Metal Corrosion Research Articles

Single-atom Ru modified flake g-C3N4 enhances photogenerated electron transport for rapid degradation of tetracycline antibiotics: Non-radical mechanism and ecotoxicity studies

Design of green and low-cost single-atom catalysts (SACs) with high-performance is key to moving photocatalytic degradation of antibiotics toward applications. In order to achieve SACs for large-scale manufacturing, we prepared ultrathin flake carbon nitride (FCN) by low-energy-consuming physical knockout means, and also applied an in situ growth strategy with stable and easy-operating effect to anchor the Ru element on FCN in the form of single atom. Notably, in the PMS/Vis/0.5Ru-FCN system, the degradation rate of tetracycline achieved 100 % in just five minutes, with an apparent rate constant of 0.236 min−1. Ru-FCN exhibits selective and stable determination due to narrow bandgap, unique photoresponsivity and low photogenerated carrier complexation rate. Mechanism investigation reveal that Ru-N4 sites accelerated the electron transfer between Ru-FCN and PMS, while the low oxidation state of Ru elements reduced the risk for metal corrosion. DFT calculations predict the attack sites of reactive oxygen species. This work provides a rational explanation for the charge transfer and resistance to external disturbance by Ru single atom, and it also provides a new direction to enhance the efficiency of water treatment.

Biosurfactants: Chemical Properties, Ecofriendly Environmental Applications, and Uses in the Industrial Energy Sector

The exploitation of nature and the increase in manufacturing production are the cause of major environmental concerns, and considerable efforts are needed to resolve such issues. Oil and petroleum derivatives constitute the primary energy sources used in industries. However, the transportation and use of these products have huge environmental impacts. A significant issue with oil-related pollution is that hydrocarbons are highly toxic and have low biodegradability, posing a risk to ecosystems and biodiversity. Thus, there has been growing interest in the use of renewable compounds from natural sources. Biosurfactants are amphipathic microbial biomolecules emerging as sustainable alternatives with beneficial characteristics, including biodegradability and low toxicity. Biosurfactants and biosurfactant-producing microorganisms serve as an ecologically correct bioremediation strategy for ecosystems polluted by hydrocarbons. Moreover, synthetic surfactants can constitute additional recalcitrant contaminants introduced into the environment, leading to undesirable outcomes. The replacement of synthetic surfactants with biosurfactants can help solve such problems. Thus, there has been growing interest in the use of biosurfactants in a broad gamut of industrial sectors. The purpose of this review was to furnish a comprehensive view of biosurfactants, classifications, properties, and applications in the environmental and energy fields. In particular, practical applications of biosurfactants in environmental remediation are discussed, with special focus on bioremediation, removal of heavy metals, phytoremediation, microbial enhanced oil recovery, metal corrosion inhibition, and improvements in agriculture. The review also describes innovating decontamination methods, including nanobioremediation, use of genetically modified microorganisms, enzymatic bioremediation, modeling and prototyping, biotechnology, and process engineering. Research patents and market prospects are also discussed to illustrate trends in environmental and industrial applications of biosurfactants.

Recent development in polymer coating to prevent corrosion in metals: A review

Corrosion in metals is a pervasive and costly issue across various industries, from infrastructure to manufacturing. Corrosion is a complex electrochemical process, and mitigating it is paramount to extend the lifespan and maintain the integrity of metal structures and components. This review study provides a thorough overview of the state-of-the-art use of polymer coatings to stop metal corrosion. It then delves into polymer coatings’ essential properties and advantages, highlighting their role in corrosion inhibition. The paper surveys recent advancements in polymer coating techniques and their compatibility with different metal substrates. The case studies and real-world applications where polymer coatings have been successfully employed to prevent corrosion in diverse settings, including marine environments, automotive components, and aerospace structures, are explored. Case studies illuminate the efficacy of these coatings, showcasing their role in safeguarding assets, reducing maintenance costs, and promoting sustainability. By analyzing these cases, the paper elucidates the practical effectiveness of polymer coatings in corrosion prevention. This review article addresses numerous ways of shielding metals from corrosion, focusing on nanomaterials, conducting polymers, nano-composites, and carbon-based materials for corrosion resistance. This literature review stands out for its thorough analysis of the most recent developments in this field and the ways in which various polymer coatings are being used to prevent corrosion.

Evaluation of Artichoke Extract as a Corrosion Inhibitor for Copper and OL45 in Aggressive Environments

Abstract Metal corrosion is a significant issue in areas such as transport, construction, or production, with effects on equipment productivity, user safety, and finally, the costs related to the replacement of affected components. Research in recent years has focused on the discovery of substances capable of significantly reducing the corrosion rate of metals and alloys with a minimal impact on the environment. A promising category of green corrosion inhibitors represents active components from natural extracts. Corrosion experiments have been focused on the use of artichoke (Cynara scolymus) stem extract as a corrosion inhibitor for copper and mild steels such as OL45 in H2SO4 0.5 mol L-1 and NaCl 3.5% environments. The electrochemical behaviour of the active components in the artichoke extract was studied using cyclic voltammetry on Pt electrode, and their inhibitory effect has been demonstrated by using electrochemical techniques such as linear voltammetry at a speed of 1 mV s-1 and chronoamperometry method in the absence, respectively, presence of 1, 2, 4, and 8 g L-1 extract. The variation of parameters such as corrosion potential Ecorr, corrosion current icorr, and impedance values with increasing concentrations shows that the artichoke extract greatly reduces the corrosion rate. To complement the corrosion studies carried out, quantum chemical calculations were performed by using the B3LYP/6-31G* basis set, and the descriptors EHOMO, ELUMO, dipole moment, ionization energy, and molecular hardness substantiated the inhibitory effect. Considering artichoke extract components, this study presents a potential prospect for using natural extracts in anti-corrosion protection as well as an ecological alternative to standard corrosion inhibitors.

Corrosion of Copper, Cupronickel, Nickel Aluminium Bronze and Super-Duplex Stainless Steel Rotating Cylinder Electrodes in Seawater under Turbulent Flow Conditions

The corrosion of uncoated metals in a marine environment restricts the choice of suitable engineering metals and alloys. Anodic dissolution of metal and cathodic reduction of oxygen are important processes and formation of a surface oxide film can affect both electrode reactions. Charge transfer and mass transfer data can provide information on corrosion rate and mechanism. Several metals and alloys having a history of use in marine engineering are considered, including copper, two copper alloys (cupronickel and nickel aluminium bronze) plus a more recent addition to strong, corrosion resistant alloys (a super duplex stainless steel). The rotating cylinder electrode offers the benefits of a controlled, turbulent flow of electrolyte, facilitating controlled mass transfer in a compact cell geometry which is well-suited to bench-top operation. These features are illustrated using a variety of electrochemical techniques, including open-circuit potential vs time monitoring, linear sweep voltammetry, rotation speed step- or potential step current transients and linear polarisation resistance measurements. Seawater taken from Langstone Harbour, Hampshire, UK, was filtered, air-saturated, pH 8.0 and maintained at 25 °C. Dimensionless group correlations and graphical plots (using an analogous approach to the Koutecky-Levich equation for an RDE) enabled contributions of charge transfer-, mixed- and mass transfer- controlled data to be appreciated, allowing the Tafel slopes of electrode reactions, the diffusion coefficient of dissolved oxygen, the mass transfer coefficient for oxygen reduction and the mean corrosion rate to be estimated.

The Performance of Amino‐ and Hydroxy‐Substituted Benzothiazoles in Inhibiting the Corrosion of Carbon Steel in HCl and the Molecular‐Level Mechanisms

AbstractIn the pickling process and acidizing program for oil wells, the acidic corrosion of metals is a problem that needs to be addressed. Various acid corrosion inhibitors have been studied and used to mitigate the acidic corrosion of carbon steel. In this paper, the corrosion inhibition of 2‐aminobenzothiazole (2 N‐BT), 2‐amino‐4‐hydroxybenzothiazole (2 N4O‐BT), and 2‐amino‐6‐hydroxybenzothiazole (2 N6O‐BT) on carbon steel in 0.5 mol/L HCl was investigated using electrochemical and quantum chemical methods. All three molecules exhibited corrosion inhibition effects. Compared to 2 N‐BT, 2 N4O‐BT and 2 N6O‐BT showed less sensitivity to the environmental conditions and the surface state of the metal. Among them, 0.0010 mol/L 2 N6O‐BT demonstrated the highest and most persistent corrosion inhibition, exhibiting a mixed inhibition mechanism with cathodic inhibition dominance. The adsorption of 2 N6O‐BT on the carbon steel surface was found to be non‐uniform, preferentially adsorbing at certain active sites on the surface, following Freundlich‐Langmuir thermodynamic characteristics. It showed initial strongly adsorbed points and weakly adsorbed regions. With continued adsorption of 2 N6O‐BT, the differences between strongly adsorbed points and weakly adsorbed regions decreased. The introduction of hydroxyl groups, especially in 2 N6O‐BT, extended the negative potential region and enhanced the coordination activity of the molecule, generating the orbital distribution that was advantageous to flat adsorption and the formation of feedback bonds. This provided a molecular structural basis for the excellent corrosion inhibition properties of 2 N6O‐BT.

Corrosion Inhibition Performances of Amino Acids Corrosion Inhibitors on Carbon Steel in Sulphuric Acid Medium

Abstract The amino acids have great potential in inhibiting metal corrosion. The corrosion inhibition performances of amino acids corrosion inhibitors on A3 carbon steel in sulphuric acid medium were investigated by weight loss method. The corrosion inhibition performances of the alanine, glycine, aspartate, arginine and methionine increase gradually with the dosage of amino acid corrosion inhibitor increase gradually. The five composite corrosion inhibitors were prepared by compound of the five amino acid and potassium iodide respectively to improve the corrosion inhibition performances of amino acids. The corrosion inhibition rate of the five composite corrosion inhibitors is about 20% higher than the amino acid corrosion inhibitors respectively. The amino acid and potassium iodide composite corrosion inhibitors have good protective effects on A3 carbon steel at 30-45°C. The amino acid and potassium iodide composite corrosion inhibitors used for sulfuric acid medium have good protective effects on A3 carbon steel.

Carbon Micron-size Content Dependency in Epoxy/Carbon Composite Coated onto SPCC Plate for Automotive Bodies Protection

Conventional epoxy coating for surface metal corrosion protection reported many unsolved technical problems. Adding filler in the epoxy could enhance the promising properties of the composite coating. Our work describes in detail the synthesizing and characterizing epoxy/carbon composite coating. Epoxy was mixed with thinner high gloss (HG) and hardener and stirred using a stirrer apparatus. After blending, various carbons were added (1 wt. %, 3 wt. %, and 5 wt. %) and then appropriately stirred. The different mixture composite was coated onto the steel plate cold rolled coiled (SPCC) plate using high-volume low-pressure (HVLP) in two passes. Various characterizations were performed, including crystallographic orientation, Infra-Red (IR)-spectra, surface morphology, thickness, hydrophobicity, hardness, and corrosion using X-ray diffraction (XRD), Fourier transform infrared (FTIR), Scanning electron microscopy (SEM), portable dry film coating thickness (DFT), digital camera, Vickers microhardness tester, and Potentiostat, respectively. More carbon micron-sized content led to elevate the peak intensity, surface bumpiness, and hydrophobicity. The uppermost external bumpiness and hydrophobicity values are 23.51 µm and 101◦. Hardness depends on carbon content and more carbon leads to an increase in the hardness of the composited coating. The highest average Vickers hardness value is 28.24 HV. The coating thickness influenced the corrosion rate, more coating thickness promoted lesser corrosion rate. The highest coating thickness (60.8 µm) promoted a corrosion rate of around 5.65×10−4 mmpy.

Rapid quantitative analysis of three elements (Al, Mg and Fe) in molten zinc based on laser-induced breakdown spectroscopy combined with machine learning algorithm

Hot-dip galvanizing represents one of the most cost-effective methods for the prevention of metal corrosion, and is therefore employed extensively across a range of fields. Carrying out the research and development of technology and devices for quantitative analysis of chemical elements in hot-dip galvanising process can provide theoretical basis and technical support for the efficiency of hot-dip galvanising process and reduction of energy consumption. A machine learning-assisted LIBS combined with a programmable logic controller (PLC) for simultaneous on-line/in-site monitoring of multiple elements in hot-dip galvanising solution (molten zinc) was developed in the current study. The LIBS spectral data of the on-site hot-dip galvanising solution was collected under optimised experimental conditions. In order to further reduce the influence of experimental noise on the analysis performance, the on-site LIBS spectral data were preprocessed and anomalous spectral data were screened based on normalisation and principal component analysis-mahalanobis distance (PCA-MD). On the basis of the optimised data, component prediction models for three key elements of on-site hot-dip galvanising solution were constructed. The storage and re-call of the model was achieved based on python combined with LabVIEW, thus real-time prediction of the on-site component content of hot-dip galvanising solution was achieved. The results show that the random forest model presents the best prediction results, in which the R2 is 0.9978 and the RMSE is 0.0013% for Al, the R2 is 0.9984 and the RMSE is 0.0011% for Mg, and the R2 is 0.9932 and the RMSE is 0.0001% for Fe. From the on-site analysis results of the constructed model, its MRE of Al, Mg and Fe is 0.0098, 0.0236, and 0.2102, respectively. In summary, the in-situ/on-line analysis system of hot-dip galvanising solution combined with machine learning constructed in this study shows excellent performance, which can satisfy the needs of hot-dip galvanising solution production site. This study is expected to provide theoretical basis and technical reference for quality control and process optimisation in other production sites in the metallurgical field.

Enhancing Resistance to Corrosion and Fouling Using Epoxy Coatings with Superhydrophobic Cells

AbstractAs maritime transport becomes increasingly important, metal corrosion results in significant economic losses. Superhydrophobic materials have significant potential for corrosion prevention. However, poor compatibility between superhydrophobic materials and resin reduces the long‐term corrosion resistance. Interfacial strengthening cells (IS‐Cells) are designed to maintain superhydrophobicity and retain active hydroxyl groups participating in resin‐curing. IS‐Cells also contribute to achieving the maze effect. A novel anti‐corrosion IS coating is fabricated by compatible IS‐Cells and epoxy. IS coatings feature smooth surfaces and vertical compactness, protecting against liquid and gaseous corrosive medium. Strong diffusion resistance and extended diffusion distance ensure long‐term corrosion resistance of IS coatings. Approximately 85 µm of IS coatings remain corrosion‐free after 112 days of immersion in the NaCl solution. The low‐frequency impedance, self‐corrosion potential, and self‐corrosion current density are 1.68 × 109 Ω cm2, −0.0708 V, and 5.38 × 10−11 A cm−2, respectively. IS coatings can also withstand 2400 h of neutral salt spray testing without corrosion in the artificial scratches. Due to the electrostatic repulsion between the hydrophobic C–F chains onto IS‐Cells and protein molecules, IS coatings maintain anti‐fouling properties after dry‐wet immersion tests in the natural marine environment for 90 days. IS coatings show great potential for marine anti‐corrosion applications.

TEM Analysis and Failure Mechanism Studies of Bromine-Induced Defects in Wafer Fabrication

In wafer fabrication, the contamination of halogen is commonly encountered, such as fluorine, chlorine, bromine. These contaminants can seriously impact product’s quality and yield. In the previous works, we have studied F and Cl-induced metal corrosion and failure mechanisms. In this paper, we will apply TEM analysis technique to study Br-indued corrosion and failure mechanism. Moreover, we will introduce a model of “Br-chain chemical reaction” to explain why even a little bit of Br contamination, it can cause very bad corrosion results, and the formation of the worm-like defects at the side of Al metal lines in wafer fabrication.

Monitoring of metal corrosion by electrochemical methods

Monitoring of metal corrosion by electrochemical methods

Complex Protection of Some Steels in Sulfuric Acid Solutions by 1,2,4-Triazole Derivatives.

The corrosion behavior of steels of various grades in sulfuric acid solutions with the addition of nitrogen-containing corrosion inhibitors has been studied. Compounds containing the 1,2,4-triazole moiety effectively protect low-carbon (St3, St20, 08PS), high-strength (70S2KhA), and stainless steels (1Kh18N9T) not only from corrosion but also from the hydrogen penetration into the metals in concentrated sulfuric acid solutions. In some cases, the degree of steel protection from corrosion by these compounds exceeded 99%. The possibility of creating mixed inhibitors for steel protection containing triazole derivatives and KI has been shown. The rate constants for the main steps of cathodic evolution and hydrogen penetration into steel in sulfuric acid solutions have been determined, and the subsurface concentrations of hydrogen in the metals have been calculated. Triazole derivatives were found to act as inhibitors of hydrogen absorption by steel in H2SO4 solution. The degree of protection of steel from hydrogen absorption can reach 97%. It has been shown that triazole derivatives act as complex inhibitors of steel corrosion in sulfuric acid solutions because, along with strong inhibition of metal corrosion, they prevent hydrogen absorption by steel.

Semi-quantitative elemental imaging of corrosion products from bioabsorbable Mg vascular implants in vivo

While metal materials historically have served as permanent implants and were designed to avoid degradation, next generation bioabsorbable metals for medical devices such as vascular stents are under development, which would elute metal ions and corrosion byproducts into tissues. The fate of these eluted products and their local distribution in vascular tissue largely under studied. In this study, we employ a high spatial resolution spectrometric imaging modality, laser ablation inductively coupled plasma time-of-flight mass spectrometry (LA-ICP-TOF-MS) to map the metal distribution, (herein refered to as laser ablation mapping, or LAM) from Mg alloys within the mouse vascular system and approximate their local concentrations. We used a novel rare earth element bearing Mg alloy (WE22) wire implanted within the abdominal aorta of transgenic hypercholesterolemic mice (APOE−/−) to simulate a bioabsorbable vascular prosthesis for up to 30 days. We describe qualitatively and semi-quantitatively implant-derived corrosion product presence throughout the tissue cross sections, and their approximate concentrations within the various vessel structures. Additionally, we report the spatial changes of corrosion products, which we postulate are mediated by phagocytic inflammatory cells such as macrophages (MΦ’s).

Influence of Reinforcing nano-Al<sub>2</sub>O<sub>3</sub> Particles on Microstructure and Hardness Properties of HVOF Sprayed 80Ni20Cr Coatings

80Ni20Cr coatings produced by high-velocity oxygen fuel (HVOF) thermal spray technique are novel and widely used to improve the corrosion and wear resistance of metal and steel components in many applications, especially in coal-fired power plants. The present study investigated the effects of nano-Al2O3 at 0.5 wt.% on the microstructure of HVOF-sprayed 80Ni20Cr coating deposited on AISI 304L steels corresponding to its coating hardness. The coating was successfully sprayed with a thickness of 150 – 180 µm. The microstructure and phase formed by the coating were analyzed by a field emission electron microscope (FE-SEM) and an X-ray diffractometer (XRD). Synchrotron X-ray fluorescence spectroscopy (SRXRF) was used to confirm the Cr solid solution in the Ni-based coating. The presence of the nano-Al2O3 phase in the 80Ni20Cr coating was characterized by electron backscattered diffraction (EBSD). The nano-Al2O3 particles were homogenously distributed in the coating layers. The incorporation of nano-Al2O3 into 80Ni20Cr enhanced coating characteristics by decreasing surface roughness by 23% and increasing coating hardness by around 4%.

Titanium Cable Cerclage Increases the Load to Failure in Plate Osteosynthesis for Distal Femoral Fractures.

Background and Objectives: The reduction of two-part oblique or spiral fractures of the distal femur using steel wire cerclage prior to plate osteosynthesis is a proven procedure. In addition to being useful in fracture reduction, wire cerclage was also shown to increase the stability of osteosynthesis. Nevertheless, metal corrosion and the allergenic potency of steel remain problematic disadvantages of this method. A biomechanical study was carried out to evaluate titanium cable cerclage as an alternative supplement for plate osteosynthesis of a distal femoral two-part fracture. Materials and Methods: An unstable AO/OTA 32-A2.3 fracture was created in eleven pairs of nonosteoporotic human cadaver femora. All the samples were treated with polyaxial angular stable plate osteosynthesis. One femur from each pair was randomly selected for an additional fracture fixation with multifilament titanium cable cerclage. Stepwise cyclic axial loading was applied in a load-to-failure mode using a servohydraulic testing machine. Results: All specimens (mean age: 80 years; range: 57-91 years) withstood a cycling force of at least 1800 N. With a mean load of 2982 N (95% CI: 2629-3335 N), the pressure forces resulting in osteosynthesis failure were significantly higher in specimens with an additional titanium cerclage (Group 1) than in samples that were solely treated with plate osteosynthesis (Group 2) at 2545 N (95% CI: 2257-2834 N) (p = 0.024). In both groups, cutting out the distal screws at the condyle region, resulting in shearing of the distal fragment proximal to the fracture line, was the most frequent cause of construct failure. Among the specimens assigned to Group 1, 36% exhibited a specific fracture pattern, namely, a fracture of the dorsal buttress above the cerclage. Analysis of axial stiffness (p = 0.286) and irreversible deformity of the specimens revealed no differences between the groups (p = 0.374). Conclusion: Titanium cable cerclage application, as a supplement to an angular stable plate, resulted in an increased load to failure. In terms of stability, the use of this adjunct for fracture fixation of supracondylar two-part oblique femoral fractures might, therefore, be an option, especially in patients who are sensitive to nickel.

The effect of alkyl chain on the corrosion inhibition of benzyldimethylammonium chloride in acidic environments

Incorporating quaternary ammonium salts (QAS) during pickling is an efficient and eco-friendly approach to mitigating metal corrosion. This study investigated the effectiveness of Benzyldimethylhexadecylammonium chloride (HDBAC) and Benzyldimethyltetradecylammonium chloride (TDBAC) in inhibiting the corrosion of Q235 steel in H2SO4, utilizing electrochemical methods, atomic force microscopy (AFM), scanning electron microscopy (SEM), and theoretical calculations. The electrochemical results demonstrated that compared with the blank impedance value of 40.68Ω cm2, HDBAC and TDBAC at 5 mM concentration showed impedance values of 997.69Ω cm2 and 676.17 Ω cm2 at 298 K, indicating that they can effectively prevent the corrosion of Q235. SEM and AFM further showed the formation of a protective barrier film by HDBAC and TDBAC on the steel surface, effectively isolating it from the corrosive medium. Theoretical calculations further elucidated the mechanism by which these inhibitors create this protective barrier. The experiment also verified the hypothesis that the length of the hydrophobic chain of surfactants affects the adsorption behavior and the inhibition efficiency. When comparing their inhibitory effects at 5 mM concentrations, HDBAC exhibited superior performance (95.92 %) against Q235 in 0.5 M H2SO4, compared to TDBAC (94.09 %). These findings provide valuable insights for developing more effective and sustainable corrosion inhibitors for industrial applications.

Time dependent anti-corrosion and anti-scaling efficiency of polyepoxysuccinic acid inhibitor in simulated hard water

In this study, the time-dependent performance of a phosphorus-free corrosion and scale inhibitor primarily composed of polyoxyuccinic acid (PESA) and zinc salts was investigated in a laboratory-simulated hard water environment. Long-term static scale inhibition tests and corrosion rotation coupon tests were conducted under two temperature conditions, 45 °C and 80 °C, following established literature standards. Changes in water quality, scale morphology, metal corrosion status, and electrochemical impedance were monitored using calcium ion concentration analysis, optical microscopy imaging, X-ray diffraction (XRD), and electrochemical testing. The study revealed a progressive decline in the corrosion and scale inhibition efficiency of the phosphorus-free inhibitor in simulated hard water with calcium carbonate hardness levels of 300, 400, and 500 mg/L over time. Moreover, higher water hardness accelerated corrosion onset, suggesting that calcium carbonate deposition promotes metal corrosion under the experimental conditions. Density functional theory (DFT) calculations indicated that PESA chemically adsorbs onto both metal and calcite surfaces, underscoring its dual role in corrosion and scale inhibition. These findings underscore the intrinsic corrosion and scale inhibition capabilities of PESA, complementing its synergistic film-forming properties with Zn2+.

Three birds with one stone: ZIF-8@g-C3N4 nanosheets simultaneously enhance barrier property, active protection and UV aging resistance of epoxy coatings

In order to address the challenge of the epoxy coating’s limited ability to mitigate electrochemical reactions following metal corrosion as well as its susceptibility to degradation and aging under ultraviolet irradiation, ZIF-8 (ZIF=Zeolitic Imidazolate Framework) was modified on the surface of Graphite-like carbon nitride (g-C3N4) nanosheets by in-situ loading method to construct ZIF-8@g-C3N4 (ZCN) smart nanoparticles which exhibited an acidic pH response with releasing Zn2+ cations and imidazole molecules to achieve an 87.2 % corrosion inhibition efficiency on carbon steel within 5 h. Modified by ZCN, epoxy coating (ZCN/EP) retained high barrier property even after a 40-day immersion in a 3.5 wt% NaCl solution. Meanwhile, ZCN responded to pH changes from localized corrosion, releasing inhibitors and forming zinc oxide/zinc hydroxide and Fe-Im chelate to further impede corrosion progression. Furthermore, combining the ability to absorb and reflect/scatter UV radiation, ZCN provided excellent UV resistance for ZCN/EP coatings to maintain exceptional anti-corrosion after 300 h of UV exposure, as well as good surface characteristics and thermal–mechanical properties. This work provides a novel concept for developing long-lasting coatings with multifunctionality.

Effect of adsorption of two green biopolymers on the corrosion of aluminum in 1.0 M NaCl solution: Physicochemical, spectroscopic, surface and quantum chemical exploration

Although aluminum is an extremely versatile material and can be manufactured and used for a wide range of industrial purposes, it has a limited resistance to corrosion. Hence, the efficacy of two linear biopolymers, keratan (Ker) and chitosan (Chi), was explored, for the first time, as ecologically safe metallic corrosion inhibitors (CIs) for Al in 1.0 M NaCl solution at different temperatures. For performing this study, several experimental and theoretical methods were applied. By combining these methods, it was confirmed that the investigated biopolymers were set to be effective inhibitors for Al corrosion in 1.0 M NaCl solution. Using a 500 mg/L dose of CIs, inhibition efficiencies (% IEs) of 92.7 % and 86.4 % were achieved for Ker and Chi, respectively, indicating their strong adsorption on the metal surface. Thermodynamic and kinetic investigations signified that the adsorption was founed to be physical and obeyed the Langmuir isotherm. The kinetics and mechanism of Al corrosion as well as its inhibition by the tested biopolymers were inspected. The results demonstrated that these biopolymers behaved as mixed-type and interface-type inhibitors. To investigate the inhibition mechanism, theoretical quantum chemical methods were also applied. The experimental investigations were validated by theoretical computations.