Anti-corrosion Film Research Articles

THE ROLE OF INHIBITORS IN THE PROCESS OF FORMING A PROTECTIVE ANTI-CORROSION FILM ON THE STEEL SURFACE OF EQUIPMENT IN HEAT SUPPLY SYSTEMS

Known methods of combating internal corrosion of metal pipes in heat supply systems, by conducting anticorrosive water treatment, cannot maximize the effect of their corrosion protection. There is no universal method of anticorrosive water treatment, each method has its advantages and disadvantages, taking into account the condition of the pipes, the speed of the water supply, and the composition of the water. However, optimal inhibition of corrosion occurring on the inner surface of pipelines of heat supply equipment can be achieved by creating a protective film on the metal inner surface of the pipe using inhibitors. Corrosion products may interfere with the good adhesion of the resulting film to the surface. For more complete and effective inhibition of the surface and dosing of the inhibitor, preliminary chemically active cleaning of the surface with a solution of sulfuric acid, at its concentration of 3%, provided for washing solutions in a circulating mode for 3-5 hours, can contribute. The metal surface of the pipe cleaned by activation contributes to a stronger adhesion of the inhibitor to the surface and the creation of a film with high protective properties. To establish the quality of the obtained anticorrosive films, a JSM6490LV scanning electron microscope with INSAenergy dispersion microanalysis and HKL – Basic structural analysis systems with a useful magnification of 300.000 in combination with a high-performance Varian ProStar liquid chromatograph, an atomic adsorption spectrometer contrAA-300 with a plasma analyzer from 180 to 900 nm was used.The work is devoted to the selection of phosphate and high-modulus silicate inhibitors in order to form a protective film on the metal surface of the pipe to prevent the formation of scale deposits and protect against corrosion when the coolant passes through the pipe to the consumer.

Electrochemical Synthesis of Zeolite Coatings with Controlled Crystal Polymorphism and Self-Regulating Growth.

Zeolite coatings are studied as molecular sieves for membrane separation, membrane reactors, and chemical sensor applications. They are also studied as anticorrosive films for metals and alloys, antimicrobial and hydrophobic films for heating, ventilation, and air conditioning, and dielectrics for semiconductor applications. Zeolite coatings are synthesized by hydrothermal, ionothermal, and dry-gel conversion approaches, which require high process temperatures and lengthy times (ranging from hours to days). Here, we report the first zeolite coatings synthesized via electrochemical deposition on a cathodic electrode, with controlled crystal polymorphism achieved within subhourly duration. We demonstrate this approach by developing sodium zeolite (e.g., sodalite (SOD), NaA (LTA), and Linde Type N (LTN)) coatings on a titanium electrode and extending the synthesis method to porous stainless steel. The coating morphology and crystallinity depend on the temperature, time, and applied current. The coating thickness is independent of the applied current, showing the presence of a self-regulating mechanism to ensure a uniform coating thickness across the metal surface. The electrochemical zeolite growth mechanism was elucidated with high-resolution transmission electron microscopy, and applications of the resultant zeolite coatings for oil/water separation and ethanol/water pervaporation were exploited. Electrochemical synthesis represents a novel, simple, fast, and environmentally friendly approach to preparing zeolite coatings. It can potentially be generalized for developing zeolite materials with diverse framework structures, morphologies, and orientations for substrates with complicated geometries.

Extraction of lignin from lignocellulosic biomass (bagasse) as a green corrosion inhibitor and its potential application of composite metal framework organics in the field of metal corrosion protection.

With increasing awareness of environmental protection, additional attention has been given to environmentally friendly metal anticorrosion research. In this paper, the green organic corrosion inhibitor sodium lignosulfonate (SLS) was extracted from bagasse waste, and a Ce-MOF@SLS smart anticorrosive film containing the inhibitor was prepared on the surface of an aluminum alloy by in situ electrodeposition. The material was characterized by SEM, EDS, FT-IR, XRD and XPS, and its corrosion resistance was tested with EIS and neutral salt spray tests. The electrochemical data showed that the Ce-MOF@SLS film reached a corrosion current density of 3.36 × 10-8 A/cm2, and no corrosion spots appeared after 105 days of salt spray experiments, indicating that the smart film provided long-lasting protection for aluminum alloys. The antiseptic mechanism of the Ce-MOF@SLS smart film was verified by quantum chemical calculations and molecular dynamics simulations. The research result not only provide a new method for the study of green intelligent anti-corrosion films for aluminum alloys, but also offer a novel approach to the treatment of domestic waste.

Advanced EXAFS analysis techniques applied to the L-edges of the lanthanide oxides.

The unique properties of the lanthanide (Ln) elements make them critical components of modern technologies, such as lasers, anti-corrosive films and catalysts. Thus, there is significant interest in establishing structure-property relationships for Ln-containing materials to advance these technologies. Extended X-ray absorption fine structure (EXAFS) is an excellent technique for this task considering its ability to determine the average local structure around the Ln atoms for both crystalline and amorphous materials. However, the limited availability of EXAFS reference spectra of the Ln oxides and challenges in the EXAFS analysis have hindered the application of this technique to these elements. The challenges include the limited k-range available for the analysis due to the superposition of L-edges on the EXAFS, multielectron excitations (MEEs) creating erroneous peaks in the EXAFS and the presence of inequivalent absorption sites. Herein, we removed MEEs to model the local atomic environment more accurately for light Ln oxides. Further, we investigated the use of cubic and non-cubic lattice expansion to minimize the fitting parameters needed and connect the fitting parameters to physically meaningful crystal parameters. The cubic expansion reduced the number of fitting parameters but resulted in a statistically worse fit. The non-cubic expansion resulted in a similar quality fit and showed non-isotropic expansion in the crystal lattice of Nd2O3. In total, the EXAFS spectra and the fits for the entire set of Ln oxides (excluding promethium) are included. The knowledge developed here can assist in the structural determination of a wide variety of Ln compounds and can further studies on their structure-property relationships.

Improving the interfacial bonding strength of a silane anticorrosion film on copper surfaces using small-molecule corrosion inhibitors

The weak binding ability of silane to copper surfaces restricts its use in copper anticorrosion. In this study, the P–OH groups in etidronic acid (HEDP) were utilized to establish chemical bonds with copper and to react with 3-mercaptopropyltrimethoxysilane (PropS-SH), serving as a bridging mechanism to enhance the anchoring of silane onto copper surfaces. Moreover, the presence of HEDP promoted the condensation of silane, leading to the formation of a denser and thicker film with outstanding corrosion resistance. SEM results indicated that the thickness of the PropS-SH/HEDP film was about 125 nm, and defects at the copper–film interface were repaired. Electrochemical tests demonstrated that the PropS-SH/HEDP film exhibited remarkable corrosion resistance, achieving an anticorrosion efficiency of 99.95 %. Immersion testing showed that the PropS-SH/HEDP film was capable of withstanding immersion in a 3.5 wt% NaCl solution for 10 days, displaying a durability 5 times greater than that of the standalone silane film.

Experimental and theoretical investigations of the anti-corrosion film derivated from bio-based melatonin on AA5052 aluminum alloy surface

In this work, the effect of the bio-based melatonin (MEL) on the corrosion inhibition of AA5052 aluminum alloy in 3 wt% NaCl solution has been studied by weight-loss experiments, electrochemical measurements and surface analysis. MEL inhibits the corrosion of AA5052 aluminum alloy in 3 wt% NaCl solution very well, resulting in a positive shift of the corrosion potential and the pitting potential. The corrosion inhibition efficiency reaches 71.76% at 2 mM MEL. The FT-IR, SEM, XPS and theoretical calculation are used to investigate its corrosion inhibition mechanism. It indicates that MEL coordinates with Al3+ ions via its N (9) atom and O (10) atom to form a surface complex film. This protective film retards the corrosion of AA5052 aluminum alloy significantly. This biomolecule is a promising anti-corrosion additive to protect aluminum alloys heat-exchange in seawater desalination plant.

Tribo-electrical properties of copper matrix composites in salt-fog environment

To enhance the reliability of floating offshore wind platforms exposed to salt-fog environment, a new material, CNTs-MoS2/Cu, was developed for slip rings. Tribo-electrical properties of composites in salt-fog environment were explored. A novel method for characterizing current-carrying stability, based on correlation dimension, was proposed. When compared to copper, the correlation dimension decreased by 31.43%. It reveals that composites exhibit superior current-carrying stability compared to copper in salt-fog environment. The wear mechanism is further revealed. CNTs enhance the damage resistance of friction film, while MoS2 contributes lubrication. The appropriate addition of CNTs and MoS2 leads to the formation of an intact conductive lubrication anti-corrosion film on the surface, reducing the erosive impact of salt fog.

Preparation and properties of MAO self-healing anticorrosion film on 5B70 Al alloy

Micro-arc oxidation (MAO) was a new surface treatment technology for Al alloys. However, the MAO ceramic film could not provide long-term protective performance owing to its inherent porous structure. In this work, a new type of CeO2-sealed GO/Al2O3 composite film on 5B70 Al alloy with excellent corrosion resistance was prepared by integrating MAO and the hole sealing technique. The experimental results indicated that the loose and porous MAO ceramic film could serve as a ‘shield’ and a ‘reservoir’, respectively, to obtain improved impedance and sufficient corrosion inhibitor loading. Compared to the original MAO ceramic film or GO/Al2O3 composite film, The GO/Al2O3 composite film after sealing treatment for 60 min had lower porosity and better corrosion resistance. In addition, CeO2-sealed GO/Al2O3 composite film exhibited a positive self-healing effect in 3.5 wt% NaCl solution.

Experimental and DFT Atomistic Insights into the Mechanism of Corrosion Protection of Low-Carbon Steel in an Acidic Medium by Polymethoxyflavones from Citrus Peel Waste

Developing green anticorrosive films is gaining great attention in science and engineering. Citrus fruit peels are mainly discarded as waste, although they can be an excellent repository of phytochemicals, that can be exploited as mitigating agents for corrosion. Herein, we report the high anticorrosion activity of a citrus extract for low-carbon steel in 1 M HCl solution at different temperatures. The main extract constituents were identified by MS and NMR. Two polymethoxyflavones (PMFs), namely nobiletin and heptamethoxyflavone, were identified as major constituents of the extract and the crude PMFs-based extract was investigated for corrosion protection. Using potentiodynamic polarization, weight loss and electrochemical impedance spectroscopy (EIS) methods, this extract revealed improved inhibition efficiency of 94%. The inhibition mechanism was elucidated by considering electrochemical kinetics and adsorption thermodynamics. SEM and UV–vis supported the electrochemical results. PMFs-based extract acted as a mixed-type inhibitor with a Langmuir model of adsorption. Importantly, DFT simulations provided atomic-level insights into the inhibition mechanism and unraveled donor-acceptor interactions between the methoxy groups of PMFs and iron atoms, facilitating the formation of a stable inhibition adsorption layer, and thus supporting the experimental findings. In addition to the physical barrier effect of PMF inhibitor, π-back bonding effect between PMF and steel was suggested.

Fabrication of silane-based surface coating with Ag/TiO2 hybridization and its anti-corrosion performance on metal surface

Surface coating technology is an effective anti-corrosion strategy which can form a layer of anti-corrosion film on metal surface, effectively preventing it from oxidation and corrosion. Among various strategies, silanization treatment of metals is the most commonly used one. However, using silane-based coatings alone often leads to poor anti-corrosion performance due to insufficient mechanical strength and presence of surface defects. In order to improve the corrosion resistance of silane coatings, a hybrid surface coating has been constructed by introducing epoxy resin and Ag/TiO2 nanoparticles into the silane film in this work. After adding epoxy resin, the thickness of the silane film greatly increases, which improves its mechanical properties. Ag/TiO2 nanoparticles can enhance the cross-linking between silane molecules and epoxy resin, thereby preventing formation of surface defects. The epoxy resin-silane-Ag/TiO2 composite surface coating is coated on the surface of AA2024 aluminum alloy using spin coating method. Electrochemical and salt spray tests indicate excellent corrosion resistance performance of the composite coating. This composite coating technology may have potential applications on the surfaces of various metal products such as medical devices and aerospace materials, and will shed light on the development of new surface coating technologies.

Adsorption and anticorrosion studies of newly designed Schiff bases for the protection of EN3B mild steel in 3.5% NaCl solution: A combined experimental and theoretical approach

Three newly synthesized Schiff bases; 5-(diethylamino)-2-[(n-undecylimino)methyl]phenol (NS11), 5-(diethylamino)-2-[(n-tetradecylimino)methyl]phenol (NS14) and 5-(diethylamino)-2-[(n-hexadecylimino)methyl]phenol (NS16) have been presented as efficient corrosion inhibitors for the protection of EN3B mild steel in 3.5% NaCl solution at acidic pH 1.5. The inhibitors were characterized by multitude techniques i.e., Fourier transform-infrared (FT-IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry and single crystal X-ray diffraction (XRD) analysis. An anti-corrosive film of the inhibitors was generated on EN3B mild steel surface by dip-coating method and the presence of adsorbed molecules in a monolayer was detected via reflection absorption infrared spectroscopy (RAIRS). Electrochemical measurements revealed a strong inhibition potential of the inhibitors with the maximum inhibition efficiency of 99.8% achieved by NS16. These results were further complemented by morphological examinations and density functional theoretical (DFT) calculations revealing that the electron donating power of substituents is directly related to the inhibition potential of the inhibitors.

Sustainable development of an effective anti-corrosion film over the St12-steel surface against seawater attacks using Ce(III) ions/tri-sodium phosphate anions

One application of organic compounds is to utilize them as corrosion inhibitors in acidic environments to diminish steel corrosion. These inhibitors do not show very good inhibition properties in saline (NaCl) environments. There have been many studies on boosting these inhibitors’ performance in such environments (especially Cl− containing media). One of the ways that have been proposed is the use of organic and inorganic inhibitors, simultaneously. The synergistic effect of these inhibitors has shown promising results in reducing steel corrosion. In this study, cerium(III) nitrate and tri-sodium phosphate (TSP) was used as organic and inorganic inhibitors to control the corrosion of steel in a 3.5 wt.% NaCl environment. The corrosion measurements were conducted in the 3.5 wt.% NaCl environment by EIS and polarization methods. Surface studies were done by SEM, Raman, GIXRD, and EDS methods. Corrosion studies (EIS and polarization) have revealed that when 500 ppm of Ce(NO3)3 and 500 ppm of TSP are added to the 3.5 wt.% NaCl medium, the highest synergism index (1.27) and inhibition efficiency (73.7%) are achieved. Also, by adding 500Ce-500TPS to the solution, icorr and Rct of steel decreased by about 80% and increased approximately 4-fold, respectively. This improvement in the steel performance against corrosion in the presence of an equal ratio of Ce(NO3)3 and TSP is the outcome of the formation of a hydrophobic dense film (consisting of Ce(OH)3, Ce/Fe-phosphate complexes) on the metal surface. This claim has been proven by SEM/EDS, contact angel, FT-IR, and XRD analysis.

Micro/nanostructured amorphous TiNbZr films to enhance the adhesion strength and corrosion behavior of stainless steel

To improve the corrosion resistance of key components and ensure the service safety of marine equipment, here we combined femtosecond (fs) laser fabrication and magnetron sputtering deposition to develop micro/nanostructured amorphous TiNbZr films. Analysis of the compositional, microstructural, corrosion, and mechanical properties was conducted. The results showed that the TiNbZr films were amorphous, and spherical TiNbZr nanoparticles uniformly covered the fs laser-induced periodic fringe structure. A complex hierarchical micro/nanostructure was formed that was hydrophobic and showed enhanced adhesion strength. The TiNbZr films deposited on fs laser-treated substrates provided the best corrosion resistance, showing a self-corrosion current density of 116 nA/cm2, excellent passive ability, and pitting resistance. The microscratch test revealed that the micro/nanostructures doubled the binding strength of the TiNbZr/316L interface due to the compositional and structural gradients induced by an approximately 20 nm transition layer formed during fs laser processing. This work provides a new method for obtaining anti-corrosion films with a high adhesion strength for marine applications.

Autonomous Self-healable Scratch-free Bilayer Anti-corrosion Film

Thin hydrophobic polymer film, which physically prevents an approach of corrosive media, has been widely used as an anti-corrosion coating for metals. Though polymer film effectively passivates surface of metal, it loses its anti-corrosion property once the film is peeled off by physical damage, such as scratches. Corrosion can be propagated from the exposed area even if the area is small. Therefore, for long-term anti-corrosion, the film should be seamless and completely cover the entire metal surface without scratches. In this study, we introduce an autonomously self-healable hydrophobic coating with superior anti-corrosion property by a combination of self-healable/fluorinated polymers. Schiff-base linkages based polydimethylsiloxane (SC-PDMS) is used as a primary protection layer against corrosive media. The SC-PDMS matrix with the dynamic imine bonds allows scratch-free metal protection layer by reproducible damage healing property. In addition, we applied polytetrafluoroethylene (PTFE) thin film at the surface of the SC-PDMS, which suppresses the reaction of imine bond with water and helps to maintain long-term anti-corrosion property. Eventually, this simple coating of bilayer structure with SC-PDMS and PTFE shows an effective scratch-free corrosive resistance, providing a new way of long-term use of metals.

Electrochemical Study of a Hydrophobic Film of γ-Al2O3/Hdtms on Low Carbon Steel

The corrosion phenomenon affects several low carbon steel structures leading to excessive expenditure on coatings and other alternatives. However, the coatings used usually contain compounds that pollute the environment. Therefore, environmentally friendly, economical and transparent coatings or films have been developed. The sol-gel method is a reliable way for the development of anticorrosive films, as is the case of alumina or silica films. In this work, the protective capacity of an alumina/HDTMS film was studied. The alumina film was sintered at 350, 450 and 550 °C and then the 1% HDTMS film was deposited. The protective ability of the γ-Al2O3/HDTMS film was evaluated by Electrochemical Impedance Spectroscopy (EIS) and Potenciodynamic Polarization Curves (PDP). The electrochemical results showed that the Al2O3/HDTMS film provided better protection compared to the metallic substrate. The contact angle degree was measured and determined that the sintered alumina/HDTMS films showed hydrophobic and superhydrophobic properties.

Azadirachta indica (Neem) self-healing efficacy assessment in epoxy primer coatings: A bio-responsive strategy for counteracting corrosion

The active anticorrosion performance of epoxy coatings containing encapsulated crude vegetal extracts of Azadirachta indica (Neem) leaves to protect aluminium alloy 6061 in seawater was investigated. Ethanol and hexane were the loading solvents. The molecules-metal interaction alongside the formation of an anticorrosive film of the defective coatings was evaluated using electrochemical techniques while adjusting the pH of the seawater. The unloaded scratched epoxy coating was the comparison. In the alkaline chloride solution, the hybrid coatings exhibited better anticorrosion via extrinsic self-healing. XPS validated the composition and chemical species of the bionanocomposites.

Evaluating the Corrosion Inhibition Efficiency of Pyridinium-Based Cationic Surfactants for EN3B Mild Steel in Acidic-Chloride Media

Two new effective corrosion inhibitors, namely N-(n-octyl)-3-methylpyridinium bromide (Py8) and N-(n-dodecyl)-3-methylpyridinium bromide (Py12), have been presented. The cationic pyridinium-based surfactants were analyzed for the corrosion protection of general purpose steel (EN3B) against a strong corrosive media (3.5% NaCl, pH 1.5). The results of the electrochemical measurements, i.e., Tafel polarization, linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) revealed a mixed-type behavior of both inhibitors, and the maximum inhibition efficiency (IE) achieved with Py8 and Py12 was 85% and 82%, respectively. The process of adsorption of synthesized inhibitors followed the Langmuir adsorption isotherm, and a higher value of Kads highlighted the existence of strong interaction between inhibitors and the EN3B mild steel surface. Furthermore, the values of ΔG°ads were calculated to be −32 kJ mol−1 for Py8 and −33 kJ mol−1 for Py12, indicating the coexistence of both physisorbed and chemisorbed molecules. The surface morphology of EN3B mild steel samples was observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM), where the reduced surface roughness in the presence of Py8 and Py12 in chloride media further supported the evidence of an efficient inhibition process. Density functional theory (DFT) calculations reveal excellent correlation with the experimental results, with Py8 showing superior corrosion inhibition potential, signifying that the alkyl chain length and intramolecular charge transfer are crucial factors in deciding the inhibition performance of the synthesized cationic surfactants. Furthermore, this study proposes the mechanism for the adsorption of the surfactant-based inhibitors over the EN3B mild steel surface, which leads to the formation of an effective and protective anticorrosive film.

Investigation of the Effect of Atmospheric Pollution Components of Livestock Premises on the Moisture Absorption of an Anti-corrosion Film

Using a multifactorial experiment of the plan N = 2(4), the influence of the components of air pollution in livestock buildings on the moisture absorption of a film of D-11A plastisol mastic was studied by the gravimetric method. The corresponding dependence equations are obtained, which show a more aggressive effect of hydrogen sulfide and sulfur dioxide on the protective film.

Tetraethyl orthosilicate steam induced silicon-based anticorrosion film enables highly reversible zinc metal anodes for zinc-iodine batteries

Zinc (Zn) metal anodes are badly troubled by the challenges of notorious dendrites and corrosion reactions from H2O and I3− ions during stripping/plating processes, impeding the commercial application of Zn-iodine (I2) batteries. In this work, we report a novel strategy for the in-situ construction of uniform silicon-based anticorrosion films on Zn metal anodes (Zn@Ts) through the treatment of tetraethyl orthosilicate (TEOS) steam on Zn disks for different times. TEOS can be decomposed into three-dimensional (3D) porous inorganic frameworks (SiOxCy) filled with organic polymers (SiCxOyHz) on Zn metal at 180 °C in autoclave. On the one hand, silicon-based composite layers can protect Zn metal from direct contact with aqueous electrolyte and stabilize the electrode/electrolyte interface, which hinders the occurrence of hydrogen evolution as well as corrosion reactions. On the other hand, 3D macroporous structure not only provides strong mechanical framework but also guides Zn2+ flux to homogenize Zn2+ concentration and realize uniform Zn nucleation/deposition, which contributes to suppress the growth of Zn dendrites. Zn@Ts symmetric batteries exhibit better cycling life of 5000 h comparing with bare Zn at 2 mA cm−2 and 2 mA h cm−2. Zn–I2 full-cells can achieve 89 mA h g−1 and 93% capacity retention after 20000 cycles.

Tannin acid induced anticorrosive film toward stable Zn-ion batteries

Aqueous Zn-ion batteries (AZIBs) have been regarded as a promising next-generation energy storage system. However, the poor reversibility of Zn anodes with serious dendrite growth and parasitic reactions degrades the battery performance. Inspired by the anticorrosion strategy for metal protection, an extremely simple and cost-effective method of soaking Zn plate in tannin acid (TA) solution is applied to design ZnTA anticorrosive film on Zn anodes. Robust chemical interaction between Zn and phenolic hydroxyl groups in TA molecules endows ZnTA with the excellent film-forming capacity of ensuring uniform surface and desirable coverage on Zn anodes. A remarkable suppression of parasitic hydrogen evolution during Zn plating is available by ZnTA@Zn anodes, evidenced by in-situ electrochemical gas chromatography (EC-GC). The Symmetric cells with ZnTA@Zn anodes show long-term stability of over 4500 cycles under an ultra-high current density of 30 mA cm−2, verifying the excellent reversibility ZnTA@Zn anodes. Besides, ZnTA anticorrosive film also demonstrates significant capacity to suppress the Zn corrosion resulted from shuttling polyiodide. Consequently, highly-reversible Zn-I2 batteries with excellent rate performance and ultra-long lifespan (20,000 cycles at 6 A g−1) are achieved with ZnTA@Zn anodes. This finding emphasizes the protective mechanism of anticorrosive films against electrolyte/polyiodide corrosion which contributes to the highly-reversible Zn anodes.