Potentiodynamic Polarization Curves Research Articles

Corrosion Behaviour of Commonly Used Epoxy Resin Coated Agro Based Industrial Reinforcements

bstract: In this integrated study, the project aims to develop a novel hybrid green metal matrix composite using stir casting, reinforcing aluminum alloy with Waste materials such as Waste Carbonized Eggshells (WCE), Cow Dung Ash (CDA), Snail Shell Ash (SSA), and Bamboo Leaf Ash (BLA) The experiment incorporates various organic-inorganic mixed coatings, including vinyltrimethoxysilane (VMS), [3-(methacryloxy)propyl] trimethoxy silane (MPMS), and (3-glycidoxyproyl) trimethoxy silane (GPMS), combined with tetraethoxysilane (TEOS), to enhance corrosion resistance. Potentiodynamic polarization curves, SEM images, and salt spray tests are employed to assess coating durability against corrosion. Results indicate significant reductions in corrosion flow with VMS and MPMS coatings, particularly with a 15-20% TEOS ratio, showcasing optimal corrosion resistance against salt spray. This innovative approach combines material recycling and advanced coating techniques to produce a sustainable composite with improved mechanical properties and corrosion resistance.

Welding-induced corrosion and protective measures for clad rebars in neutral chloride environments.

Corrosion-resistant steel plays a vital role in marine steel structures. This study developed an SS304/HRB400 stainless-steel-clad rebar for application in a cross-sea bridge in Zhejiang Province. CO2 gas shielded welding was employed in the prefabricated steel structure, with SS304 steel as the welding wire. This study investigated the welding on the corrosion resistance of clad rebars and explored corrosion protection measures for welded joints.The results indicated that refined grains appeared in both stainless steel and carbon steel due to distinct dynamic recrystallization (DRX) during welding. The corrosion resistance, as determined by potentiodynamic polarization curve analysis of the material's interaction with the solution ranked as follows: clad rebar (polished) > clad rebar welding (CRW) > painting the clad rebar after welding (PCRW) > clad rebar (unpolished) > carbon-steel welding (CSW) > carbon-steel bar > cold spraying zinc after clad rebar welding (ZCRW). However, an accelerated corrosion test with four samples for 600s with a corrosion current of 0.8 A revealed minimal corrosion damage on zinc-coated surfaces. Hence, welding joints for clad steel structures are considered feasible and must be subject to cold zinc spraying after polishing to enhance their corrosion resistance.

Synergistic corrosion inhibition of rubber seed extract with KI on cold rolled steel in sulfuric acid solution

BackgroundPlant-based inhibitor has emerged an important topic owing to the combing merits of eco-friendly, low cost, rich natural resources as well as easy preparation. Rubber seed is the agricultural waste, and is mainly composed of oil and fatty acids those contain many polar oxygen atoms, and so it can be extracted to prepare the potential corrosion inhibitor. MethodsRubber seed extract (RSE) is prepared using reflux extraction method with the extracting solvent of ethanol aqueous solution. The synergistic inhibition effect of RSE and potassium iodide (KI) on the corrosion of cold rolled steel (CRS) in 0.50 M H2SO4 solution is firstly studied by weight loss, potentiodynamic polarization (PDP) curves and electrochemical impedance spectroscopy (EIS) methods. CRS surface was thoroughly characterized using metallographic microscope, scanning electron microscope (SEM), atomic force microscope (AFM), X-ray photoelectron spectroscopy (XPS) and contact angle measurements. FTIR, UV–vis and liquid chromatography mass spectrometry (LC-MS) compositional analysis of RSE were used to analyze the efficient components in RSE. Significant findingsThe results indicate that individual RSE or KI cannot function as a successful inhibitor to prevent CRS corrosion, but the mixture of RSE/KI performs better at inhibiting, with a maximal inhibition efficacy of up to 96.4% of 200 mg L−1 RSE/100 mg L−1 KI. The synergistic coefficient of the mixture is larger than 1, indicating that a true synergism. RSE/KI can drastically retard both cathodic and anodic processes, and interfacial capacitance falls as the charge transfer resistance of CRS/solution rises. It exhibits remarkable inhibition properties when the capacitor arc grows. There is only a small corrosion response in the inhibited media, as evidenced by the variations in electrical conductivity and ultraviolet spectrum before and after immersion. The hydrophilicity and surface roughness of CRS surface is dropped as a result of the introduction of RSE/KI. A series of metallurgical microscopy, AFM, SEM or contact angle tests indicate a synergistic inhibition effect is more pronounced for RSE/KI. XPS results clearly demonstrate that elements including Fe, S, N, and I are bonded to the surface of CRS. The primary ingredients of oleic acid, polyphenols, phenylpropanoids can also produce a strong synergism with KI.

Understanding the effect of microstructure and composition on localized corrosion susceptibility of 6xxx aluminum alloys

The corrosion performance of 6xxx series Al alloys has been found to depend on small changes in composition and microstructure. The corrosion behaviors of three aluminum alloys, AA6111, AA6451, and AA6016, were investigated. AA6111, containing primarily α (Al15 (Fe,Mn)3Si2) intermetallic particles (IMPs), and AA6016, containing primarily β (Al8Fe2Si) IMPs, exhibited the best and the worst overall corrosion performances, respectively, as indicated by the extent of corrosion in exposure tests. However, this ranking was not predicted by the standard interpretation of potentiodynamic polarization curves measured on the alloys. The corrosion susceptibilities of the three alloys were further investigated by evaluating the electrochemical behavior of the component phases separately. Bulk analogs of the component phases were fabricated using standard alloy casting techniques. The fabricated bulk analogs of α and β IMPs, as well as the three alloy matrix phases, were tested using either macrocell or microcell testing. An explanation for the alloy performances was developed by combining the behavior of the component phases.

Characteristics of hydride electrodes using Mg-Ti-Ni-Co-Al-based alloys synthesized by mechanical milling

For Ni-MH batteries, crystalline Mg-based alloys such as MgNi, Mg2Ni, REMg12, and La2Mg17 are regarded as hopeful negative electrode materials. Even though these alloys are inexpensive and have promising discharge capacity, they hardly ever electrochemically absorb or desorb hydrogen at room temperature. In this paper, the MgNi-based Mg50-xTixNi45Al3Co2 (x = 0, 1, 2, 3, 4) alloy electrodes were fabricated. The surface of the as-cast alloys was modified by mechanical Ni coating. The nanocrystalline and amorphous Mg50-xTixNi45Al3Co2 (x = 0, 1, 2, 3, 4) + 50 wt.%Ni alloys for Ni-MH batteries were prepared using mechanical ball milling. The effects of Ti content and ball milling time on the structure and electrochemical hydrogen storage properties of the alloys were investigated. The electrochemical testing reveals that the as-milled alloys can electrochemically absorb and desorb hydrogen well at room temperature. Without any activation, the milled alloys can achieve maximum discharge capacity in the first cycle. With the extension of ball milling time and the increase of Ti content, the cycle stability and discharge capacity of the alloys are significantly enhanced. The electrochemical impedance spectrum, high rate discharge ability, potentiodynamic polarization curve, and potential-step measurement all indicate that the electrochemical kinetics of the prepared alloys initially increase and subsequently decrease with the increase of Ti content, while significantly improve with the prolongation of milling time.

Testing the inhibition efficiency of the castor oil leaf as corrosion inhibitor of mild steel in H2SO4

This study focused on the testing of castor oil leaf as corrosion inhibitor of mild steel in H2SO4. It involved the examination of the dynamics of molecular forces at the inhibitor and mild steel interface. Findings of the study will promote industrial diversification of castor oil leaf. On the experiment, bio-molecular compounds of the leaf were identified by gas chromatography mass spectrophotometer. Then, gravimetric and potentiodynamic polarization techniques were employed, where the efficacy and type of the inhibitor were determined. Considering the gravimetric process, factors of inhibitor concentration (0.2 g/L - 1.0 g/L), temperature (303 K – 333 K) and time (8 hrs – 24 hrs) were considered, with the inhibitor efficiency as the response. The efficiency was determined and optimized using response surface methodology (RSM) and artificial neural network (ANN). On the other hand, potentiodynamic polarization process was used to identify the type of inhibitor. Adsorption quantities were ascertained through the subjection of the experimental raw data to various adsorption isotherms. The analyses showed that castor oil leaf contains methyl nicotinate and pyridine-4-carbohydrazide. The bio-molecular compounds possess heteroatoms (N, S and O), signifying strong corrosion inhibitive tendencies. High efficiency (96.25 %) was obtained, with ANN having better prediction capability than the RSM. Potentiodynamic polarization curves revealed castor oil leaf as mixed-type inhibitor. On the adsorption phenomenon, the process of the inhibition was best fitted by Frumkin isotherm, revealing physical adsorption mechanism of Gibb’s free energy less than -40 kJ/mole. As a mixed-type inhibitor, castor oil leaf should be applied for mitigation of anodic and cathodic corrosion.

Effect of recrystallization degree on properties of passive film of super ferritic stainless steel S44660

Abstract The effect of the recrystallization degree on the properties of passive films formed in 0.1 M HNO3 solution for super ferritic stainless steel S44660 was examined in this study. The initial specimens, in their cold-rolled state, showed a high dislocation density, as observed through electron backscatter diffraction (EBSD) experiments. Analysis of potentiodynamic polarization (PDP) curves and electrochemical impedance spectroscopy (EIS) measurements suggested that with the increase of recrystallization degree, the corrosion current density reduced and the corrosion potential increased. As revealed by Mott–Schottky analysis, the passive film showed a dual structure of n-type and p-type semiconductors, with the carrier density of the passive film decreasing as the recrystallization degree increased. X-ray photoelectron spectroscopy (XPS) provided insights into the film composition, indicating that the Fe2O3 and Cr2O3 content, which improved the stability of the passive film, increased with the degree of recrystallization. In summary, the increase in recrystallization degree reduced the number of defects in the microstructure, thereby creating favorable conditions for the formation of highly protective passive films. The passive film formed after complete recrystallization exhibited enhanced corrosion resistance.

In-Depth Insight into Corrosion Inhibition Performance of Sweet Potato Leaf Extract as a Green and Efficient Inhibitor for 6N01 Al Alloy in the Seawater: Experimental and Theoretical Perspectives.

Corrosion protection of metal has become an important and urgent topic, which requires the development of an inexpensive, environmentally friendly, and highly efficient corrosion inhibitor. Herein, a sweet potato leaf extract (SPL) was obtained by a simple water-based extraction method and then as a green corrosion inhibitor for 6N01 Al alloy in the seawater was well investigated by the weight loss method and various electrochemical tests. Fourier transform infrared (FT-IR) and ultraviolet-visible (UV-vis) spectroscopies were carried out to investigate the compositions of SPL. The findings from the potentiodynamic polarization (PDP) curves suggest that SPL functions as a typical mixed-type corrosion inhibitor. Notably, the maximum corrosion inhibition efficiency reaches 94.6% following a 36 h immersion period at 25 °C. The adsorption behavior of SPL on the Al alloy surface belongs to the Langmuir adsorption isotherm. The Gibbs free energy value illustrates that the adsorption of SPL contains both physisorption and chemisorption. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) indicate that SPL is firmly attached to the Al alloy surface by making a protective layer, which can effectively inhibit the corrosion of the Al alloy in the seawater. Furthermore, quantum chemical calculations were applied to validate the chemical adsorption and elucidate the relationship between the electronic structure of the active components in SPL and their effectiveness in corrosion inhibition.

Characterization of cosputtered (TiZrHfY)Nx films

Medium-entropy TiZrHfY alloy films and corresponding nitride (TiZrHfY)Nx films were fabricated through cosputtering. The Ti0.24Zr0.23Hf0.27Y0.26 film had the form of a hexagonal close-packed (HCP) solid solution with a mixing enthalpy of 9.09 kJ/mol, mixing entropy of 11.50 J/mol·K (1.38 R), atomic size difference of 7.72 %, and valence electron concentration of 3.73. Moreover, this film had a hardness of 6.0 GPa and an elastic modulus of 106 GPa. (TiZrHfY)Nx films with various stoichiometric ratios (x) were fabricated by adjusting the reactive gas flow ratio fN2 [N2/(N2 + Ar)] in the range 0.1–0.7. Adding N to the TiZrHfY matrix resulted in a change of phase from an HCP structure to a face-centered cubic phase. The (Ti0.23Zr0.18Hf0.24Y0.35)N0.71 film (with fN2 = 0.2) exhibited the most favorable mechanical properties, having a hardness of 19.1 GPa and an elastic modulus of 244 GPa. Moreover, the film had the highest critical loads (LC3 = 46.6 N) among the films analyzed in the scratch test. The anticorrosive properties of the TiZrHfY and (TiZrHfY)Nx films were evaluated using potentiodynamic polarization curves, obtained in 3.5 wt% NaCl aqueous solution. High polarization resistance of 1.1 × 106 Ω·cm2 was obtained for the (Ti0.23Zr0.18Hf0.24Y0.35)N0.71 film, which was 145 times higher than that of the bare SUS420 substrate. The (Ti0.23Zr0.18Hf0.24Y0.35)N0.71 film had the most favorable mechanical and anticorrosive properties of the surveyed (TiZrHfY)Nx films.

Electrochemical Studies of The Corrosion Resistance of Bismuth Titanate Thin Films Deposited by RF Sputtering

Thin films of bismuth titanate were grown on stainless steel (316L) and titanium alloy (Ti6Al4V) substrates using the magnetron sputtering technique. The surface morphology of these films was observed with a scanning electron micrograph (SEM). The electrochemical studies used to evaluate the corrosion resistance of the substrate-coating set were the potentiodynamic polarization (Tafel) tests and electrochemical impedance spectroscopy (EIS), both done in a solution of NaCl (3%) as an electrolyte. The SEM showed that the morphology of the coatings grown on a titanium alloy Ti6Al4V substrate was generally homogeneous with a smooth surface but with unmelted material in some regions, while the morphology of the thin films grown on stainless steel 316L was mainly granular, with the presence of a few holes or craters. The potentiodynamic polarization curves showed that the corrosion resistance of the coated samples was better than that of the bare substrate because the corrosion current obtained from the coated samples was lower by two orders of magnitude than that exhibited by the uncoated substrates, and in addition, the corrosion potential of the coated samples was greater than that of the bare substrate. The EIS test showed the presence of a passive thin film of titanium oxide on the titanium alloy substrate.

Exploring the efficacy of Congo Red dye as a corrosion inhibitor for aluminum in HCl solution: An interdisciplinary study with RSM modeling and theoretical simulations

This study investigates Congo Red Textile Dye (CRD) as a corrosion inhibitor for aluminum in a 1.0 mol/L hydrochloric acid solution. Utilizing a comprehensive suite of analytical techniques, including gravimetric analysis, scanning electron microscopy (SEM), ultraviolet–visible spectrophotometry (UV–Vis), Electrochemical Impedance Spectroscopy (EIS), and Potentiodynamic Polarization curves (PDP), we assessed CRD’s adsorption mechanism and its corrosion inhibition effectiveness. Significant corrosion mitigation was observed, with the efficiency of inhibition EI (%) increasing alongside CRD concentration, achieving a maximum efficiency of 87.5 %. This enhancement in EI (%) decreases with rising temperatures, assessed across a range from 298 to 323 K. Response surface methodology (RSM) and central composite design (CCD) were employed for accurate corrosion rates (Vcorr) and EI (%) prediction. Additionally, theoretical analysis was performed using global and local reactivity descriptors along with molecular dynamics (MD) simulations. Theoretical results confirmed the widespread presence of nucleophilic and electrophilic sites, along with a strong affinity for the Al surface, suggesting CRD’s potential for enhancing corrosion resistance. This study proposes a potential pathway for the valorization of Congo Red dye, utilizing concentrations within non-toxic thresholds, thereby aligning with environmental safety and industrial application considerations.

Стойкость против питтинговой коррозии как критерий безопасности эксплуатации металлического оборудования

Pitting corrosion is hazardous for personnel of chemical plants operating with tanks, reactors, and pipelines. Pitting is a pinpointed corrosive damage rapidly penetrating a metal and causing its through-perforation. Chemical and thermal burns and poisoning of personnel are also potential. When designing the equipment, it is required to select materials able to resist pitting corrosion in the operational medium. Quick methods of pitting resistance of material include the comparison of critical potentials determined by potentiodynamic polarization curves. The potential of the studied sample is given a value equal to the corrosion value that is increased at the rate of 0.2–2 mV/s. At the same time, values of current density are registered. The gradual increase of current density is followed by its decrease, and the metal turns to a passive state. With a certain value of pitting formation potential, the current density increases acutely; and pittings are formed on the metal surface. When the potential is decreased, current density within a certain range of values remains relevant to the current density at the pitting formation potential but then decreases to the values relevant to dissolution in a passive state. This occurs at the re-passivation potential. Earlier, values of potentials of pitting formation and corrosion were compared. Later, it was proved that the evaluation of the pitting resistance of metals based on the comparison was not correct as pittings could also be formed at the potentials lower than the pitting formation potential. The correct evaluation of metal pitting resistance can be obtained based on the comparison of re-passivation and corrosion potentials. Until now, however, the pitting formation potential has been used for the evaluation. Based on the experimental potentiodynamic polarization curve of stainless steel Х20Н6Г11 and the results of corrosion tests, it has been established that metal corrodes at potentials above the re-passivation potential but lower than the pitting formation potential. When potentials are lower than the re-passivation potential, pittings are not formed.

Мырыш электродын өндірістік айнымалы токпен натрий хлориді ерітіндісінде поляризациялау арқылы мырыш оксидін алу

The purpose of the work is to dissolve the zinc electrode during polarization with an alternating current with a frequency of 50 Hz and to obtain zinc oxide. It is shown that the pre-recorded anode-cathode cyclic potentiodynamic polarization curves allow to predict to a certain extent the processes occuriing on the zinc electrode during alternating current polarization. It has been established that when two zinc electrodes are polarized in sodium chloride with an alternating current with a frequency of 50 Hz, they do not dissolve, but when one electrode is replaced with a titanium one, zinc dissolves intensively with the production of zinc hydroxide. It is shown that the rate of zinc dissolution directly depends on the current density at the titanium electrode. When the values of the current density on the titanium electrode change in the range of 5-10 kA/m2, the zinc dissolution current efficiency exceeds 100%. Based on the results of the research, it was established that zinc (II) hydroxide is produced during electrolysis, and zinc oxide can be obtained by dehydration. The composition of the resulting compound was identified by X-ray phase and elemental analyses

Enhancing steel corrosion resistance in 1.0 M HCl medium through the synthesized and characterized mixed pyrophosphates BMnP2O7 (B = Ni, Co, and Cd)

In this study, we synthesized three diphosphate materials NiMnP2O7, CoMnP2O7, and CdMnP2O7 intended for use as corrosion inhibitors for carbon steel. The crystallinity of the obtained compounds was analyzed using X-ray diffraction (XRD), and a vibrational analysis was carried out by infrared (IR) and Raman (Ra). The corrosion inhibition properties of steel with these materials in 1.0 M HCl solution were investigated using three important techniques. The electrochemical parameters were obtained via electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves (PDP) and the surface of the substrate was analyzed, using the scanning electron microscopy (SEM). Our findings indicate that the optimal concentration for NiMnP2O7, CoMnP2O7, and CdMnP2O7 was 10−3 mol/L, with inhibition efficiencies reaching to 87.5 %, 91.04 %, and 92.22 %, respectively. These phosphates also act as a mixed-type inhibitors, imparting high resistance to corrosion, and their inhibition efficiency (η%) increased with the augmentation of the inhibitor concentration. The scanning electron microcopy (SEM) images revealed that the inhibitors form a protective layer against acid attack, preventing carbon steel from being destroyed.

Effect of Ce replacing La on the electrochemical performance of amorphous grain boundaries Mg-Ni-based materials

Aiming at enhancing the electrochemical characteristic of RE-Mg-based composite, the partial substituting La with Ce experiment in the composites was conducted, and the surface modification treatment of the alloys was performed by mechanical coating Ni. By means of mechanical trituration, The La10-xCexMg80Ni5 (x = 0–2) + y wt% Ni (y = 50–200) compound materials which have the structures of nanocrystalline and amorphous were synthesized. In order to make sense of the principle action of Ce and Ni elements in structural and electrochemical properties of the material, some deep research were carried out. According to the final results, the as-milled composites have the electrochemical hydrogen absorption and hydrogen desorption abilities at room temperature. Having no use for activation, the as-milled composites can reach the maximum discharge capacities when the first cycling was carried out. With the Ni value x changed from 50 to 200, the discharge capacity was varied from 70.5 mAh/g to 902.1 mAh/g; moreover, the capacity retention rate at 20th cycle (S20) and high rate dischargeability (HRD) of the (x = 0) composite were heightened from 67.2 % to 82.3 %, from 50.6 % to 55.7 % respectively. The composites' (y = 100) discharge capacity has a maximum value 118.5 mAh/g when the Ce value x is 1. The capacity retention rate (S20) is enhanced from 53.3 % to 68.5 % by lifting Ce content from x = 0 to x = 2. what's more, the high-rate discharge ability (HRD), the electrochemical impedance spectrum (EIS), potentiodynamic polarization curves, and potential-step measurements all intimate that substituting La with Ce clearly promotes the composites' electrochemical kinetic properties, but maximum values emerge only when the x value is 1.

Inhibition of corrosion on API 5L X52 pipeline steel in acid media by Tradescantia spathacea.

The concentration effect of Tradescantia spathacea (T. spathacea) as corrosion inhibitor of API 5L X52 steel in 0.5M of H2SO4 was studied here through electrochemical and gravimetric techniques. To achieve it, samples of the material were prepared to be submitted to each of the tests. Results from electrochemical impedance spectroscopy (EIS) showed that there was an optimum concentration of the inhibitor in which is reached the maximum inhibition efficiency, displaying the best inhibition characteristics for this system with a maximum inhibition of 89% by using 400ppm. However, the efficiency decreased until 40% when the temperature was increased to 60°C. Potentiodynamic polarization curves (PDP) revealed that some of the present compounds of T. spathacea may affect anodic and cathodic process, so it can be classified as a mix-type corrosion inhibitor for API 5L X52 in sulfuric acid. Also, this compound followed an adsorption mechanism; this can be described through a Frumkin isotherm with an adsorption standard free energy difference (ΔG°) of -56.59kJmol-1. Metal surface was studied through scanning electron microscope, results revealed that by adding inhibitor, the metal surface is protected; also, they evidenced low damages compared with the surface with no inhibitor. Finally, Tradescantia spathacea inhibited the corrosion process with 82% efficiency.

Corrosion Behavior of Carbon Steel in LiCl/H2O Mixtures

The corrosion behavior of 1018 carbon steel in LiCl/H2O mixtures has been evaluated by using potentiodynamic polarization curves, electrochemical noise and electrochemical impedance spectroscopy techniques. Two different concentrations of LiCl were employed, namely 35 and 40 wt. %, and the testing temperatures included 25, 35 and 70 °C. It was found that the steel showed a passive zone; the corrosion current density value increased with an increase in the solution temperature and concentration. The pitting potential value decreased with an increase in the testing temperature and the solution concentration. The corrosion process was under charge transfer control. This mechanism was unaltered either by the solution temperature or concentration. The charge transfer resistance value decreased with an increase in both the solution temperature and concentration. A localized, pitting type of corrosion dominated the corrosion morphology at 25 and 35 °C, whereas at 70 °C, the main type of attack was a mixed type of corrosion.

An electrochemical method for the regeneration of trivalent iron to increase the efficiency of in-situ leaching of uranium

Due to the increasing demand for electricity with the development of production and general infrastructure, increasing the production of uranium as an economically and environmentally efficient source of energy is an urgent problem. The purpose of this study is to develop an electrochemical method for the regeneration of iron (III) ions used as a uranium oxidizer in the process of in-situ leaching of uranium minerals with sulfuric acid solutions. Methods. The mechanism of reactions in the iron (II)-iron (III) redox system was studied by recording potentiodynamic polarization curves and conducting electrolysis of the oxidation of divalent iron ions under galvanostatic conditions. Results and discussion. Cathode-anodic and anodic-cathode cyclic polarization curves taken on platinum electrodes showed that the redox reactions of iron ions are reversible and these reactions occur at a slight overvoltage. The influence of the main electrochemical parameters (current density, concentrations of iron (II) ions and sulfuric acid) on the oxidation of divalent iron ions was studied for the first time using granular anode electrodes, the electrode spaces of which are separated by an anionite membrane. It has been found that the use of granular graphite electrodes in the oxidation divalent iron ions increases the current output by more than 2 times compared to a plate graphite electrode. Conclusion. According to the results of the study, it was noted that under optimal conditions, the current output of the oxidation of divalent iron ions exceeds 90%. Extensive research has shown that trivalent iron ions, widely used in the in-situ leaching process for uranium production, can be regenerated by electrochemical methods.

Exploring sustainable corrosion inhibition of copper in saline environment: An examination of hydroquinazolinones via experimental and ab initio DFT simulations

Copper's potential in various applications is constrained due to environmental degradation, particularly in high-salinity environments, representing a sustainability concern. Herein, two novel hydroquinazolinones, namely 1-((4-hydroxynaphthalen-1-yl)methyl)-2-phenyl-2,3-dihydroquinazolin-4(1H)-one (DQ-H) and 1-((4-hydroxynaphthalen-1-yl)methyl)-2-(p-tolyl)-2,3-dihydroquinazolin-4(1H)-one (DQ-CH3), were analyzed for their ability to inhibit copper corrosion in a 3.5 % NaCl solution. The compounds, characterized by 1H and 13C NMR, were evaluated via potentiodynamic polarization curves, electrochemical impedance spectroscopy, and weight loss measurements. Comprehensive analyses utilizing scanning electron microscopy, Fourier Transform Infrared, and UV–vis spectroscopy have revealed insights into the surface morphology and the interactive nature of inhibitor molecules with the copper surface. Our findings highlight the formation of a strong, sustainable inhibitor film on the copper surface due to the addition of hydroquinazolinones, thereby exhibiting an enhanced polarization resistance and decreased double-layer capacitance. Both DQ-H and DQ-CH3 demonstrated a considerable inhibition effect, with efficiencies of 92 % and 94 % respectively, illustrating their potential for sustainable copper protection. Electrochemical impedance spectroscopy (EIS) results indicated a significant increase in polarization resistance from 605.7 (blank) to 9403 and 12861 Ω cm2, after the addition of DQ-H and DQ-CH3, respectively. Furthermore, the adsorption attributes of the compounds on the Cu(111) surface were examined using first-principles density functional theory simulation, revealing several covalent bonds formation. Our work aims to contribute to sustainability efforts in materials science by offering a corrosion-protective solution that is less harmful to the environment and more efficient in preserving copper's durability, particularly in saline environments.

Electrodeposition of Zn[sbnd]Co alloy coatings on carbon steel and their corrosion resistance

The development of ZnCo alloys appeared as alternative for obtaining layers more resistant than the conventional zinc with a minimum increment of cost. The aim of this work is to study the electrodeposition mechanism of the ZnCo alloy on SAE 1020 carbon steel by cyclic voltammetry using two baths with different [Zn2+]/[Co2+] concentration ratios and also to evaluate the corrosion resistance in 0.1 mol L−1 NaCl of electrodeposits obtained potentiostatically using electrochemical techniques as electrochemical impedance spectroscopy, linear polarization resistance and potentiodynamic polarization curves. The voltammograms showed two anodic peaks attributed to dissolution of zinc rich ƞ-phases and cobalt, and a cathodic peak related to ZnCo alloy deposition. The nucleation mechanisms were examined by fitting the experimental data (chronoamperometry) into the Scharifker and Hills nucleation models. Scanning electron microscopy (SEM) showed that the electrodeposits obtained for the [Zn2+]/[Co2+] 9:1 ratio presented a structure in the form of hexagonal platelets in comparison to the electrodeposits with [Zn2+]/[Co2+] 12:1 ratio, which presented cauliflower-shaped structures. On the other hand, the electrochemical techniques proved that the electrodeposits obtained for the [Zn2+]/[Co2+] 9:1 ratio at potential of −1450 mV presented the best anticorrosive properties. Structural and chemical characterization of coatings was accomplished by XRD and XRF.