Corrosion Protection Properties Research Articles

Amorphous/Graphitic carbon phase engineering of Corrosion-Resistant Fe@C Core-Shell nanowires for optimized dipole polarization and enhanced microwave absorption

The study of designing and developing ferromagnetic nanocomposites with both microwave absorption (MA) and corrosion protection properties through microscopic heterogeneous interfacial engineering and crystal phase engineering remains challenging. In this study, Fe@C core–shell nanowires (FCNWs) are obtained by magnetic field-controlled in situ reduction method and annealing process to de-regulate the carbon shell thickness and carbon morphology. The enhancement of Fe-C heterogeneous relative interfacial effects and dielectric/magnetic response is revealed using density functional theory and simulated electromagnetic field distribution, and the modulation of the amorphous carbon/graphitic carbon ratio achieves the enhancement of dipole polarization in the low-frequency region. The FCNWs absorber had a minimum reflection loss (RLmin) of −47.6 dB at a thickness of 4.9 mm, and the maximum effective absorption bandwidth (EABmax) was achieved at 5.5 mm up to 4.0 GHz. In addition, the shielding effect of the graphitic carbon shell on the corrosion medium and the addition of additional electron conduction pathways allow the FCNWs absorber to obtain smaller corrosion currents and larger polarization resistances compared to Fe nanowires. Thus, modulation of atomic-scale heterogeneous interfaces and crystal phases has great potential in modulating the dielectric response.

The role of PEG/glycerol ratio on the structure and corrosion protection properties of PU-silica coating

In this work, investigation was made of the effect of incorporation of polyethylene glycol (PEG) in glycerol-based PU-silica coatings, with the aim of enhance thermal, mechanical, and corrosion protection properties, and establish a comprehensive knowledge regarding the synthesis of novel hybrid PU coatings with variable PEG/glycerol molar ratio. Nuclear magnetic resonance (13C NMR) and Fourier transform infrared (FTIR) spectroscopy analyses showed the conjugation of the PEG to the PU structure by urethane bonds, with the samples prepared using a higher amount of PEG presenting a less rigid structural conformation. Small-angle X-ray scattering (SAXS) measurements demonstrated a correlation between the inorganic fractal dimensionality and the PEG amount. The increasing PEG content contributes to improve thermal stability, coating roughness, and scratch hardness, that achieves typical values of 230 °C, 115 nm and 6H, respectively. As an anticorrosive barrier for steel, the 1.5 μm thickness coating prepared with 75 % glycerol and 25 % PEG exhibits an impedance modulus exceeding 10 GΩ.cm2 over 28 days in contact with saline solution. This new PEG/glycerol-based PU-silica coating proves highly suitable functional features for anticorrosive applications, offering commendable thermal stability, low thickness, high scratch resistance, and impressive impedance.

Multifunctional superhydrophobic coatings with self-cleaning and anti-fouling properties for corrosion protection of metals

Superhydrophobic coatings have self-cleaning, antifouling, and anti-corrosion properties due to their unique surface properties, but their disadvantages such as poor durability, poor mechanical properties, and complicated preparation methods severely limit their practical applications. Here, superhydrophobic coatings with high abrasion resistance and long-lasting corrosion resistance were prepared by a simple spraying method using stearic acid-modified titanium dioxide nanoparticles (TiO2), polyphenylene sulfide (PPS) as the base material, and doped polyvinylidene difluoride (PVDF). The SA-TiO2 can provide low surface energy and rough structure, and the PPS itself has high mechanical strength and corrosion resistance properties. The PVDF doping can generate cross-linking inside the coating to improve the densification and mechanical strength of the coating, while the formation of irregular micrometer-sized protrusions can play a role in protecting the nano-surface. he synergistic effect of the various components results in an excellent mechanical stability of the coating, which remains superhydrophobic after a 400 cm sanding test. In addition, the coating has excellent corrosion resistance, and the electrochemical impedance spectroscopy (EIS) results show that the impedance modulus of the coating is as high as 21.99 kΩ·cm2. The coating has a hierarchical micro-nano structure, and shows excellent mechanical and corrosion resistance, which is of great potential for practical applications.

Effect of tensile cracks on the corrosion protection properties of anodic oxide films on 5083 Al alloy

Sulphuric Acid Anodic Oxide (AAO) film is a common method for corrosion protection of 5083 Al alloys, and cracks may occur in the AAO film due to stress damage. In this study, cracks in the AAO film on 5083 Al alloy were pre-prepared by mechanical tension, and the cracks on the corrosion protection property of AAO film were in-situ investigated by scanning electrochemical microscopy (SECM). The morphology and composition of the AAO film were measured by SEM, XRD and XPS. The results show that the corrosion protection performance of AAO film for 5083 Al alloy decreases with the increase of cracks, which is due to the fact that cracks can act as diffusion channels for corrosive media, resulting in serious corrosion reaction. SECM shows the local current at the cracks of the AAO film first increases and then decreases due to the cracks being gradually repaired by the deposited corrosion products (Al(OH)3, Al(OH)2Cl, and AlOOH). A repair mechanism of cracks in AAO film on 5083 Al alloys is revealed during the corrosion process.

Advancing corrosion protection in confined spaces: a solvent-free UV LED-curable coating for steel pipelines with enhanced barrier properties and harsh environment performance

AbstractThis study investigates a novel solvent-free, UV LED-curable coating as a robust corrosion protection solution for the inner surface of steel pipelines. The properties of the UV-cured film were characterized in terms of reactivity, thermomechanical properties, and adhesion to metal substrates. The coating was applied to the inside steel pipelines and cured using a patented UV LED lamp designed to fit in confined spaces. Finally, electrochemical impedance spectroscopy characterization and an accelerated cyclic electrochemical technique were performed on the coated pipes to study the corrosion protection properties of the coating, both with and without the addition of inorganic fillers. The results were compared to a commercially available thermally cured coating. It was found that the UV-cured coating confers high barrier properties, effectively preventing liquid penetration even under elevated temperature conditions. Furthermore, the corrosion protection performance in harsh environments was comparable to and, in some cases, higher than standard epoxy linings.

Synthesis and characterization of modified iron oxide hydrophobic corrosion-resistant pigment for aluminum alloy coating

A hydrophobic coating containing modified iron oxides was prepared for corrosion protection of aluminum alloy. The modified iron oxide particles were synthesized using the annealing method and the evaluation of the corrosion-resistant benefits of modified iron oxides as additive in the epoxy resin coating was conducted. The raw FeOOH phase can be transformed into the α-Fe2O3 phase by increasing the annealing temperature. The morphology, colors, and pore size of the modified iron oxide are controllably evolved via finely adjusting the annealing temperature, which is beneficial for the compatibility, dispersion, and stability with epoxy resin. Besides, modified α-Fe2O3 annealed at 700 °C exhibited elliptical morphology and good solubility in epoxy resin solvents to form a hydrophobic corrosion inhibition layer (TP700), which further improves the corrosion resistance. Findings of corrosion electrochemical measurements and salt spray test confirmed the existence of TP700 composite coating resulted in the best corrosion protective properties on aluminum alloy during the corrosion process with the minimum corrosion current of 7.75 × 10−10 A cm−2 and the maximum |Z|0.01Hz value of 1.80 × 108 Ω cm2, which both are about two orders of magnitude higher than the commercial Fe2O3. Our results suggest a new venue for preparing modified iron oxide pigment on the surface of aluminum alloy materials for enhanced anti-corrosion applications.

An investigation on the mechanical and corrosion protection properties of poly(arylene ether nitrile) reinforced epoxy coating

To follow the current industrial demand, epoxy coatings which feature extraordinary comprehensive properties have been considered as a versatile and promising thermosetting resin for application in various middle and high-end sectors of multitudinous industries. Regrettably, epoxy coatings possess the inherent shortcoming of poor durability to external force and deformation, severely restricting further introjection in various fields. Herein, this study employs poly(arylene ether nitrile) with bisphenol A structure (PENBA) as superior intensifying agent to ameliorate the toughness and corrosion resistance of brittle epoxy coatings. As a linear thermoplastic polymer with satisfying mechanical performances, PENBA serves as epoxy's energy-dissipating medium and forms a semi-interpenetrating polymer network (SIPN) with epoxy matrix, efficiently impeding epoxy's fracture and crack propagation. As a result, the tensile strength, elongation at break, impact strength, and flexural strength of PENBA-modified epoxy possess considerable increments of 214 %, 360 %, 148 %, and 295 % in sequence by contrast with the pristine epoxy. Meanwhile, according to the potentiodynamic polarization analysis, the PENBA with outstanding chemical resistance also significantly promoted the epoxy's corrosion resistance, endowing the epoxy coating with the most positive Ecorr and icorr of −0.453 V and 9.439 × 10−10 A/cm2 when PENBA reached 15 % (mass percent) at the end of entire soaking process.

Synthesis and evaluation of a novel pyridinyl thiazolidine derivative as an antioxidant and corrosion inhibitor for mild steel in acidic environments

A new synthesized (Z)-2-((3,5-dichloropyridin-2-yl)imino)thiazolidin-4-one (DICPT) was evaluated as an antioxidant and a corrosion inhibitor for mild steel (M.STL) in a 0.5 M HCl solution. The antioxidant activity of newly synthesized DICPT was screened using a DPPH assay, and the results showed that DICPT has good antioxidant activity. Electrochemical assessments were conducted utilizing potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS). A new compound, DICPT, was synthesized, and its chemical structure was established and validated through various spectroscopic techniques, including including infrared (FTIR), nuclear magnetic resonance (NMR), and mass spectroscopy. PDP measurements revealed DICPT to be a mixed-type inhibitor. Charge transfer resistance (Rct) increased when inhibitor concentrations increased, according to EIS tests. The inhibition efficiency (%I) showed a corresponding rise with increasing inhibitor concentration, peaking at approximately 94.2 % at 3 × 10−5 M. Langmuir’s adsorption isotherm was found to govern the preferred adsorption mode of DICPT molecules onto the metal surface. UV–visible spectra confirmed the chemical interaction between DICPT molecules and the M.STL surface. AFM investigation indicated the formation of a protective layer on the metal surface, shielding it from corrosive environmental factors. Quantum chemical calculations were compared to experimental results to learn more about how corrosion is stopped and how well it works. Our study demonstrates the innovation of DICPT as a dual-function compound, offering both antioxidant and corrosion protection properties. This research contributes to the development of effective corrosion inhibitors for industrial applications.

Development of fluorosilicon bivalve isocyanate microcapsules for multifunctional coatings with excellent self-repairing properties, enhanced hydrophobicity, and corrosion protection properties

This study first self-made TMP-IPDI tetramer, and then prepared a fluorine-modified silicon dioxide double shell isocyanate type self-healing microcapsule (CBS-X/TMP-IPDI@PU@F-SiO2) using TMP-IPDI tetramer, fluorescent agent 4,4-bis (2-disulfonic acid sodium styrene) biphenyl (CBS-X) as the core material, polyurethane (PU) as the single shell, and fluorine modified silicon dioxide (F-SiO2) as the double shell using interfacial polymerisation method. Then, it was added to waterborne polyurethane (WPU) to prepare self-healing coatings and coatings. The chemical structure, microstructure, self-healing self detection, and mechanical properties of TMP-IPDI, CBS-X/TMP-IPDI@PU@F-SiO2, and composite coatings were characterized by infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H NMR), scanning electron microscopy (SEM), particle size analysis (PSA), X-ray electron spectroscopy (XPS) analysis, contact angle testing, tensile testing, electrochemical impedance testing, and Ultraviolet photograph. The results showed that the TMP-IPDI tetramer was successfully prepared. The average particle size of CBS-X/TMP-IPDI@PU@F-SiO2 prepared is 29 μm. The contact angle, tensile strength, low-frequency impedance and Nyquist curve radius of the repaired spots increased with the increase of the amount of CBS-X/TMP-IPDI@PU@F-SiO2 in WPUs; the increasing trend slowed down when the amount of CBS-X/TMP-IPDI@PU@F-SiO2 was >5 %. When the CBS-X/TMP-IPDI@PU@F-SiO2 dosage is 5 %, the WPU coating has good self-repair and self-detection performance. The stress before and after repair were 12.89 MPa and 20.11 MPa, respectively, with a repair rate of 80.3 %. The contact angle at the repair site can reach 100.8°, and the coating has good corrosion resistance. The microcapsules prepared based on fluorine-modified silica (F-SiO2) as the wall material have good self-healing performance for WPU coatings, achieving secondary protection of the repaired material.

Green Synthesizing and Corrosion Inhibition Characteristics of Azo Compounds on Carbon Steel under Sweet Conditions: Experimental and Theoretical Approaches.

The deterioration of carbon steel in saline solutions enriched with carbon dioxide represents a significant challenge within the oil and gas industry. So, this study focuses on the design and structural analysis of four azo derivatives: 4-(2-quinolinylazo)-catechol (AZN-1), 4-(4-phenoxyphenylazo)-1-naphthol (AZN-2), 4-(4-pyridylazo)-1-naphthol (AZN-3), and 4-(2-pyridylazo)-1-naphthol (AZN-4), and their first application as effective corrosion inhibitors for carbon steel in a carbon dioxide saturated 3.5% sodium chloride solution. Spectroscopic methods were used to characterize the structural configurations of these compounds. The corrosion protection properties of these compounds on carbon steel in a carbon dioxide saturated 3.5% sodium chloride solution (under sweet conditions) were investigated using Tafel polarization (PDP), electrochemical impedance spectroscopy (EIS), and field emission-scanning electron microscopy (FE-SEM) studies. The results indicate that the inhibition efficiency increases as the concentration of the inhibitors increases. There is a notable agreement between the results obtained from the PDP and EIS measurements, supporting the findings. Moreover, the results displayed that these compounds had significant corrosion protection capabilities at low concentrations, ranging from 91.0 to 98.3% at an additive concentration of 5 × 10-4 M. The PDP profiles showed that these compounds acted as mixed inhibitors, and their adsorption behavior followed the Langmuir isotherm model. Besides, EIS results corroborate the adsorption of AZN compounds through a reduction in double-layer capacitance (Cdl) alongside an augmentation in polarization resistance (Rp) after the addition of AZN compounds into the corrosive solution. Field emission scanning electron microscopy (FE-SEM) and Fourier-transform infrared spectroscopy (FTIR) analysis confirmed the formation of a protective layer on the surface of carbon steel when these inhibitors were applied. In addition, computational calculations and Monte Carlo simulations were performed to support the experimental observations, gain insights into the adsorption properties, and elucidate the corrosion inhibition mechanisms of these compounds.

2D Nanomaterials Reinforced Organic Coatings for Marine Corrosion Protection: State of the Art, Challenges, and Future Prospectives.

2D nanomaterials, with extraordinary physical and chemical characteristics, have long been regarded as promising nanofillers in organic coatings for marine corrosion protection. The past decade has witnessed the high-speed progress of 2D nanomaterial-reinforced organic composite coatings, and plenty of breakthroughs have been achieved as yet. This review covers an in-depth and all-around outline of the up-to-date advances in 2D nanomaterial-modified organic coatings employed for the marine corrosion protection realm. Starting from a brief introduction to 2D nanomaterials, the preparation strategies and properties are illustrated. Subsequently, diverse protection models based on composite coatings for marine corrosion protection are also introduced, including physical barrier, self-healing, as well as cathodic protection, respectively. Furthermore, computational simulations and critical factors on the corrosion protection properties of composite coatings are clarified in detail. Finally, the remaining challenges and prospects for marine corrosion protection based on 2D nanomaterials reinforced organic coatings are highlighted.

The Inhibition Action of Some Brij-Type Nonionic Surfactants on the Corrosion of OLC 45 in Various Aggressive Environments.

The corrosion protection property of three Brij-type surfactants, namely, Brij 35, Brij 56 and Brij 58P, was considered on OLC 45 carbon steel in a 0.5 M H2SO4 medium. The efficacy for these organic compounds was examined using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods, scanning electron microscopy (SEM) procedures, and Fourier transform infrared (FT-IR) spectroscopy. We hypothesized that these surfactants hinder the corrosion for OLC 45 samples through a protecting mechanism owing to the adsorption of organic molecules that form an inhibitive film or through the formation of complex oxides. These surfactants exhibited an appreciable protective effect against OLC 45 corrosion, operating as mixed inhibitors, as could be demonstrated by their influence on the electrochemical characteristics of the metallic substrates. The adsorption of surfactants over the substrates zone conformed to the representation of the Langmuir isotherm. The effect of temperature on the electrochemical comportment of the OLC 45 specimens in H2SO4 without and with Brij at 800 ppm was examined in the temperature interval of 293 to 333 K. The negative estimate of thermodynamic attributed as Gibbs free energy of adsorption presented the spontaneity of the adsorption activity. The investigation with FT-IR and SEM established the adsorption of Brij and the constitution of the corrosive components on the OLC 45 surface. Electrochemical determinations of these surfactants indicated its anticorrosion inhibition performance and the highest inhibition of 96% was reached when the Brij 35 concentration was at 800 or 1000 ppm, while for Brij 56 and Brij 58P, the highest inhibition was obtained when their concentrations were 500, 800, or 1000 ppm.

High-efficiency graphene/epoxy composite coatings with outstanding thermal conductive and anti-corrosion performance

Although graphene is an ideal thermal conductive and anti-corrosion filler, the thermal conductivity and corrosion resistance of graphene/polymer composite coatings are difficult to improve synergistically. Herein, graphene (rGO) and benzotriazole-loaded hollow mesoporous silica (BTA@HMS) were mixed into epoxy to simultaneously improve its thermal conductivity and anti-corrosion performance. The results show that the thermal conductivity of the prepared rGO-BTA@HMS/epoxy composite coating reaches 1.239 W/(m·K), which is improved by 596 % over pure epoxy. The corrosion protection property of the composite coating is four orders of magnitude higher than that of pure epoxy. Furthermore, BTA@HMS can significantly inhibit the accelerated corrosion of the copper metal coated by rGO/epoxy composite coatings through its self-healing function, and the charge transfer resistance for substrate corrosion is increased from 60 KΩ·cm2 to 3410 KΩ·cm2 due to the introduction of BTA@HMS. The prepared composite coatings have the potential for applications in thermal conductive and anti-corrosion coating fields.

Epoxidized technical Kraft lignin as a particulate resin component for high-performance anticorrosive coatings

AbstractDeterioration of steel infrastructures is often caused by corrosive substances. In harsh conditions, the protection against corrosion is provided by high-performance coatings. The major challenge in this field is to find replacements for the fossil-based resins constituting anticorrosive coatings, due to increasing needs to synthesize new environmentally friendly materials. In this study, softwood Kraft lignin was epoxidized with the aim of obtaining a renewable resin for anticorrosive coatings. The reaction resulted in the formation of heterogeneous, solid, coarse agglomerates. Therefore, the synthetized lignin particles were mechanically ground and sieved to break up the agglomerates and obtain a fine powder. To reduce the use of fossil fuel-based epoxy novolac resins in commercial anticorrosive coatings, a series of formulations were prepared and cured on steel panels varying the content of epoxidized lignin resin. Epoxidized lignin-based coatings used in conjunction with conventional epoxy novolac resin demonstrated improved performance in terms of corrosion protection and adhesion properties, as measured by salt spray exposure and pull-off adhesion test, respectively. In addition, the importance of size fractionation for the homogeneity of the final coating formulations was highlighted. The findings from this study suggest a promising route to develop high-performing lignin-based anticorrosive coatings.

Effect of substrate microstructure on corrosion resistance of cast and forged anodised 6082 Al alloy

This work addresses the effect of the surface morphology of a 6082-aluminium alloy on the characteristics of the anodic layer generated by an anodising process using two current densities. The samples tested were horizontal direct chill (HDC), vertical direct chill (VDC) cast billets, and the same material after forged + T6 ageing treatment. Samples were anodised in a mixed citric acid‑sulphuric acid electrolyte using 0.5 A⋅dm−2 and 1.5 A⋅dm−2. D.C. current densities. The protective character of the oxide layer was studied by electrochemical impedance spectroscopy (EIS) in 0.1 M NaCl solution.Microstructural characterisation revealed that the microsegregation and forging processes have a significant effect on the growth of the oxide layer as well as on the optimum anodising conditions. The EIS study showed that the corrosion protection provided by the oxide layer on Al6082 alloy was strongly affected by the manufacturing process, with thinner oxide layers obtained for cast billets. Heat treatment and forging homogenise the microstructure, which positively affects anodising and modifies the growth rate and thickness of the oxide layer. This effect makes obtaining a thicker oxide layer with good corrosion protective properties possible by using lower current densities for forged samples.

A Comparative Study of the Corrosion Behavior of P110 Casing Steel in Simulated Concrete Liquid Containing Chloride and Annulus Fluid from an Oil Well

The corrosion behavior of P110 casing steel in simulated concrete liquid and simulated annulus fluid was investigated to reveal the corrosion pattern and protective properties of corrosion products in the two environments. Potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS), Mott–Schottky tests, and electrochemical noise (EN) tests were used to study the corrosion behavior of P110 casing steel in simulated concrete liquid and simulated annulus fluid saturated with CO2. Scanning electron microscopy (SEM) combined with Energy-Dispersive Spectrometer (EDS) mapping was used to characterize the corrosion morphology and elemental distribution of P110 casing steel. The results show that the corrosion resistance of P110 casing steel deteriorates with the increasing immersion days in the simulated annulus fluid, the impedance decreases gradually, and the corrosion-product film shows a loose and porous structure. In the simulated concrete liquid, under the condition of containing a low concentration of Cl−, the protection of the corrosion products gradually increases with the extension of immersion days. With the increasing concentration of Cl− and the extension of immersion days, the electrochemical noise resistance and charge transfer resistance of P110 steel decrease gradually, and the protective property of the corrosion-product film decreases, which is capable of forming steady pitting corrosion.

Electrodeposited graphene/layered double hydroxides micro/nanocontainers for both passive and active corrosion protection

The poor dispersibility of layered double hydroxides (LDHs) is considered to be the main drawback limiting their application in anti-corrosive coatings. In this work, the problem is solved by combining LDHs with graphene (Gr). A facile electrochemically assisted deposition technique (EAT) is developed to prepare Gr/LDH micro/nano-containers. The high-barrier Gr and LDHs synergistically build a ‘labyrinth effect’ to lengthen the diffusion path of corrosive mediums. Moreover, corrosion inhibitors can be released from the interlayer galleries of LDHs and impede corrosion of metal substrate by substituting the aggressive ions. Therefore, the polyvinyl butyral (PVB) coatings doped with Gr/LDH micro/nano-containers pre-loaded with inhibitors 2-Mercaptobenzothiazole (MBT) have both passive and active corrosion protection properties and provide excellent protection to copper substrate.

Improved corrosion resistance of AZ31B Mg alloy by eco-friendly flash-PEO coatings

The aim of this work was the preparation of an environmentally friendly protective coating on the AZ31B alloy using Flash plasma electrolytic oxidation (F-PEO) process. It was developed with different electrolyte compositions, that determine the morphology and properties of the coatings, this being crucial to understand the anti-corrosion properties. The incorporation of carbonate ions to the electrolyte proved to enhance the electrical response of the F-PEO process, resulting in a more efficient process with an energy reduced consumption of 1.1 kW h m−2μm−1. Surface and cross-sectional morphology analysis of the coatings revealed the presence of isolated pores structure with small pore size (less than 1 µm) that delays the infiltration of aggressive ions towards the substrate. The characterisation by XRD, EDX and Raman spectroscopy showed the presence of amorphous carbonate and phosphate phases in the FPEO-CO layer, that provide a self-restauration effect through a dissolution/reprecipitation mechanism. The lowest value of the corrosion current density was obtained for FPEO-CO coating, 4.60 × 10−7 A·cm−2, together with the highest impedance modulus (f<0.1 Hz), ⁓104 Ω·cm2, two orders of magnitude higher than the AZ31B Mg alloy. Furthermore, the corrosion protection properties of FPEO-CO coating were also analysed through an immersion test in 3.5 wt.% NaCl, confirming the excellent response of the coating for long times up to 336 h (2 weeks). The synergy between a more compact coating and the self-repairing ability of carbonate amorphous species plays a critical role in improving the corrosion resistance properties of the AZ31B Mg alloy, offering an eco-friendly alternative to chromate conversion coatings.

Waterborne epoxy coating with excellent barrier and self-healing properties for long-term corrosion protection

Herein, an intelligent anticorrosive coating with superior barrier and self-healing properties was prepared. Molybdate (MoO42−) intercalated layered double hydroxide (MIH) was synthesised and polydopamine (PDA) shell was grown on MIH surface to prepare MIH@PDA (PMIH) material. PMIH was assembled on graphene (Gr) sheet through π–π interaction to obtain the Gr@PMIH composite. The anticorrosive coating was prepared by incorporating Gr@PMIH into the epoxy resin. The PMIH material demonstrated a stimulus-response capacity due to the solubility of polydopamine in acidic conditions. In addition, the ion-exchange properties of the layered double hydroxide (LDH) facilitated the release of the encapsulated molybdate corrosion inhibitor between LDH layers and the adsorption of chloride ions. This mechanism was corroborated by ultraviolet–visible (UV–vis) spectroscopy results. Electrochemical impedance spectroscopy (EIS) results revealed that the incorporation of MIH and Gr@PMIH materials considerably enhanced the low-frequency (0.01 Hz) impedance modulus. Among the tested ratios, Gr@PMIH/waterborne epoxy coatings (WECs) (3:7) exhibited the most effectively long-term corrosion protection. EIS measurements of the scratched coatings confirm the superior corrosion resistance and inhibition properties of Gr@PMIH/WECs (3:7). Furthermore, after 400 h of salt spray testing, substrates coated with Gr@PMIH/WECs (3:7) showed the least amount of corrosion products and blisters around surface scratches, affirming its exceptional long-term corrosion protection performance. Thus, the excellent barrier and stimuli-responsive characteristics of the Gr@PMIH material endowed the coating with enhanced long-term corrosion resistance and intelligent protection capabilities.

Preparation of self-healing superhydrophobic polyacrylate coatings based on silica matrix-microcapsules containing corrosion inhibitor for long-term corrosion protection

In this study, a superhydrophobic coating with self-healing properties for carbon steel corrosion protection was developed, incorporating fluorinated silica microcapsules containing corrosion inhibitor and fluorinated siloxane acrylate copolymer (FSC). Triethanolamine (TEA), functioning as a corrosion inhibitor, was encapsulated in silica matrix-microcapsules through a water-in-oil (W/O) interfacial condensation method. Furthermore, the prepared silica microcapsules underwent 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES) fluorination modification under the catalytic action of ammonia. Upon mechanical disruption of the superhydrophobic coating, the microcapsules liberate rust inhibitors, thereby instigating the formation of a fresh passivation layer on the surface of mild steel, perpetuating its defense against corrosion. These prepared superhydrophobic coatings manifest commendable antifouling, self-cleaning, and durability attributes, collectively representing pivotal traits requisite for efficacious metal surface anticorrosion. Electrochemical impedance spectroscopy (EIS) assessments conclusively substantiate the pronounced enhancement in the corrosion resistance of mild steel surfaces upon application of the synthesized superhydrophobic coating. More importantly, the self-healing capability of the superhydrophobic rust-resistant coating has been confirmed through EIS testing. Specifically, following mechanical damage to the superhydrophobic coating, the corrosion resistance of specimens housing rust inhibitors markedly exceeds that of counterparts devoid of these inhibitors. The innovative amalgamation of intelligent composite superhydrophobic coatings, underscored by these findings, underscores its broad applicability in combating metal corrosion, thereby holding substantial promise in this domain.