strength and corrosion protection properties.•More stable and stronger interfacial bonds was obtained when treating the interface by fGO film.
This study introduces a novel surface treatment approach of steel substrate by covalent modification of graphene oxide (fGO) nanosheets with 3-aminopropyltriethoxysilane to improve the adhesion and corrosion protection properties of an epoxy coating. The effect of fGO film on the epoxy coating performance was studied by field-emission scanning electron microscopy (FE-SEM), X-Ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), Pull-off adhesion, salt spray and cathodic delamination tests. Results revealed that deposition of fGO film on steel surface can effectively improve the adhesion strength and corrosion protection properties and reduce the cathodic delamination rate of the epoxy coating.
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The reinforcement effect of graphene oxide nanosheets on the mechanical properties of an epoxy coating has been extensively studied. However, the effect of graphene oxide quantum dot ...(GOQD) as a new unique carbon based nanomaterial (with lateral dimension of 5–6nm and thickness of one carbon atom) on the mechanical properties of epoxy coating has not been reported and compared with GO yet. So this study aims at fabrication of a high-performance polymer composite with unique mechanical properties using GOQD nanosheets.
GO and GOQD were obtained through two different strategies of “top-down” synthesis from an expandable graphite by a modified Hummers' method and an easy “bottom-up” method by carbonizing citric acid, respectively. The morphology, size distribution, microstructure and chemistry of the GO and GOQD were compared by utilizing X-ray diffraction (XRD) analysis, atomic force microscopy (AFM), high resolution-transmission electron microscopy (HR-TEM), high resolution field-emission scanning electron microscopy (FE-SEM), thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS). Results obtained from these analyses confirmed successful synthesize of GOQD and GO nanosheets. The reinforcement effect of GO and GOQD nanosheets on the mechanical properties of the epoxy coating was studied by dynamic mechanical thermal analysis (DMTA) and tensile test. It was found that the GOQD could remarkably enhance the energy of break, Young's modulus, tensile stress and interfacial interactions compared to the neat epoxy and the one reinforced with GO nanosheets. GOQD improved the fracture toughness by factor of 175% and 700% compared to the GO/Epoxy and neat epoxy, respectively.
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In this study it has been aimed to enhance the thermal resistance of epoxy coating through incorporation of SiO2-GO nanohybrids. SiO2-GO nanohybrids were synthesized through one-step ...sol-gel route using a mixture of Tetraethylorthosilane (TEOS) and 3-Aminopropyl triethoxysilane (APTES) silanes. The SiO2-GO nanohybrids were prepared at various hydrolysis times of 24, 48 and 72h. Then 0.2wt.% of GO and SiO2-GO nanohybrids were separately incorporated into the epoxy coating. Results revealed that amino functionalized SiO2 nanoparticles with particle size around 20–30nm successfully synthesized on the basal plane of GO. Results showed significant improvement of dispersion and interfacial interactions between nanohybrids and epoxy composite arising from covalent bonding between the SiO2-GO and the epoxy matrix. It was found that the thermal resistance of SiO2-GO nanohybrids and SiO2-GO/Epoxy nanocomposite was noticeably higher than GO and epoxy matrix, respectively.
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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•Steel surface was treated by Ce and acid phosphoric solutions.•Ce treatment considerably enhanced the surface energy and produce nanoscale roughness.•Ce treated samples showed enhanced adhesion to ...FBE coating.•Ce treatment of steel significantly reduced the FBE cathodic delamination rate.•Ce treated sample showed enhanced corrosion resistance.
The effect of surface pre-treatment of pipe surface by green cerium compound and phosphoric acid solution on the fusion-bonded epoxy (FBE) coating performance was studied. The composition and surface morphology of the steel samples treated by acid and Ce solutions were characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), equipped with energy dispersive spectroscopy (EDS). Also, the surface free energy was evaluated on these samples through contact angle measurements. In addition, the effect of Ce and acid washing procedures on the adhesion properties and corrosion protection performance of the FBE was examined by pull-off, salt spray and electrochemical impedance spectroscopy (EIS) tests. Results showed that compared to acid washing, the chemical treatment by Ce solution noticeably increased the surface free energy of steel, improved the adhesion properties of FBE, decreased the cathodic delamination rate of FBE, and enhanced the coating corrosion resistance compared to the acid washed samples.
•An anti-corrosion system based on hybrid silane sol–gel coating was prepared.•The impact of hydrolysis time on the silane coatings performance was evaluated.•The influence of silane concentration on ...coatings performance was studied.•The corrosion protection performance was investigated by EIS and salt spray.•The mixture of 50% silanes with 24 h hydrolysis revealed good corrosion protection.
This study aims at studying the effect of silane hydrolysis time and concentration on the corrosion protection performance of an eco-friendly hybrid silane coating based on tetraethylorthosilicate (TEOS) and trimethoxymethylsilane (TMOMS) on mild steel substrate. By electrochemical impedance spectroscopy (EIS) and salt spray test the corrosion evaluations were done. Results of Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA) and water contact angle tests measurements revealed the effective impact of the hydrolysis time and silane concentration on the curing process of the coating. Results revealed that the mixture of 50% silanes (TEOS/ TMOMS: 50/50 w/w) hydrolyzed for 24 h resulted in the highest corrosion resistance. The enhancement in protective performance of the hybrid coating was connected to the better condensation reaction, denser Si–O–Si network formation and less hydrophilicity of the coating.
