Anticorrosion Performance Research Articles

Partially Bio-Based Benzoxazine Monomers Derived from Thymol: Photoluminescent Properties, Polymerization Characteristics, Hydrophobic Coating Investigations, and Anticorrosion Studies.

In this work, four thymol-based benzoxazines were synthesized using four primary amines with different chain lengths, namely methylamine, ethylamine, 1-propylamine, and 1-butylamine, which are then named T-m, T-e, T-p, and T-b, respectively. The optical properties of the synthesized thymol-based benzoxazines were examined via the photoluminescent study of their solutions in acetone. The results show that all the prepared benzoxazines emitted blue light with the maximum wavelengths from 425 to 450 nm when irradiated by the excitation wavelengths from 275 to 315 nm. The maximum excitation wavelengths are found to be 275 nm. The polymerization of the thymol-based benzoxazines is triggered by heat treatments with different conditions (160, 180, and 200 °C for 1 h). According to the FTIR results, the heat-curing process introduces a presence of the OH peak, of which intensity increases as the curing temperature increases. Thermal decompositions of thymol-based benzoxazines regarding TGA analyses reveal the enhancement of thermal stability of the benzoxazines with respect to the N-substituent chain length, as significantly observed the change in the first thermal decomposition at temperature ranged from 253 to 260 °C. Synthesized benzoxazine derivatives are further employed to coat the substrate, e.g., the glass slides. The investigation of the water contact angle shows that the coating of the benzoxazines onto the surface improves the hydrophobicity of the substrate, resulting in the enlargement of the contact angle from 25.5° to 93.3°. Moreover, the anticorrosion performance of the polybenzoxazine coatings is examined using potentiodynamic polarization techniques. The results illustrate the anticorrosion efficiency of the thymol-based polybenzoxazine up to 99.99%. Both hydrophobic and electrochemical studies suggest the feasibility for employing benzoxazines in anticorrosion coating applications.

Multifunctional polyurethane-based coating with corrosion resistance and anti-icing performance for AA2024-T3 alloy protection

In this study, we present the development of advanced anticorrosive icephobic coatings tailored for AA2024-T3 surfaces. These coatings were engineered using polyurethane, incorporating fluoropolyol and isocyanate modified with hydroxyl-terminated silicone oil and fluoroalkyl polyhedral oligomeric silsesquioxane (F-POSS) particles. Surface characterization involved contact angle and sliding angle measurements, as well as atomic force microscopy. The icephobic efficacy was evaluated through a battery of tests including differential scanning calorimetry, delay of freezing time measurement, impact and non-impact ice adhesion measurement (push-off and centrifuge), and the ice accretion method. Electrochemical impedance spectroscopy served to evaluate the anticorrosion performance of the coatings. The integration of silicone oil and F-POSS led to notable improvements in contact angles, increasing from 92° to 127°. The lowest sliding angle (6°) was obtained for the coating containing both silicone oil and F-POSS. Topographical images showed the essential role of F-POSS in providing a rough surface structure. The optimal coating formulation consisted of 10 wt% F-POSS particles and 5 wt% silicone oil, resulting in a water contact angle of 127°, a sliding angle of 9°, approximately 42 days of surface protection, and an impedance value of 4.8 × 108 Ω·cm2. Remarkably, this coating demonstrated exceptional durability in terms of icephobic properties, maintaining a push-off ice adhesion strength of 9.3 kPa even after 15 icing/de-icing cycles, confirming its desirable icephobic performance.

Construction of BTA-inbuilt ZIF-8 coated with molybdate-intercalated ZnAl-LDH as core-shell structured nanocontainers toward pH-responsive smart corrosion protection of waterborne epoxy coating

Nanocontainers encapsulating corrosion inhibitors are commonly incorporated into organic coatings to enable self-healing effects, thereby ensuring long-term anticorrosion performance. In this study, a novel dual corrosion inhibitor-loaded self-healing nanocontainer with core-shell structure was proposed for fabricating composite waterborne epoxy coatings with both active and passive corrosion prevention properties.The nanocontainer, named BTA-ZIF-8@LDH-Mo, was synthesized through the in-situ growth of molybdate-intercalated ZnAl layered double hydroxide (LDH-Mo) on the surface of 1H-benzotriazole-inbuilt zeolitic imidazolate framework (BTA-ZIF-8). Potentiodynamic polarization results showed that the Icorr of bare Q235 carbon steel immersed in a 3.5 wt% NaCl solution decreased from 4.658 × 10−6 A/cm2 to 1.274 × 10−6 A/cm2 after introducing BTA-ZIF-8@LDH-Mo nanocontainers, resulting in a superior corrosion inhibition efficiency of 72.65 %. Electrochemical impedance spectroscopy further demonstrated that the |Z|f=0.01Hz of epoxy coating doped with BTA-ZIF-8@LDH-Mo reached 4.24 × 109 Ω·cm2 after 42 d of immersion in 3.5 wt% NaCl solution, approximately 30 times higher than that of pure EP coating. Moreover, investigations on artificially scratched coatings indicated that the incorporation of BTA-ZIF-8@LDH-Mo nanocontainers effectively mitigated the corrosion process by forming an inhibiting layer on the metal substrate that impeded the corrosion process. The dual corrosion inhibitor strategy relies on the synergistic action of BTA pre-loaded in ZIF-8 nanoparticles and molybdate (MoO42-) intercalated in LDH interlayers for active corrosion protection. Additionally, the nanocontainers enhance passive protection by elongating the diffusion paths of corrosive media and trapping chloride ions. This nanocontainer design offers a facile strategy for fabricating a smart coating with the excellent anticorrosion properties.

Structure–property relationships of cationic polyurethane surfactants: Impact on surface activity and anticorrosion performance

Three cationic polyurethane surfactants (LC1–1, LC2–2, and LC2–3), each featuring different hydrophobic structures, were synthesized using isophorone diisocyanate, N-methyl diethanolamine, 1-bromohexadecane, and 1-bromobutane. The synthesized cationic polyurethane surfactants exhibited low surface tension, excellent foaming properties, and resistance to salt, attributed to steric hindrance among long-chain alkyl groups and their “multi-point anchoring” ability. The corrosion inhibition performance of polyurethane surfactants on carbon steel in 1 M HCl solution was evalutated, and LC2–2 showing a considerable corrosion inhibition efficiency of 97.0 %. This film effectively reduced/isolated contact between the corrosive solution and the steel interface. Furthermore, quantum chemical calculations corroborated the electrochemistry experiment results, affirming that the molecular structure of LC2–2 is particularly conducive to inhibiting the corrosion of carbon steel. This study explores the relationship between the molecular structure of surfactants and its impact on both surface activity and corrosion inhibition efficiency.

Fouling and Corrosion Behavior of Nickel–Graphene/Polytetrafluoroethylene Composite Hydrophobic Coating

Fouling and corrosion mitigation in heat exchange equipment remains a significant challenge. Numerous research techniques have been developed to address this issue. Surface modification is an effective method for preventing fouling and corrosion. This work used electrodeposition and dip coating techniques to create a nickel–graphene/polytetrafluoroethylene (NGP) composite hydrophobic coating. The field emission scanning electron microscopy, contact angle analyzer, X-ray photoelectron spectroscopy, energy dispersive spectroscopy, and atomic force microscopy techniques were used to investigate the surface morphologies, wettability, binding energies, chemical compositions, and roughness, respectively. The water contact angle (WCA) of the NGP hydrophobic coating (147.1° ± 2.2°) was significantly higher than the WCA of carbon steel (76.8° ± 1.6°). Electrochemical impendence spectroscopy results showed that the NGP composite hydrophobic coating has improved anti-corrosion performance with a greater capacitive curve, a higher modulus of impedance value at low frequency, and increased charge transfer resistance. Furthermore, fouling testing at various temperatures exhibited the anti-fouling and anti-corrosion behavior of the NGP composite hydrophobic coating, suggesting possible uses in practical applications.

A fluorine-free and high-robustness photothermal self-healing superhydrophobic coating with long-term anticorrosion and antibacterial performances

Superhydrophobic surface is a promising strategy for antibacterial and corrosion protection. However, the use of harmful fluorine-containing materials, poor mechano-chemical stability, the addition of fungicides and poor corrosion resistance often limit its practical application. In this paper, a high-robustness photothermal self-healing superhydrophobic coating is prepared by simply spraying a mixture of hydrophobically modified epoxy resin and two kinds of modified nanofillers (carbon nanotubes and SiO2) for long-term anticorrosion and antibacterial applications. Multi-scale network and lubrication structures formed by cross-linking of modified carbon nanotubes and repeatable roughness endow coating with high robustness, so that the coating maintains superhydrophobicity even after 100 Taber abrasion cycles, 20 m sandpaper abrasion and 100 tape peeling cycles. The synergistic effect of antibacterial adhesion and photothermal bactericidal activity endows coating with excellent antibacterial efficiency, which against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) separately reaches 99.6% and 99.8%. Moreover, the influence of modified epoxy resin, superhydrophobicity, organic coating and coating thicknesses on the anticorrosion of magnesium (Mg) alloy is systematically studied and analyzed. More importantly, the prepared coating still exhibits excellent self-cleaning, anticorrosion and antibacterial abilities after 20 m abrasion. Furthermore, the coating exhibits excellent adhesion (level 4B), chemical stability, UV radiation resistance, high-low temperature alternation resistance, stable heat production capacity and photothermal self-healing ability. All these excellent performances can promote its application in a wider range of fields.

Anti-corrosion performance of ethyl dimethyl propylammonium bis (trifluoromethyl sulfonyl) imide (EDMPA-TFSI) for AA3003 alloy in acid chloride solutions in the presence and absence of potassium iodide

This work aims to evaluate the anti-corrosion potential of ethyl dimethyl propylammonium bis (trifluoromethyl sulfonyl) imide (EDMPA-TFSI)-ionic liquid on AA3003 alloy in 0.5 M HCl solution in the presence and absence of potassium iodide at ambient and elevated temperatures. The corrosion inhibition of AA3003 alloy by EDMPA-TFSI in the presence of potassium iodide was evaluated using hydrogen evolution measurements at 303 K and 333 K. The results show that in the absence of potassium iodide, EDMPA-TFSI decelerates AA3003 corrosion in an acidic medium with a maximum inhibition efficiency of 93.2 % and 90.5 % obtained at 303 K and 333 K respectively. In the presence of potassium iodide, 94.7 % and 89.8 % inhibition efficiencies were obtained at 303 K and 333 K, respectively. This adsorption behavior is concordant with the Langmuir adsorption isotherm and the corrosion process in the presence of EDMPA-TFSI shows consistency with first-order reaction kinetics. New information on the application of EDMPA-TFSI as a workable corrosion inhibitor is provided herein.

Superhydrophobic-based corrosion mitigation systems and their effectiveness on dissimilar and similar friction stir spot-weld joint aerospace alloys

Traditional rivets have been a longstanding choice for securing aircraft components as permanent fasteners. A new technique called friction stir spot welding (FSSW) is gaining popularity as a rivet replacement. Despite its advantages, dissimilar FSSW joints are susceptible to corrosion, which can lead to property degradation. This study explored the potential of superhydrophobic (SH) coating as a corrosion inhibitor for FSSW joint aerospace alloys, particularly aluminum alloy (AA). The study involved a comparison of the corrosion resistance between SH-coated dissimilar (AA2024-T3 and AA7075-T6) and similar (AA2024-T3 and AA2024-T3) FSSW joint specimens. Notably, SH-coated dissimilar FSSW joint specimens demonstrated an exceptional average water contact angle (WCA) of 156°, confirming their SH nature. The study further incorporated the design of experiments (DOE) and statistical analysis to optimize constituent parameters and enhance the performance of SH coating. Durability testing indicated that SH-coated dissimilar FSSW joint specimens exhibited high resistance to acetone without influencing the WCA of 148°. Only a slight decrease in the WCA was observed when specimens were submerged in an acidic solution, where the WCA reduced to 142° from the original WCA of 158°. Also, specimens were stable and maintained the WCA of 154° when heat-treated at the temperature of 230 ℃. Moreover, a cross-cut adhesion test revealed that less than 5 % of the coating material was lost in SH-coated dissimilar FSSW joint specimens. Additionally, the electrochemical study evaluated the anti-corrosion performance of SH-coated dissimilar FSSW joint specimens, where the specimens were immersed for 6 days in 3.5 wt% NaCl solution. After 6 days in 3.5 wt% NaCl solution, specimens remained very close to SH, maintaining the WCA above 140°. Also, the electrochemical results demonstrated that the anti-corrosion performance of the SH-coated dissimilar FSSW joint specimens was enhanced with a lower corrosion rate of 37.56 mpy and current density of 0.428 µA/cm² as compared to the uncoated specimens. The variations in corrosion rates and current densities of the SH-coated dissimilar and similar FSSW joint specimens were very minimal, which proves that the application of SH coating on the FSSW joint specimens is suitable to alleviate corrosion-related problems in FSSW joints.

Regulating the structure and performance of amorphous carbon-based films by introducing different interlayers for applications in PEMFC bipolar plates

In this work, the effects of inserting an interlayer on the anti-corrosion performance of amorphous carbon (a-C) films in a simulated Proton Exchange Membrane Fuel Cell (PEMFC) environment have been systematically studied. Four a-C films with different interlayers, namely CCr, C-Cr-N, CrN and Cr, were prepared on 316L stainless steel substrates using unbalanced magnetron sputtering. The surface/fractural morphologies, carbon bonding structure and the anti-corrosion performance of the 4 films were observed/characterized in detail. The nanostructure and composition evolution from the film surface down to the film-substrate interface before and after electrochemical tests were also analysed via high resolution transmission electron microscopy (HRTEM). Results indicate that a-C films with CCr and C-Cr-N interlayers display superior corrosion resistance compared to undoped samples and those lacking an interlayer, with the lowest self-corrosion current density (i.e. 2.1 × 10−7 A/cm2, C-Cr-N interlayer) being nearly two orders of magnitude lower than that of the substrate (i.e. 1.1 × 10−5 A/cm2). The doped C-Cr-N interlayer plays a vital role in the corrosion resistance of the samples by accelerating oxidation of surface defect locations, inhibiting the continuous penetration of electrolyte, and improving corrosion resistance. Additionally, a-C films with a C-Cr-N interlayer exhibited an outstanding interface contact resistance (ICR) value (~3.5 mΩ/cm2) than that with a CrN interlayer (~30 mΩ/cm2) or the 316L substrate (~100 mΩ/cm2) at a typical contact pressure of 1.5 MPa. All 4 films demonstrate obviously improved hydrophobicity (contact angles against distilled water under room temperature up to 94.2°) compared to the substrate (75.8° under identical condition). In a word, this study proves that the strategy of inserting an appropriately designed interlayer (with the ternary C-Cr-N being most promising) to a-C films could alter and enhance the anti-corrosion, ICR and hydrophobic properties of 316L, proposing valuable solutions for high-performance bipolar plates (BPs) in the PEMFC industry.

Design and fabrication of durable poly(3-hydroxybutyrate) (PHB) coating with high adhesion and desirable anti-corrosion performance on Mg alloy for bio-application

To improve the degradation properties of magnesium (Mg) alloy-based temporary implants, a durable polymer coating with high adhesion and desirable anti-corrosion performance is designed in this work. The biodegradable poly(3-hydroxybutyrate) (PHB) with high crystallinity (>60 %) and low glass transition temperature (Tg < 5 °C) is conducted as the protective coating for Mg alloy. The hydrogen evolution rate decreases by 2.56 times with the protection of the PHB coating, while the maximum concentrations (Cmax) of Na+ and Cl− ions penetrated across the PHB film are <0.1 % and 10 % of their total concentrations respectively. Furthermore, a simple approach through the network interdiffusion, hydrogen bonding, and chemical cross-linking is performed to improve the adhesion from 0.19 to 8.36 MPa. The modified PHB coated Mg alloy with a strong interface shows excellent corrosion resistance even after 168 h immersion. The design principle for durable polymer coatings is proposed based on the above results. Moreover, the interfacial bonding is identified by the Density Functional Theory (DFT) computational method. This study demonstrates the prepared PHB coating could act as an ion barrier to supply efficient protection for Mg alloys in vitro and enriches our understanding on the structure-property-performance relationship of polymer coatings.

ZnO-functionalized arabinogalactan and xylan nanocomposite epoxy coating for the corrosion protection of AISI 5140 steel

The anticorrosion performance of epoxy coatings can be enhanced by using biopolymer nanocomposites. The permeability of the corrosive ions through defects and pores can be prevented by the functionalization of biopolymers and their introduction into the epoxy matrix. Herein, ZnO-functionalized arabinogalactan and xylan (AG-ZnO and XL-ZnO) nanocomposites were fabricated using ultrasonication and characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA). The surface morphology of the prepared biopolymer nanocomposite was analyzed using scanning electron microscopy (SEM) and transmission electron microscopy (HR-TEM). The corrosion performance of the epoxy coating containing AG-ZnO and XL-ZnO on AISI 5140 steel was evaluated via electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization studies (PDP) in 3.5 wt% NaCl. The results indicated superior corrosion protection, with inhibition efficiencies of 89.71 % and 93.27 % for the AG-ZnO and XL-ZnO incorporated epoxy coatings, respectively. Furthermore, 0.3 wt% of the prepared biopolymer nanocomposite in the epoxy coatings provided superior protection due to the increased dispersion and even distribution of zinc oxide. After the introduction of the XL-ZnO and AG-ZnO biopolymer nanocomposites, there was a threefold and twofold increase in the charge transfer resistance, respectively, compared to that of the pure epoxy coating. Compared to those of the pure epoxy (icorr = 1.23 ×10-6 A cm−2), the icorr values of the XL-ZnO-EP (icorr = 0.16 ×10-6 A cm−2) and AG-ZnO-EP (icorr = 0.65 ×10-6 A cm−2) coatings significantly decrease. The prepared coatings were subjected to water contact angle measurements and the 3D topographical morphology was determined using atomic force microscopy (AFM). A reduced roughness was observed for the prepared coatings.

TiO2-Mesoporous Ceria Carrier Modified with Sodium Benzoate: An Innovative Polyurethane Matrix for Enhanced Corrosion Protection of steel

An advanced corrosion protection system, distinguished by multilevel corrosion inhibition, was developed by integrating modified hybrid carriers strategically reinforced within a polyurethane (PU) matrix. For this purpose, mesoporous ceria (mCeO2) was synthesized via a hydrothermal hydrolysis process and incorporated with titanium butoxide to synthesize a hybrid core-shell titania mesoporous ceria (TiO2/mCeO2) carrier system. The TiO2/mCeO2 carrier system was modified with sodium benzoate (SB used as a corrosion inhibitor) to develop a modified TiO2/mCeO2-SB system. The synthesized modified particles were then reinforced into the polyurethane-based matrix to study the corrosion inhibition performance. Benefitting the corrosion-inhibiting properties of modified polyurethane-based coatings, the reinforcement of these modified TiO2/mCeO2 particles resulted in a notably improved anti-corrosion performance in the coating after immersion in 3.5 wt. % NaCl solution for four weeks, the impedance was estimated to be 96.65 GΩ.cm2, which is nearly four orders of magnitude than that of blank PU coatings. This is attributed to the synergistic anti-corrosion performance of TiO2 and SB. The protective layer formed due to the interaction of titania and hydroxyl ions resulted in the formation of Ti(OH)4 and SB absorbed on the steel surface, making iron unavailable for further electrochemical reaction. This work reports on the strategy to build a corrosion inhibition coating system, which introduces a new perspective for extending the lifespan of metals.

Fabrication of CNTs/MMT/PPS composite hydrophobic coatings on metal with enhanced anticorrosive and self-cleaning performance

Although much work has been reported on anticorrosive coatings at this stage, most materials are confronted with a variety of harsh environments in practical applications, posing extreme challenges to the various properties of the coatings. In this study, carbon nanotube/montmorillonite/polyphenylene sulfide (CNTs/MMT/PPS) composite coatings were prepared by air spraying method. CNTs-MMT composite fillers with nanostructures were prepared by the amide reaction of 3-aminopropyltriethoxysilane (APTES) modified MMT and carboxylated CNTs. The particle size distribution test demonstrated that the amidated CNTs-MMT exhibited superior dispersion performance compared to CNTs and MMT alone, resulted in a more homogeneous and dense coating. The coatings obtained by combining the low surface energy of polytetrafluoroethylene (PTFE) exhibits hydrophobicity and has excellent self-cleaning properties. The electrochemical corrosion current density of the composite coating was three orders of magnitude lower than that of bare iron, and the corrosion efficiency was 99.43 %, demonstrating excellent corrosion resistance. The thermogravimetric test results showed that the CNTs/MMT/PPS composite coatings displayed excellent thermal stability up to 530 °C. Therefore, the CNTs/MMT/PPS composite coating possesses significant advantages in the field of anti-corrosion due to its enhanced durability, heat resistance, and corrosion resistance.

Towards sustainable steel corrosion protection: expanding the applicability of natural hydrolyzable tannin in epoxy coatings via metal complexation

The study aimed to develop inhibitive pigments based on the natural biopolymer tannin through metal complexation, as an effective and eco-friendly alternative to conventional inhibitive pigments in epoxy coatings for steel protection in marine environments. Initial screening of metal cations for tannin complexation was conducted via steel immersion tests in 3.5 wt% NaCl solution. The combination of tannin with Zn2+ and Ce3+ both exhibited outstanding corrosion inhibition performance. After a 14-day immersion period, the inhibition efficiency reached 79.0 % and 74.0 % respectively, compared to 53.9 % for pure tannin. The more uniform formation of iron-tannin complexes and the co-deposition of metal hydroxides/oxides are believed to contribute to a synergistic effect, as confirmed by ATR-FTIR and SEM-EDS analysis. Further, considering both inhibition efficiency and eco-friendliness, the cerium(III)-tannin complex (CeTA) pigment was successfully synthesized and incorporated into anticorrosive epoxy coatings. Salt spray exposure and electrochemical impedance spectroscopy (EIS) measurements consistently demonstrated improved pigment compatibility with the epoxy matrix and reinforced coating anticorrosive performance.

Influence of Soda and Kraft lignin in polyurethane coatings for the corrosion protection of mild steel in 3.5 % NaCl solution

This study highlights the potential of coconut shell biomass waste-derived lignins (CSL) as corrosion inhibitors to reinforce the coating properties of polyurethane. The utilization of CSL involves a green approach to prepare eco-friendly metallic coatings. Herein, lignin was extracted via Kraft and Soda pulping processes. The present findings indicated that the percentage yield of Soda lignin (SL) (26.43 ± 0.75 %) was significantly higher than that of Kraft lignin (KL) (8.52 ± 0.39 %). Electrochemical impedance spectroscopy and potentiodynamic polarization corrosion monitoring techniques were used to evaluate the anticorrosive performance of modified polyurethane coatings on mild steel exposed to 3.5 % NaCl solution. In this study, doping concentration of 5 wt% KL and SL into polyurethane attained the optimum anticorrosion performance. The surface conditions of uncoated and coated mild steel substrates were investigated through scanning electron microscopy/energy dispersive X-ray (EDX) analysis, salt spray and adhesion tests. EDX analysis demonstrated that polyurethane added with 5 wt% doping concentration of SL contained the highest content of Fe (86.05 wt%) compared to 5 wt% KL which contained 79.64 wt% of Fe, whereas neat polyurethane coating contained 75.43 wt% of Fe. Hence, enhanced corrosion protection of polyurethane through the addition of CSL, particularly SL, possesses a viable and an effective green approach to utilize coconut shell biomass waste for the application as a potential corrosion inhibitor in organic coatings.

Amelioration of protective organic layer using acenaphthene-based inhibitor responsible for excellent anti-corrosion performance: Experimental and computational perspectives

Despite the engineering promise offered by the co-existence of organic substances in protecting vulnerable metallic materials from corrosive environments, the interaction and formation mechanisms that induce the development of new materials with improved structural properties remain less understood. This study investigated the corrosion inhibitory properties of two acenaphthene derivatives, acenaphthylene-1,2‑dione (ACP) and 1,2-dihydroacenaphthylen-1-ol (DCP), as inhibitors for N80 steel in a 15 % HCl solution. The anticorrosive effectiveness of ACP and DCP compounds was evaluated through multiple research methods, including weight loss analysis, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and surface characterization using scanning electron microscopy (SEM). The experimental findings demonstrate that ACP exhibits superior inhibition performance compared to DCP, with an inhibition efficiency of 93.54 % for ACP and 73.12 % for DCP at an optimum concentration of 5 × 10–3 M. EIS data show that the charge transfer resistance increases with higher concentrations of both compounds. PDP results indicate that ACP and DCP act as mixed-type inhibitors without altering the corrosion mechanism. The kinetic parameters of corrosion adsorption follow the Langmuir isotherm, highlighting a competition between physical and chemical interactions. To investigate how the geometric structures resulting from functional groups influence their interaction with the metal surface, theoretical calculations employing density functional theory (DFT), molecular dynamics (MD), and density-functional tight-binding (DFTB) were conducted. These calculations were aimed at gaining insights into the adsorption behavior of ACP and DCP on the metal surface and their interfacial mechanism. The calculations demonstrate that the molecule possessing twin donor atoms along with p-type orbitals of aromatic rings significantly influenced the formation of a protective film with a uniform distribution. This configuration exhibited superior corrosion performance compared to a molecule containing only one hydroxyl group (—OH). Theoretical calculations further suggest that ACP exhibits stronger adsorption ability, with the two oxygen atoms identified as the most reactive sites, indicating their tendency to donate electrons to the iron surface. The robust resonance-stabilized structure of ACP enhances the stability of the molecules, facilitating its interaction and adsorption onto the metal surface compared to the DCP inhibitor. Overall, the superior inhibition performance of ACP is attributed to the close bonding of twin donor fragments within the ACP molecule, forming a more compact adsorbed inhibitor film on the steel surface.

Sol-gel coating containing carbon quantum dots for effective corrosion prevention

This study investigates the impact of carbon quantum dots (CQDs) on the corrosion protection properties of sol-gel coating on AM60B alloy. CQDs were synthesised via microwave technique and characterised using Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), and X-ray Diffraction (XRD). Adding 50 ppm CQDs eliminated micrometric cracks in the coating due to chemical bonding with the silica network. Transmission Electron Microscope (TEM) images revealed that CQDs are well dispersed at 50 ppm in the coating. Also, the Atomic Force Microscopy (AFM) confirmed that this concentration reduces the coating's roughness. Electrochemical Impedance Spectroscopy (EIS) in sodium chloride solution revealed a significant reduction in both electrical double- layer and sol-gel layer capacitances after adding 50 ppm CQDs. This indicates reduced penetration of the corrosive electrolyte, attributed to pore blocking and the elimination of micrometric cracks. After 48 h of immersion, the polarisation resistance (Rp) increased from 0.006 to 0.353 MΩ cm2, significantly enhancing the anti-corrosion performance. However, higher concentrations (100 and 200 ppm) of CQDs negatively impacted the corrosion resistance due to the accumulation and micrometric crack formation.

Influence of crystalline Zn-Ag nanoalloy electrodeposits on their anti-corrosion and hardness performance in engineering applications

Influence of crystalline Zn-Ag nanoalloy electrodeposits on their anti-corrosion and hardness performance in engineering applications

Satisfactory Tensile Strength and Strain of Recyclable Polyurethane with a Trimaleimide Structure for Thermal Self-Healing and Anticorrosive Coatings.

Bismaleimide (BMI) is often used as the cross-linking reagent in Diels-Alder (D-A)-type intrinsic self-healing materials (DISMs) to promote the connectivity of damaged surfaces based on reversible D-A bond formation on the molecular scale. Until now, although DISMs have exhibited great potential in the applications of various sensors, electronic skin, and artificial muscles, it is still difficult to prepare DISMs with satisfactory self-healing abilities and high tensile strengths and strains at the same time, thus largely limiting their applications in self-healing anticorrosive coatings. Herein, symmetrical trimaleimide (TMI) was successfully synthesized, and trimaleimide-structured D-A self-healing polyurethane (TMI-DA-PU) was prepared via the reversible D-A reaction (cycloaddition of furan and maleimide). As a DISM, TMI-DA-PU exhibits apparently higher self-healing efficiency (98.7%), tensile strength (25.4 MPa), and strain (1378%) compared to bismaleimide-structured D-A self-healing polyurethane (BMI-DA-PU) (self-healing efficiency, 90.2%; tensile strength, 19.3 MPa; strain, 1174%). In addition, TMI-DA-PU shows a high recycling efficiency (>95%) after 4 cycles of recycling. A series of characterizations indicate that TMI provides more monoene rings as the self-healing sites, forms denser cross-linked structures compared to BMI, and is, thus, more appropriate to be used for DISM applications. Moreover, the barrier abilities of coatings can be semi-quantitatively expressed by the impedance value at 0.01 Hz (|Z|0.01Hz). The |Z|0.01 Hz value of the TMI-DA-PU coating is 3.93 × 109 Ω cm2 on day 0, which is significantly higher than that of the BMI-DA-PU coating (6.76 × 108 Ω cm2 on day 0), indicating that the denser rigid cross-linked structure of TMI results in the small porosity in the TMI-DA-PU coating, thus effectively improving the anticorrosion performance. The construction of DISMs with the structure of TMI demonstrates immense potential in self-healing anticorrosive coatings.

Effects of Nanoadditives on the Anticorrosion Performance of Nanocomposite Coatings: A Review

Effects of Nanoadditives on the Anticorrosion Performance of Nanocomposite Coatings: A Review