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Zinc-substituted cobalt ferrites were obtained by a green method using a black grape extract as a reductant and fuel. XRD analysis confirmed the spinel structure of the synthesized ferrites. An increase in the lattice constant is explained by increased Zn content. SEM analysis confirmed changes in surface morphology, whereas FTIR spectra demonstrated the presence of organic species in the samples, which originated from grape extract. The content of Co(II) ions in octahedral sites as a function of the ratio between Fe(III) ions in A- and B-sites was calculated from Mössbauer data. pHPZC rose from 7.85 to 8.13 with an increase in zinc content, indicating a positive charge of the adsorbent surface at natural pH. The adsorption–catalytic properties of the spinel samples were investigated in terms of Congo Red (CR) dye removal. The mechanism of CR adsorption on the ferrite surface includes electrostatic and donor–acceptor interactions with the adsorbent surface. Furthermore, the sample with x(Zn) = 0.4 exhibited the highest degradation rate constant k = 0.102 min−1 in the peroxide oxidation of CR, whereas the sample with x(Zn) = 1.0 exhibited the highest adsorption capacity. The electron transfer between ferrite samples and hydrogen peroxide was evidenced using electrochemical tests. The green-synthesized Co-Zn ferrites demonstrate a big potential as adsorbents/catalysts for water treatment. [ABSTRACT FROM AUTHOR]

The study involved the preparation of mixtures of phytic acid ionic liquid and water, which were analyzed for their rheological, frictional, and electrochemical properties. The viscosity and friction characteristics of the mixtures are significantly affected by the water content. Mixtures with low water content (below 30%) result in low friction and negligible wear because of the generation of a close adsorption film and high viscosity. Especially, steel tribo-pairs lubricated with mixtures containing 25% water exhibited friction coefficients lower than 0.06. However, when the water content exceeds 35%, the friction coefficient increases dramatically, and the tribo-surface suffers from severe corrosive wear due to the predominance of tribocorrosion in the frictional properties. These results were confirmed through XPS and electrochemical testing. [ABSTRACT FROM AUTHOR]

Temperature significantly affects the galvanic corrosion behavior between carbon fiber reinforced plastic (CFRP) and carbon steel. The corrosion rate of steel components in bridges may increase at high temperatures during summer. To examine the impact of solution temperature on the galvanic corrosion between CFRP and carbon steel, electrochemical tests were conducted at different temperatures. The open circuit potential results and potentiodynamic polarization results indicated that the presence of carbon fiber to carbon steel led to increased potential and accelerated corrosion rates. Subsequently, the temperature-promoting factor was used to predict the corrosion rates of steel with galvanic corrosion based on the Arrhenius equation. Finally, the limitations of the temperature-promotion factor were analyzed theoretically. [ABSTRACT FROM AUTHOR]

The erosion-corrosion mechanism in rotary flowing seawater is hugely complicated due to the multiscale coupling processes of particle-surface impact, ion mass transfer, and interface electrochemistry. Therefore, developing erosion-corrosion resistant material and exploring the synergistic mechanism between sand erosion and electrochemical corrosion is vital. This study conducted the erosion-corrosion test on Ni2FeCrMo0.2 high-entropy alloy under the particle-seawater flow. Based on a coupled analysis of multi-component weight loss, electrochemical behavior, and microscopic damage morphology, the multiscale coupling processes of sand transportation, particle-surface impact, ion mass transfer, and interface electrochemistry were revealed. The present study found that with the increase of sand size, the energy carried by the particles promoted impact erosion. Additionally, particle movement enhanced ion mass transfer through turbulent effects, and the impact behavior disrupted the passivation film to promote electrochemical processes by reducing the thickness of the passivation film, leading to an increase in the erosion-corrosion rate. However, when the particle size continued to increase to a certain extent, the impact frequency decreased, reducing the erosion-corrosion rate. As the sand size grew, the dominant damage mechanism transitioned from pure corrosion (100 μm) to synergistic effects (200 μm, 400 μm) and then to pure erosion (800 μm). This study provides an in-depth understanding of the erosion-corrosion mechanism in seawater from the perspective of particle-ion-fluid-surface interaction by multi-element characterization.

Nowadays, a good corrosion resistance of lightweight steel is demanded for its application. However, due to the high contents of Mn and C, which are always corrosion-susceptible elements in steels, the conventional lightweight steel is not desirable for this mission. Although Cr is widely believed to be a common alloying element to improve the corrosion resistance of most steels, it is considered to be ineligible using in the lightweight steel due to the relatively high content of C. This is because the trade-off between corrosion resistance and mechanical properties by alloying Cr. In recent years, the rapid developments of additive and coating manufacturing have provided new possibilities for both the Cr alloying and microstructural modulation to improve corrosion resistance of lightweight steel. In this case, to design a certain chemical composition using in additive and coating manufacturing, it is interesting to clarify the effects of Cr alloying on the corrosion resistance of lightweight steel. To reveal it, in the present work, the Fe–Mn–Al–Cr–Si–Mo–C lightweight steel alloyed with Cr contents of 4 wt%, 8 wt% and 12 wt% are prepared. The corrosion resistances and mechanisms of Cr-alloyed lightweight steels in 3.5 wt% NaCl solution are investigated by electrochemical and immersion tests. The present work may provide new insights for the composition design of lightweight steel, especially for the directions of additive and coating manufacturing.

Corrosion is a pervasive phenomenon affecting materials across a multitude of scales, from the atomic to the macroscopic. This review paper presents a comprehensive examination of the methodologies employed in the analysis of magnesium corrosion, including electrochemical, non-electrochemical and analytical approaches, emphasizing the need for a diverse array of analytical tools to understand the complex interplay between corrosion, microstructure, and the dissolution mechanisms of magnesium alloys. The research showcases the utility of specific tools like SEM/EDS and SKPFM for targeted site analysis, while XPS and FTIR provide a broader perspective on specimen surfaces. The paper also discusses the value of in-situ analysis techniques, which allow for the real-time observation of corrosion processes, offering a dynamic view of the emergence and evolution of corrosion products. These in-situ methods stand in contrast to ex-situ analyses, which only permit post-experimental evaluation. By highlighting the capabilities of various analytical tools, from those that reveal surface layer details to those that probe deeper structures, and from those that detect primary elements to those that trace minute quantities of impurities, this study underscores the intricate nature of corrosion and the critical role of advanced analytical techniques in fostering a deeper understanding of material degradation. The findings advocate for the increased application of in-situ analysis in magnesium corrosion research, as it provides a more immediate and accurate depiction of corrosion dynamics, potentially leading to more effective corrosion prevention and control strategies.

Mooring chains are key components of offshore floating photovoltaic systems. Although their service safety is often affected by the harsh service environment, the influence of surface roughness on their corrosion resistance is not clear. This study investigated the corrosion behavior of mooring chain steel using cyclic salt-spray corrosion and electrochemical tests. Scanning electron microscopy, energy-dispersive spectrometry, optical profilometry, and other analytical techniques were used to study the composition and morphology of the corrosion products. The corrosion behavior was studied by electrochemical polarization curves, alternating current impedance spectroscopy, and X-ray photoelectron spectroscopy. The results show that the salt-spray corrosion resistance of mooring chain steel significantly improved with the reduction in specimen surface roughness, and the number and depth of corrosion pits were reduced. Mass loss after 24 h of salt-spray corrosion was exponentially related to initial roughness ( Ra ). Improved surface roughness significantly increased the pitting potential of the specimens, widened the passivation range, and enhanced the repassivation capability, thus significantly improving the pitting resistance. The pitting potential is linearly related to the initial roughness of the specimen. The oxide contents of Fe, Mo, and Si in the passivation film tended to increase with a smoother surface, which contributes to its densification. This effectively blocks chloride ion attack, thus improving the corrosion resistance of the mooring chain steel. [ABSTRACT FROM AUTHOR]

• The paper provides a detailed review of different methodologies for analyzing Mg corrosion, including electrochemical, non-electrochemical, and analytical techniques. • A diverse set of analytical tools is used in Mg corrosion research to explore the interplay between corrosion, microstructure, and material dissolution mechanisms. • Tools like SEM/EDS, SKPFM, and TEM offer site-specific analysis, while XPS, FTIR, and BIB provide a more general view of the specimen surfaces. • Instruments such as TKD, AES, and ToF-SIMS/NanoSIMS are specialized for surface layer analysis, contrasting with CT tomography and SEM that reveal details from within the specimen. • Increasing significance of in-situ analysis in Mg corrosion research is highlighted, enabling the real-time observation of corrosion processes and the identification of initial corrosion products as they emerge. Corrosion is a pervasive phenomenon affecting materials across a multitude of scales, from the atomic to the macroscopic. This review paper presents a comprehensive examination of the methodologies employed in the analysis of magnesium corrosion, including electrochemical, non-electrochemical and analytical approaches, emphasizing the need for a diverse array of analytical tools to understand the complex interplay between corrosion, microstructure, and the dissolution mechanisms of magnesium alloys. The research showcases the utility of specific tools like SEM/EDS and SKPFM for targeted site analysis, while XPS and FTIR provide a broader perspective on specimen surfaces. The paper also discusses the value of in-situ analysis techniques, which allow for the real-time observation of corrosion processes, offering a dynamic view of the emergence and evolution of corrosion products. These in-situ methods stand in contrast to ex-situ analyses, which only permit post-experimental evaluation. By highlighting the capabilities of various analytical tools, from those that reveal surface layer details to those that probe deeper structures, and from those that detect primary elements to those that trace minute quantities of impurities, this study underscores the intricate nature of corrosion and the critical role of advanced analytical techniques in fostering a deeper understanding of material degradation. The findings advocate for the increased application of in-situ analysis in magnesium corrosion research, as it provides a more immediate and accurate depiction of corrosion dynamics, potentially leading to more effective corrosion prevention and control strategies. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, the 1,2,4-triazole and its derivatives were used as target corrosion inhibitors, the corrosion inhibition of 1,2,4-triazole (TAZ), 3-amino-1,2,4-triazole (ATA) and 3,5-diamino-1,2,4-triazole (DAT) in 3.5 wt.% NaCl solutions for aluminum brass (HAl77-2) are reported. The inhibition properties and mechanism were investigated by weight loss tests, electrochemical tests (electrochemical impedance spectroscopy and linear polarization resistance tests), surface characteristic analysis (scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) tests), and quantum chemistry calculations. The results showed that TAZ, ATA, and DAT effectively inhibited the corrosion of HAl77-2. The maximum inhibition efficiencies of the three corrosion inhibitors were 84.4 %, 86.4 %, and 87.1 %, respectively. The adsorption processes followed the Langmuir adsorption isotherm model and were of mixed type, i.e., both physisorption and chemisorption. SEM and EDS tests confirmed the effective adsorption of the TAZ, ATA, and DAT on the HAl77-2 surface. The results of quantum chemistry calculations were consistent with the electrochemical test results.

In this study, the effects of substrate materials and electrodeposition parameters on the hydrogen evolution reaction (HER) of Ni–Cu–Fe coatings were studied. For this purpose, different materials, including carbon steel (CS), stainless steel 304 (SS), and pure commercial graphite (G) were used as substrates, while the coating process was done in both modes of constant current density (CC) and variable current density, the latter to produce a functionally-graded (FG) coating. Microstructural investigations were done by using scanning electron microscopy, while the HER behavior was analyzed by electrochemical tests, including cyclic voltammetry (CV), linear scanning voltammetry (LSV), and electrochemical impedance (EIS) measurements. The morphology of the produced Ni–Cu–Fe coatings was completely affected by the coating parameters in the deposition bath and the type of substrates. In samples with micro/nano-cone morphology, deposited at a constant current density of 2.5 A/dm2, better HER behavior was obtained due to the highly effective surface and easier separation of hydrogen bubbles. Besides, the best electrocatalytic activity and the lowest overpotential (110 mV at 10 mA/cm2 in CC mode) were related to the samples coated on G. The proper selection of the substrate material plays an important role in improving the electrocatalytic behavior of composite coatings. • The constant current and functionally-graded Ni–Cu–Fe coating were successfully produced. • The morphology of the coatings was completely affected by the coating parameters and the type of the substrates. • The minimum overpotential was related to the G/Ni–Cu–Fe (CC) sample. [ABSTRACT FROM AUTHOR]

This work describes how to easily make NiO hollow sphere composites using waste sugarcane bagasse for use in supercapacitor applications. NiO hollow spheres (NOHSs) nanomaterialis effectively synthesized through the nano carbon sphere (CS) template. A core-shell structure was created on the carbon sphere's surface by NiO nanoparticles that were several nanometers in size. The structural and morphological of the synthesized materials were investigated by X-ray diffraction (XRD) and Scanning electron microscope (SEM). The energy-dispersive X-ray spectroscopy (EDS) was used to confirm the presence of the elements in NOHS. The electrochemical behaviour of hierarchical CSs and NOHSs electrode was examined through cyclic voltammetry (CV), Galvanostatic charge/discharge (SC) and electrochemical impedance spectroscopy (EIS). In GCD analysis, NOHSs electrode showed a concentrated specific capacitance (Csp) of 913.79 F/g at 5 A/g current density. The porous conductive carbon with macro pores that speeds up the transit of electron and electrolyte ions causes noticeably better capacitive behavior. [ABSTRACT FROM AUTHOR]

To reveal the influence of joint type and epoxy-coated steel bar surface damage on the durability of assembled bridge piers, this study simulated the potential damage to epoxy-coated steel bars at various stages of an actual construction process by bending, scratching, and knocking. The pier inter-segmental joint and the pier-bearing platform joint were designed to highlight the critical zones affecting the durability of sea-crossing bridge substructures. The migration of chloride ions into the concrete was accelerated by applying a constant voltage DC electric field. The electrochemical indexes of epoxy-coated steel bars and chloride ion content in concrete were measured regularly. Results show that the corrosion risk and corrosion rate of steel bars increase significantly when the damaged area ratio of epoxy coating is higher than 5%. The chloride ion transport rate at the interface of the pier-bearing platform joint is about 5 times that of the pier inter-segmental joint. The service life of the pier-bearing platform joint is only 1/2 that of the pier inter-segmental joint when epoxy-coated steel bars with the same treatment are used. [ABSTRACT FROM AUTHOR]

Reactive powder concrete (RPC) is widely used in large-scale bridges, and its durability in coastal areas has become a significant concern. Straw fibers have been evidenced to improve the mechanical properties of concrete, while research on their influence on the chloride corrosion resistance of RPC is deficient. Therefore, it is essential to establish the relationships between the quantities and parameters of straw fibers and the properties of the resulting concrete. In this study, the mass loss rates (MLRs), the relative dynamic modulus of elasticity (RDME), the electrical resistance (R), the AC impedance spectrum (ACIS), and the corrosion rates of steel-bar-reinforced RPC mixed with 0%–4% straw fibers by volume of RPC were investigated. A scanning electron microscope (SEM) and X-ray diffraction (XRD) were used to analyze the corrosion of steel bars. The reinforced RPC specimens were exposed to a 3% NaCl dry-wet alternations (D-As) and 3% NaCl freeze-thaw cycles (F-Cs) environment. The results show that, after adding 1%–4% straw fibers, the setting time and slump flow of fresh RPC were reduced by up to 16.92% and 12.89%. The MLRs were −0.44%–0.43% and −0.38%–0.42%, respectively, during the D-As and F-Cs. The relationship between the RDME and the fiber volume ratio was the quadratic function, and it was improved by 9.34%–13.94% and 3.01%–5.26% after 10 D-As and 100 F-Cs, respectively. Incorporating 4% straw fibers reduced the R values of the reinforced RPC specimens by up to 22.90% and decreased the corrosion rates after 10 D-As and 100 F-Cs by 26.08% and 82.29%, respectively. The impedance value was also increased. Moreover, a dense, ultra-fine iron layer and α-FeO(OH) were observed in the rust of rebars by SEM and XRD, as the corrosion resistance of rebars was enhanced. The results indicate that straw fibers improved the corrosion resistance of RPC, which can serve as a protective material to inhibit concrete cracking and thereby prevent rebar oxidation. This study provides theoretical support for the investigation of surface phenomena in reinforced RPC with straw fibers. [ABSTRACT FROM AUTHOR]

Zinc-substituted cobalt ferrites were obtained by a green method using a black grape extract as a reductant and fuel. XRD analysis confirmed the spinel structure of the synthesized ferrites. An increase in the lattice constant is explained by increased Zn content. SEM analysis confirmed changes in surface morphology, whereas FTIR spectra demonstrated the presence of organic species in the samples, which originated from grape extract. The content of Co(II) ions in octahedral sites as a function of the ratio between Fe(III) ions in A- and B-sites was calculated from Mössbauer data. pHPZC rose from 7.85 to 8.13 with an increase in zinc content, indicating a positive charge of the adsorbent surface at natural pH. The adsorption–catalytic properties of the spinel samples were investigated in terms of Congo Red (CR) dye removal. The mechanism of CR adsorption on the ferrite surface includes electrostatic and donor–acceptor interactions with the adsorbent surface. Furthermore, the sample with x(Zn) = 0.4 exhibited the highest degradation rate constant k = 0.102 min−1 in the peroxide oxidation of CR, whereas the sample with x(Zn) = 1.0 exhibited the highest adsorption capacity. The electron transfer between ferrite samples and hydrogen peroxide was evidenced using electrochemical tests. The green-synthesized Co-Zn ferrites demonstrate a big potential as adsorbents/catalysts for water treatment.

Chemical conversion coating (CCC) is a cost-effective and industrially scalable technique to tackle the issue of corrosion of Magnesium and its alloys, crucial for reducing global greenhouse gas emissions by the road transportation sector. Amongst all the possible CCCs, the phosphate conversion coating (PCC) has one of the highest industrial application potential. This article demonstrates limitations in the traditional understanding of Mg-PCC mechanism, primarily dictated by increased local pH near the Mg-substrate leading to double deprotonation of phosphoric acid (H3PO4 → H2PO4− + H+; H2PO4− → HPO42− + H+). The HPO42− further reacts to Mg2+ and subsequent supersaturation of precipitate, MgHPO4.3H2O results in the coating formation. The new hypothesis proposed for Mg-PCC is based on the argument that the second deprotonation reaction is energetically unfavorable, instead, the reaction is mostly limited to the first deprotonation of the phosphoric acid resulting in H2PO4−. This H2PO4− reacts to the Mg2+ and forms an intermediate complex ion, (Mg2+-H2PO4−)+. The Mg substrate, when exposed to an aqueous environment, releases Mg2+, resulting in a negatively charged substrate. The complex (Mg2+-H2PO4−)+ ions are electrostatically attracted to the negatively charged substrate resulting in the reaction responsible for MHPT (MgHPO4.3H2O) coating. This new hypothesis is supported by thermodynamic calculations through density functional theory (DFT) and experiments.

To assess the corrosion resistance of Cu-Fe deformation in situ alloys in a chloride ion environment, Cu-Fe alloys with varying Fe contents (5 wt%, 10 wt%, and 14 wt%) were prepared using vacuum induction melting, and the impact of Fe content on the corrosion resistance was examined. The corrosion morphology and corrosion products were analyzed, and the corrosion rate, corrosion period, dynamic potential polarization curves, electrochemical parameters, and electrochemical impedance spectra with different Fe contents were determined. However, the corrosion resistance of Cu-Fe alloys initially increased with an increase in Fe content before decreasing, with Cu-10 wt% Fe alloys (95% reduction rate) exhibiting the best corrosion resistance. As the Fe content increased, the amount of primary Fe phase gradually increased and became more densely distributed. This led to an increase in the dense oxide film on the surface, thereby enhancing the corrosion resistance of the material. Moreover, with a further increase in Fe, the primary Fe phase exhibited coarsening and non-uniform distribution. This resulted in the oxide film becoming looser, leading to a decreased corrosion resistance of the alloy.

GH907 superalloy has been widely used in aircraft，ship and other industries.Because GH907 superalloy will be corroded when used in marine environment， it is necessary to study its corrosion behavior.In this work， the corrosion behavior of GH907 superalloy material in simulated marine environment was studied by neutral salt spray test.The 2D and 3D morphology of GH907 superalloy after corrosion were observed by means of scanning electron microscope (SEM)，X-ray energy dispersive spectroscopy (EDS) and 3D confocal laser scanning，and the composition of GH907 superalloy was analyzed.Moreover，the electrochemical corrosion behavior of GH907 superalloy was analyzed through electrochemical tests of potentiodynamic scanning and electrochemical impedance spectroscopy.Results showed that GH907 material would undergo passivation behavior during neutral salt spray corrosion.After corrosion， the corrosion current density of GH907 increased， the corrosion resistance decreased， and the corrosion products and passivation film possessed limited ability to protect the material.Furthermore， the main corrosion type was pitting corrosion.EDS results revealed that the corrosion products in the pitting pits were mainly Fe oxides， with very low Ni and Co element contents.Besides， the charge transfer and diffusion behavior existed in the corrosion process， and the corrosion system was an activation control system.

In this research, corrosion behavior and discharge capabilities of the AZ61-In alloy experiencing hot rolling process have been discussed in detail. The results reveal that the introduction of indium to magnesium facilitates the dissolution of magnesium by augmenting a quantity of secondary phases, generating less-protective products. The corrosion resistance of AZI plus 50 % rolling reduction is improved attributed to the preferred basal orientation and further recrystallization. Moreover, the average discharge potentials of AZI-50 % can respectively reach −1.551 V and −1.234 V at 10 mA cm−2 and 50 mA cm−2, showing potential for application in seawater activated batteries.

In order to adapt to the rapid development of green plant extract corrosion inhibitors, spinach extract (SPE) was selected as a corrosion inhibitor for Q235 steel in citric acid (CA) environment. SPE was extracted using a simple ethanol reflux method, and its main components, as well as their stability in CA, were confirmed through Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible spectroscopy (UV-Vis). The corrosion inhibition performance of SPE on Q235 steel in 0.5 mol/L CA solution was investigated using various methods including weight loss, dynamic potential polarization (PDP), linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and contact angle measurements. Effects of temperature on the activation parameters (Ea, were studied by calculation. Results showed that chlorophyll was the main component of SPE, which exhibited good stability in a 0.5 mol/L CA solution. Furthermore, SPE significantly reduced the corrosion rate of Q235 steel in the 0.5 mol/L CA medium, acting as a mixed corrosion inhibitor for both cathodic and anodic reactions. With the increase of SPE concentration, both cathodic and anodic currents were reduced, active corrosion sites were blocked, the corrosion rate was decreased, and the corrosion inhibition efficiency was enhanced. The corrosion inhibition efficiency of Q235 steel obtained by weight loss method, PDP, LPR and EIS was more than 80% with 2.134 g/L of SPE concentration at 303 K. With the increase of system temperature, the corrosion inhibition efficiency of SPE on Q235 steel decreased, but the change was smaller. Compared to the blank system, the activation energy (Ea) of the system significantly increased after the addition of SPE. The effective components of SPE adsorped to the surface of Q235 steel in accordance with the Langmuir isotherm, predominantly through physical adsorption, and were characterized as monolayer adsorption. SPE exhibited good corrosion inhibition performance for Q235 steel in a 0.5 mol/L CA solution system, which was a green corrosion inhibitor with good application prospects in the pickling field. It could provide certain guidance for the development of plant extract-based corrosion inhibitors.

Mooring chains are key components of offshore floating photovoltaic systems. Although their service safety is often affected by the harsh service environment, the influence of surface roughness on their corrosion resistance is not clear. This study investigated the corrosion behavior of mooring chain steel using cyclic salt-spray corrosion and electrochemical tests. Scanning electron microscopy, energy-dispersive spectrometry, optical profilometry, and other analytical techniques were used to study the composition and morphology of the corrosion products. The corrosion behavior was studied by electrochemical polarization curves, alternating current impedance spectroscopy, and X-ray photoelectron spectroscopy. The results show that the salt-spray corrosion resistance of mooring chain steel significantly improved with the reduction in specimen surface roughness, and the number and depth of corrosion pits were reduced. Mass loss after 24 h of salt-spray corrosion was exponentially related to initial roughness (Ra). Improved surface roughness significantly increased the pitting potential of the specimens, widened the passivation range, and enhanced the repassivation capability, thus significantly improving the pitting resistance. The pitting potential is linearly related to the initial roughness of the specimen. The oxide contents of Fe, Mo, and Si in the passivation film tended to increase with a smoother surface, which contributes to its densification. This effectively blocks chloride ion attack, thus improving the corrosion resistance of the mooring chain steel.

Enhancing corrosion resistance of Mg-Zn alloys with high strength and low cost was critical for broadening their large-scale practical applications. Here we prepared solutionized, peak- and over-aged ZK60 alloys with and without microalloying Ca (0.26 wt.%) to explore the effects of nanoscale precipitates on their corrosion behavior in detail via experimental analyses and theoretical calculations. The results suggested the peak-aged ZK60 alloy with Ca addition showed improved corrosion resistance in comparison with the alloys without Ca, owing to the contribution of Ca on the refinement of precipitates and increase in their number density. Although the precipitates and Mg matrix formed micro-galvanic couples leading to dissolution, the fine and dense precipitates could generate “in-situ pinning” effect on the corrosion products, forming a spider-web-like structure and improving the corrosion inhibition ability accordingly. The pinning effect was closely related to the size and number density of precipitates. This study provided important insight into the design and development of advanced corrosion resistant Mg alloys.

In order to solve the problem of atmospheric corrosion of wheel steels during their service，the initial corrosion behaviors of two kinds of automotive wheel steels 590CL and 780CL at 590 MPa and 780 MPa levels in neutral salt spray environment of 5% NaCl solution were studied by neutral salt spray test.The morphology， structure， corrosion rate and electrochemical behavior of corrosion products after salt spray test were characterized by glow spectrometer， metallographic microscope， scanning electron microscope (SEM)， X-ray diffractometer (XRD)and electrochemical measurement.Results showed that after 48 h in the neutral salt spray test， red rust appeared on the surface of the two wheel steels， and the corrosion rates of the two were 590CL＞780CL.The polarization curves and electrochemical impedance spectroscopy results measured in 3.5%NaCl solution were in good agreement with the above results.Besides， the corrosion products of 590CL and 780CL steels were mainly γ-FeO(OH)， and also contained some α-FeO(OH) and Fe3O4.However， the corrosion products basically had no protective effect on the substrate.

In this study, a novel type of green and highly efficient Na-CDs corrosion inhibitor was successfully prepared using a hydrothermal method, and its properties were thoroughly characterized. The results revealed that the Na-CDs possessed a uniform nanoscale size distribution and a well-defined graphene lattice structure. The corrosion inhibition performance of Na-CDs at varying concentrations was assessed, and it was found that the corrosion inhibition efficiency initially increased with the increase of concentration, peaking at over 96 % when the concentration reached 150 mg/L, before subsequently declining. Analysis of the adsorption behavior of Na-CDs on the metal surface confirmed that the adsorption process followed the R-P adsorption isotherm, indicative of an almost ideal homogeneous monolayer adsorption. The corrosion inhibition mechanism is the result of forming a protective film on the metal surface by physical adsorption and chemical adsorption, with the bridging role of Cl- further reinforcing the structure of this film. However, at excessively high concentrations of Na-CDs, desorption occurred, compromising the integrity of the protective film. This study enriches the field of metal-doped carbon dots as corrosion inhibitors and provides insights into the synthesis of carbon dots and the development of carbon dot-based corrosion inhibitors.

The overall corrosion behavior of S304 stainless steel and A3 carbon steel in 30 wt.% MEA (monoethanolamine) and AMP/MEA (2‐amino‐2‐methyl‐1‐propanol / monoethanolamine) blended amine solutions at 40–100°C was investigated. The characterization analysis of the corroded material surfaces was performed, and the changes in the properties of both solvents after long‐term immersion corrosion were measured, including the accumulation of heat stable salts (HSS) and viscosity changes. The results of the long‐term immersion corrosion experiments showed that the corrosion rate of S304 stainless steel was significantly lower than that of A3 carbon steel in both amine solutions. However, the corrosion rate of both materials exhibited a similar trend, initially decreasing and then stabilizing over time. Due to the higher concentration of carbonate ions in the AMP/MEA system, it exhibited better overall corrosion resistance and degradation resistance compared to the MEA system. The main component of the corrosion product on carbon steel was identified as Fe2(OH)2CO3. The electrochemical test results showed that the corrosion current of S304 stainless steel was much smaller than that of A3 carbon steel, and its charge transfer resistance was much higher, indicating that it was less prone to electron loss in the organic amine solutions. Additionally, the AMP/MEA system exhibited superior corrosion resistance. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Magnesium ammonium phosphate cement (MAPC) with a ceramic-like structure has good anti-corrosion properties. As an anti-corrosion coating, it can resist steel corrosion and reduces economic losses caused by steel corrosion. To further improve the anticorrosive properties of the coating, this study modified MAPC by partially replacing MgO with metakaolin (MK). Electrochemical tests analyzed the effect of MK on the anticorrosive properties of the coating. The results showed that the incorporation of MK significantly improved the anticorrosive properties of the coating, and the maximum improvement was obtained when the substitution amount was 15%. The compositions and microscopic morphology of the coatings were analyzed by X-ray diffraction (XRD), thermogravimetric analysis (TG-DTG), and scanning electron microscopy (SEM). According to the results, MK addition did not significantly alter the main composition of the coating, but the MK promoted the formation of MgNH4PO4·6H2O(MAP) to some extent. The microscopic morphology of the coating surface showed that the crystals were stacked together in flower-like layers before soaking, and the crystals grew more entirely after soaking. The internal microstructure of the coating is very dense, which helps to resist the erosion of corrosive media. In addition, the changes in coating pores before and after the incorporation of MK were tested by low-field nuclear magnetic resonance (LF-NMR). Based on the results, the doping of MK can optimize the pores of the coating and reduce its porosity. It is feasible to replace part of the MgO with MK to improve the corrosion resistance of magnesium phosphate cement-based coating, and the optimal dosage of MK is 15%. This research is helpful to improve the anti-corrosion performance of the coating and reduce corrosion costs. [ABSTRACT FROM AUTHOR]

To reveal the influence of joint type and epoxy-coated steel bar surface damage on the durability of assembled bridge piers, this study simulated the potential damage to epoxy-coated steel bars at various stages of an actual construction process by bending, scratching, and knocking. The pier inter-segmental joint and the pier-bearing platform joint were designed to highlight the critical zones affecting the durability of sea-crossing bridge substructures. The migration of chloride ions into the concrete was accelerated by applying a constant voltage DC electric field. The electrochemical indexes of epoxy-coated steel bars and chloride ion content in concrete were measured regularly. Results show that the corrosion risk and corrosion rate of steel bars increase significantly when the damaged area ratio of epoxy coating is higher than 5%. The chloride ion transport rate at the interface of the pier-bearing platform joint is about 5 times that of the pier inter-segmental joint. The service life of the pier-bearing platform joint is only 1/2 that of the pier inter-segmental joint when epoxy-coated steel bars with the same treatment are used.

Corrosion inhibitors play a vital role in impeding the corrosion process of steel bars within concrete structures exposed to corrosive environments. Nevertheless, conventional corrosion inhibitors pose environmental risks. In contrast, contemporary studies have explored corrosion inhibitors that are eco-friendly. However, these inhibitors are burdened by high costs and complex production processes, impeding the widespread application in concrete structures. Consequently, this study presents an innovative solution by incorporating uniconazole, an agricultural fungicide, as a corrosion inhibitor for steel bars in concrete structures. The steel bars were exposed to corrosion within a simulated concrete pore solution containing 0.6 mol/L NaCl, both with and without the presence of uniconazole. The morphology and hydrophilicity of the steel bar surface were investigated via optical microscope and contact angle experiments. Electrochemical tests (open circuit potential, potentiodynamic polarization, electrochemical impedance spectroscopy, and Mott-Schottky analysis) and X-ray photoelectron spectroscopy were employed to investigate the corrosion inhibition performance and mechanism of uniconazole. The results demonstrate that uniconazole elevates the hydrophobicity and contributes to the corrosion inhibition of steel bars. Electrochemical test results indicate that as the concentration of uniconazole increases from 1 × 10−4 mol/L to 1 × 10−3 mol/L, the inhibition efficiency likewise demonstrates a corresponding increase, escalating from around 50 %–90 %. Uniconazole molecules function as mixed-type inhibitors, exhibiting characteristics of both anode-type and cathode-type inhibitors. The adsorption of uniconazole enhances the stability and thickness of the passive-adsorbed layer on the steel surface, effectively impeding the charge transfer process and obstructing the interaction of corrosive substances with the base metal. In summary, the application of uniconazole exhibits the highlights of efficient, cost-effective, environmentally friendly, and the potential for scalable production. This positions uniconazole as a promising candidate for use as a corrosion inhibitor in the domain of concrete structures.

Using the environmentally friendly biomaterial 4-amino-6-hydroxy-2-mercaptopyrimidine (AMSN) and the anhydrous N,N-dimethylformamide (DMF), a high performance pyrimidine derivative ASMF, which is a corrosion inhibitor for acid job, has been developed through one-step reaction. Characterization by IR spectroscopy and element analysis show that the reaction gave high purity product. Studies on the factors affecting the yield of ASMF show that the optimum molar ratio of AMSN and DMF is 1:1, the reaction temperature should not be higher than 170 °C, and the reaction time should be at least 4 h. The yield of ASMF is relatively high under these conditions. An ASMF sample produced in an experimental production showed excellent corrosion inhibitive capacity in high concentration (>20%) acid solutions, and it functioned at temperatures as high as 170 °C. ASMF shows superior corrosion inhibitive performance even at concentrations less than 0.2%. The electrochemical polarization curve of ASMF shows that ASMF can effectively inhibit the electrode reactions taken place at the cathode and anode during a corrosion process, and it is a mixed corrosion inhibitor which shows cathode inhibition property. Impedance test results show that ASMF has good corrosion inhibition efficiency, at a concentration of 0.2%, the corrosion inhibition efficiency of ASMF is 99.85%. Core damage evaluation test results show that ASMF shows only weak damage to the permeability of cores flooded with the ASMF solution, and ASMF is environmentally friendly. It can be concluded that the product developed is an environmentally friendly high performance pyrimidine derivative corrosion inhibitor for acid jobs. [ABSTRACT FROM AUTHOR]

Coating a sword with a layer of clay prior to water quenching is one way to promote hardening and improve corrosion resistance. In this study, two types of clay coating were prepared on two identical steel swords (L04 and L05) in order to explore the effects of the addition of clay on the microstructure of steel. Samples taken from each blade were compared using metallography, XRD tests, microhardness tests, and electrochemical tests, and the results showed that L04 had a wavy pattern and contained pearlite, martensite, and residual austenite, while L05 had a mesh pattern and consisted of acicular and lath martensite. More importantly, the electrochemical tests indicated that L05 exhibited better corrosion resistance than L04. Each test zone of L05 (with icorr values of 2.48~8.08 μA·cm−2) had lower corrosion rates compared to the corresponding zones of L04 (with icorr values of 2.93~10.44 μA·cm−2). Furthermore, the calculated Rp values of each test zone of L05 (2341~8260 Ω·cm2) were higher than the values of the corresponding zone of L04 (1908~6716 Ω·cm2). These results further demonstrate that the second method of clay coating endowed superior anti-corrosion performance. In addition, the overall strength and toughness of L04 were achieved with a lower hardness back (mean value 320 HV) and a higher hardness edge (mean value 850 HV), whereas the overall strength and toughness of L05 were achieved with a high hardness throughout (mean value 640 HV of the back and 725 HV of the edge). [ABSTRACT FROM AUTHOR]

In this research, peanut shell and urea were used as raw materials to successfully prepare N-doping biochar with a good ability to activate perdisulfate (PDS) to degrade phenol. The effects of carbonization time, co-pyrolysis temperature, co-pyrolysis time, and the doping ratio of biochar on the activation of persulfate were studied. The results showed that the efficiency of phenol degradation catalyzed by persulfate and biochar was 93%, and the total organic carbon (TOC) removal rate reached 66%. Besides, the phenol removal rate could also maintain 81% after four cycles. Moreover, the free radicals and non-free radicals was confirmed by Electron paramagnetic resonance (ESR) and capture experiments. The results of Density Functional Theory (DFT) calculations showed that the electron distribution of N-doping biochar became more uneven compared with the original biochar. This study provides a reference for the treatment of phenolic wastewater and may promote the understanding of N-doping biochar/persulfate degradation mechanism. [ABSTRACT FROM AUTHOR]

Context: In this work, the corrosion inhibitive effect of acetoxime derivative of zinc chloride, (ZnCl2.2HON=C(CH3)2) (ZA), was investigated on mild steel in epoxy/polyamide coating. ZA was used to modify diglycidyl ether of bisphenol A (DGEBA) to yield novel anticorrosive coating (epoxy-ZA) with excellent barrier characteristic. The dispersal of ZA may lead to the formation of Zn–O–C and O–Zn–O linkages in the polymer framework which act as inorganic fillers producing a dense structure of hybrid coating. In electrochemical findings, electrochemical impedance spectroscopy (EIS) and Tafel polarization (TP) indicate higher protection efficiency for epoxy-ZA coatings (99.99 and 99.93 % for EIS and TP, respectively) as compared to others. Using surface analysis and electrochemical data, it was concluded that an inhibition synergy was developed when ZA was taken instead of acetoxime or zinc chloride (ZC) alone in the coating formulation. Methods: Fourier transform infrared (FT-IR) was used to investigate epoxy interaction with zinc compounds and scanning electron microscopy (SEM) was used to investigate morphology of the samples. To reinforce the experimental results, reactivity of crosslinked epoxy and epoxy-ZA coatings with metallic surface was also explored using density functional theory (DFT) with basis set B3LYP/6-311G(d,p) and molecular dynamics (MD) methods by using Forcite module. Modification of epoxy with ZA enhances its interaction with steel surface in dry as well as in wet conditions as indicated by the adhesion energy calculated by MD simulations. [ABSTRACT FROM AUTHOR]

• Microalloying Ca (0.26 wt.%) combined with appropriate heat treatments can significantly improve corrosion and mechanical properties of the commercial ZK60 magnesium alloy. • The peak-aged ZK60-Ca alloy exhibits the highest hardness and yield strength, and lowest corrosion rate among the aged alloys. • The corrosion resistance improvement of the aged ZK60-Ca alloy is attributed to the "in-situ pinning" effect of precipitates on the corrosion products. • The pinning effect is associated with the size and number density of precipitates, which is verified via experimental results and theoretical calculation. Enhancing corrosion resistance of Mg-Zn alloys with high strength and low cost was critical for broadening their large-scale practical applications. Here we prepared solutionized, peak- and over-aged ZK60 alloys with and without microalloying Ca (0.26 wt.%) to explore the effects of nanoscale precipitates on their corrosion behavior in detail via experimental analyses and theoretical calculations. The results suggested the peak-aged ZK60 alloy with Ca addition showed improved corrosion resistance in comparison with the alloys without Ca, owing to the contribution of Ca on the refinement of precipitates and increase in their number density. Although the precipitates and Mg matrix formed micro-galvanic couples leading to dissolution, the fine and dense precipitates could generate " in-situ pinning" effect on the corrosion products, forming a spider-web-like structure and improving the corrosion inhibition ability accordingly. The pinning effect was closely related to the size and number density of precipitates. This study provided important insight into the design and development of advanced corrosion resistant Mg alloys. [ABSTRACT FROM AUTHOR]

In the present study, carbide-free nanostructured bainite is produced by austempering high carbon and silicon steels at 250 °C. Fine pearlitic structure is also made by patenting the steels of selected compositions at 550 °C. The formation of carbide-free nanostructured bainite and retained austenite in the austempered steels and ferrite and cementite in patented steels were confirmed through X-ray diffraction and TEM studies. The optical, scanning and transmission electron microscopies reveal the presence of nanoscale bainite, filmy and blocky austenite in austempered steels and the presence of lamellar pearlite in patented steels. Increasing austempering time enhances the amount of bainite but decreases the blocky retained austenite. The corrosion behaviour of the newly developed bainitic steels is compared with that of pearlitic steel of the same compositions. Electrochemical and immersion corrosion tests are conducted in an aqueous 3.5% NaCl solution. The corroded surfaces are analyzed with the scanning electron microscope (SEM) and X-ray photoelectron spectrometer (XPS). Corrosion resistance increases with increasing carbon percentage due to the formation of magnetite (Fe3O4), provided the content of other alloying elements remains the same. The presence of Ni decreases corrosion rate significantly, i.e., enhances corrosion resistance, charge transfer resistance (Rct) and polarization resistance (Rp). Reducing retained austenite in nanostructured steel decreases the corrosion rate due to the lesser area of Galvanic couples and the formation of uniform, compact, and non-porous passive layer. The bainitic steel samples demonstrated superior corrosion resistance to that of the pearlitic steel due to lesser cell formation. The corrosion mechanisms of high-carbon bainitic and pearlitic steel are discussed. [ABSTRACT FROM AUTHOR]

In this research, influence of boron carbide (B4C) particles on the corrosion behavior of magnesium metal matrix composite is examined. AZ31-B4C composites are fabricated through ultrasonic vibration-assisted stir casting process by reinforcing varying amount of boron carbide (0.5–2 wt.%) in AZ31 alloy. Characterizations of the composites are carried out using optical microscope , scanning electron microscope (SEM) and energy-dispersive spectroscope (EDS). The optical images show equiaxed orientation of grains in fabricated composites. SEM analysis confirms uniform distribution of reinforcement particles in composites. EDAX result confirms the inclusion of B4C particles in the Mg matrix. The microhardness of all composites and base alloy is measured using Vickers's microhardness tester. Microhardness values are found to be increased with increase in wt.% of B4C nanoparticles. Electrochemical corrosion tests are carried out on AZ31-B4C metal matrix composites in 3.5% NaCl solution. AZ31-1B4C composite is found to be the most corrosion-resistant material among tested materials. Furthermore, corrosion morphology of samples is scrutinized under SEM and EDS. [ABSTRACT FROM AUTHOR]

New-type magnesium alloy with prominent solubility and mechanical property lays foundation for preparing fracturing part in petroleum extraction. Herein, Mg-xZn-Zr-SiC alloy is prepared with casting strategy. Electrochemical and compression tests are conducted to assess the feasibility as decomposable material. Morphology, composition, phase and distribution are characterized to investigate decomposition mechanism. Results indicate that floccule, substrate component and reticulate secondary phase are formed on as-prepared surface. Sample also acts out enhanced compression strength to maintain pressure and guarantee stability in dissolution process. Furthermore, as decomposition time and zinc content increase, couple corrosion intensifies, resulting in gradually enhanced decomposition rate. Rapid sample decomposition is mainly due to basal anode dissolution, micro particle exfoliation and poor decomposition resistance of corroding product. Such work shows profound significance in preparing new-type accessible alloy to ensure rapid dissolution of fracturing part and guarantee stable compression strength in oil-gas reservoir exploitation.

MoO3/WO3 composite films with different MoO3 deposition cycles were prepared to use conductive glass as the substrate by combining hydrothermal method and electrochemical deposition method. Electrochromic reversibility, optical density(ΔOD), coloration efficiency, stability and responding time of MoO3/WO3 composite film were obtained by electrochomical measurement technologies and spectral tests. The results show that the MoO3/WO3 composite film with 8 MoO3 electrodeposited cycles has the best electrochromic performance compared with single WO3 nanorod film or MoO3 film, and the electrochromic reversibility is 62.19%, the optical density is 0.61, the coloration efficiency is 153.16 cm2/C, the coloring and bleaching responding time is 8.37 s and 4.77 s, respectively. It the meanwhile, it has a narrower band gap and higher cyclic stability.

Abstract In this study, new polypyrrole films (ppy) were synthesized using a physical plasma deposition (PAPVD) system; where the equipment design and methodology for plasma-assisted pyrrole polymerization were improvement. The morphology, functional groups, and thermal stability of the polymer network films were characterized by X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) techniques, respectively. The electrochemical properties of the films as capacitor were evaluated by cyclic voltammetry and electrochemical impedance spectroscopy. The results observed by SEM showed that the ppy 100W-1 and ppy 100W-2 films present uniformity in their structure. The analyses of TGA and DSC confirmed the improvement in stability; meanwhile for 100W-1 film, the presence of ppy bonds was corroborated by XPS. Plasma-activated ppy 100W-1 film exhibited higher capacitance and minor Rct resistance than that obtained for ppy 100W-2 film. The specific capacitances values of ppy 100W-1 and ppy 100w-2 films are 196 and 150 F/g in 1 M KCl. After charging and discharging tests of 1000 cycles at 5 mA cm−2 current density of ppy 100W-1 film retains 89% of its initial capacitance. Therefore, ppy 100W-1 film showed to be a promising material for use as an electrochemical capacitor.

In order to study the corrosion dynamics of low carbon steel in neutral salt spray environment, the low carbon steel samples were carried out neutral salt spray corrosion test (SST). The corrosive behavior of low carbon steel was examined by scan electron microscopy, electrochemical impedance spectra, and potentiodynamic polarization, and the salt spray corrosion dynamics laws of low carbon steel were discussed. SST results showed that as the corrosion progresses, the rust layers will become dense, forming a "scab" structure, and forming an occluded corrosion zone with the substrate, resulting in increased corrosion rate. The newly generated inner rust layers were loose and expanded outward, caused the "scab" structure to peel off, and this has a certain periodicity. After corrosion, the surface of the substrate is pit-shaped, which uniformity is poor. Electrochemical tests showed that the corrosion process of low carbon steel in salt spray environment was mainly controlled by cathode diffusion, and the corrosion rate was relatively stable. [ABSTRACT FROM AUTHOR]

The modified 27CrMo steel is turned into the 120 and 125 ksi drill pipes via the heat treatment process. The corrosion properties of the said two drill pipes are compared and analyzed by means of the electrochemical technology test tests, the immersion test and the sulfide stress corrosion test. The results show that the 120 ksi drill pipe develops oval corrosion pits, while the 125 ksi drill pipe develops thin an long corrosion pits the depth of which is two times that of the former, and at the bottom of which corrosive fractures are found. The 120 ksi drill pipe has passed the SSC test as per NACE TM 0177, Method A, Solution D, whereas the 125 ksi drill pipe has fractures in mode of intergranular fracture, which means that its anti-SSC property is poor. [ABSTRACT FROM AUTHOR]

In order to improve the surface quality of tantalum wafer after chemical mechanical polishing (CMP), the effects of the particle size of nano-silica sol, type and mass fraction of chelating agent (i.e. glycine and disodium ethylenediaminetetraacetate), and mass fraction of oxidant (hydrogen peroxide) on the electrochemical behavior and removal rate of tantalum wafer, and its surface quality after polishing were studied by electrochemical testing and CMP experiments. The results showed that the removal rate of tantalum wafer was 71 nm/min when being polished in a slurry comprising 40% of nanosilica sol with an average particle size of 50 nm as abrasive, 1.0% of disodium ethylenediaminetetraacetate as chelating agent, and 1.0% of hydrogen peroxide as oxidant. The surface of polished tantalum wafer was free of orange peel and scratch. [ABSTRACT FROM AUTHOR]