Electrochemical Corrosion Behavior Research Articles

The electrochemical corrosion behavior and antibacterial properties of Cu-xFe alloy

Copper-based alloys have garnered significant attention for their potential in antimicrobial applications aimed at mitigating medical-related infections. Nonetheless, the alloying elements in conventional copper alloys frequently exhibit biotoxicity. This study explored the corrosion behavior, antimicrobial activity, and ion release of Cu–Fe alloys with varying iron contents and aging treatment. The results indicate that increasing the iron content in Cu–Fe alloys and applying appropriate aging treatment can enhance both the antibacterial efficiency and corrosion rate. Transmission electron microscopy (TEM) observations revealed a corrosion mechanism in which dispersed iron phases act as nucleation sites. These nanoscale precipitates increase the Cu/Fe interfacial area, thereby promoting ion release at the interface. Furthermore, in-situ scanning electron microscopy (SEM) revealed that corrosion products are more likely to detach in iron-rich segregated areas, which effectively promotes the sustained release of copper ions.

Influence of Ni content on electrochemical corrosion and tribological behavior of Cu-10Sn coatings by laser cladding

In this work, Cu-10Sn-xNi (x = 0, 3, 6, 9, and 12 wt%) alloy coatings were prepared using laser cladding technology. The influence of Ni content on the phase composition, microstructure, crystallographic characteristics, microhardness, electrochemical corrosion, dry sliding wear and corrosive wear behavior of the coatings were studied. The results indicated that the coatings formed good metallurgical bond with the substrate. The coatings were composed primarily of the α-Cu matrix and small γ precipitates. The Ni element effectively reduced component segregation, and with the increased of Ni content, the grain size in the coating was significantly refined, resulting in fine equiaxed grains. Under the effect of fine grain strengthening, the Cu-10Sn-12Ni (C12NS) coating achieved a higher microhardness of approximately 222.9 ± 5.3 HV0.2. In the electrochemical corrosion test, the increased in the number of grain boundaries significantly reduced the corrosion resistance of the Cu-10Sn-xNi coatings. The Cu-10Sn-6Ni (C6NS) coating exhibited excellent corrosion resistance, with an Icorr of only 1.37 μA/cm2. The results of the dry sliding wear test showed that under the influence of the hardness gradient between the hard precipitate phase and the soft matrix of the coating, the C6NS coating achieved satisfactory wear resistance with a specific wear rate of 3.30 × 104 μm3/Nm. Meanwhile, due to the good corrosive resistance, the C6NS coating showed the best tribological performance in 3.5 wt% NaCl environment, and the specific wear rate was 1.58 × 104 μm3/Nm.

The Study of the Electrochemical Corrosion Behavior of Cu-30%Fe Nanoalloy

In this work, we have developed Cu-Fe alloys with a nanometric structure through the process of mechanosynthesis. We then followed the formation mechanism of these alloys and proceeded with a crucial step, which is cold compaction. We have elaborated Cu-Fe alloys with a nanometric structure by mechanosynthesis and following the mechanism of formation of these alloys, the we employed various analytical techniques to characterize the structural and microstructural properties of our powders. The X-ray diffraction method (XRD) was used to calculate the structural parameters, while laser granulometry was employed to study the evolution of particle size. Scanning electron microscopy (SEM) was then utilized to examine the morphology of the powders. Additionally, we investigated the electrochemical behavior of our alloys, focusing on their corrosion resistance. Electrochemical impedance spectroscopy (EIS) was performed in the frequency range of 10 kHz to 15 mHz to evaluate the corrosion performance.

Electrochemical Corrosion Behavior and the Related Mechanism of Ti3SiC2/Cu Composites in a Strong Acid Environment.

The electrochemical corrosion behaviors of Ti3SiC2/Cu composites in harsh media including dilute HNO3 and concentrated H2SO4 were studied in detail and the related corrosion mechanisms were explored. Under open-circuit potential, the corrosion resistance of Ti3SiC2/Cu in dilute HNO3 was worse than that in concentrated H2SO4. In dilute HNO3, Ti3SiC2/Cu exhibited a typical passivation character with a narrow passivation interval. During the corrosion process, the dissolution of Cu-Si compounds resulted in the destruction of the passivation layer on the surface. Additionally, with the increasing of the potentials, the oxidation of Cu and Si atoms led to the generation of the oxide film again on the surface. In concentrated H2SO4, the Ti3SiC2/Cu composite was covered by a double-layered passivation layer, which was composed of an internal layer of TiO2 and an external layer of Cu2O and SiO2. This was because Cu diffused into the surface and was oxidized into Cu2O, which formed a denser oxidized film with SiO2. In addition, it was found that Ti3SiC2/Cu has better corrosion resistance in concentrated H2SO4.

Study on corrosion resistance of arc sprayed Zn–xAl (x = 19, 27, and 37) pseudo alloy coatings in salt spray environment

AbstractTo study the corrosion behavior of Zn–Al pseudo alloy coatings with different Al contents, Zn–xAl (x = 19, 27, and 37) pseudo alloy coatings were prepared by the wire arc spraying technique using Zn and Al wires with different diameters. This study investigated the microstructure, electrochemical corrosion behavior, and corrosion morphology and products of the as‐sprayed coatings after the salt spray test in 5 wt% NaCl solution. The results exhibited that the Zn–Al pseudo alloy coatings with higher Al content form denser corrosion products (Zn5(OH)8Cl2·H2O and Zn–Al layered double hydroxide) with stronger self‐shielding effect against corrosive media, thus provide better long‐term corrosion protection. Besides, electrochemical reactions are controlled by mass transfer until corrosion for 24 h, and then by a combination of mass transfer and diffusion for 96 h. Overall, it can be concluded that the Zn–37Al pseudo alloy coating in this study shows great potential to protect steel substrates from corrosion.

Investigation of supercritical CO2 corrosion behavior of X80 carbon steel in pipelines: An in situ experimental and DFT study

The electrochemical corrosion behavior of X80 carbon steel was investigated in a supercritical CO2 (sCO2) environment at 60 ℃ and 9 MPa, by in-situ experiments and density functional theory (DFT) calculations, revealing the corrosion mechanism. For in situ electrochemical measurements, two novel CO2-rich and H2O-rich cells were developed to replace the traditional three-electrode cell. Electrochemical impedance spectroscopy revealed distinct differences in the corrosion behavior between CO2-rich and H2O-rich environments during the later stages of testing. In H2O-rich environments, as corrosion time increased, the corrosion product layer gradually changed from porous to dense, eventually forming a protective layer. In CO2-rich environments, corrosion occurs mainly in areas where water condenses to form FeCO3. Simultaneously, microscopic calculations provided evidence for the three-step sCO2 hydrolysis mechanism and the formation of FeCO3 products.

In-situ electrochemical corrosion behavior of oil well tubing in CO2-containing highly mineralized oilfield produced water: Revealing the effect of temperature

In-situ electrochemical corrosion behavior of oil well tubing in CO2-containing highly mineralized oilfield produced water: Revealing the effect of temperature

Microstructure and corrosion behaviour of metal copper parts formed by laser shock

The effects of laser shock forming (LSF) on material microstructure evolution and its electrochemical corrosion behaviour were investigated. Results show that high-density dislocations and stacking faults are formed on the laser-irradiated surface layer of parts. The laser-irradiated surface of the parts subjected to two-shot LSF exhibited better corrosion resistance, with a 2-fold decrease in the passive current density, 3.5-fold increase in the charge resistance, and ∼12-fold thicker passive film compared with the undeformed sheet. The formation of nano-grains, compressive residual stresses, and a dense Cu2O oxidation film during LSF contributed to the improved corrosion resistance of the LSF-fabricated copper parts.

Machine learning-assisted prediction and interpretation of electrochemical corrosion behavior in high-entropy alloys

In this study, machine learning (ML) models were successfully employed to predict the short-term electrochemical corrosion behavior of high-entropy alloys (HEAs) based on their chemical compositions. Considering the vast compositional space of HEAs, which restricts the development of corrosion-resistant HEAs, and the lack of non-destructive methods to qualitatively assess their corrosion resistance, this work represents a significant advancement in the field. The “three-step” method was applied to select the optimal feature set from 38 features, and six ML regression models were trained and compared. The eXtreme Gradient Boosting (XGBoost) and Gradient Boosting Decision Tree (GBDT) algorithms demonstrated the highest predictive accuracy (R2 = 81.02 % and 84.64 %, respectively) among the six algorithms. The model’s robust generalization capabilities were confirmed through validation on an additional dataset. Moreover, the interpretability of the model was enhanced by employing two analysis methods, which revealed that pH as an environmental factor, electronegativity difference and average electronegativity as empirical parameters, and the concentrations of Cr and Cu as compositional parameters have the most significant impact on the corrosion resistance of HEAs. The proposed methodology and framework have the potential to optimize alloy composition, facilitating the design and development of new corrosion-resistant HEAs.

Corrosion properties of submerged friction stir modified as-cast nickel-aluminum bronze (NAB) compositions

This study aimed to analyze the effects of adding alloying elements and cooling medium during friction stirring on the electrochemical and immersion corrosion properties. The results showed that the addition of nickel and iron prevented the formation of an unfavorable phase γ2 and instead produced intermetallic compounds κ in the microstructure. Friction stir processing (FSP) helped refine and homogenize the coarse and inhomogeneous structure of the casting, and also eliminated casting defects, whether performed in air or underwater conditions. The polarization and electrochemical impedance tests revealed that, in most cases, FSP led to a decrease in electrochemical and short-term corrosion behaviors as compared to the as-cast specimens, under the impact of alloy composition and active cooling. However, the weight loss immersion tests indicated that the friction stir processed alloys, particularly those processed underwater, demonstrated the best long-term corrosion properties. It was observed that the corrosion product film created on all models after immersion had a similar composition.

Electrochemical corrosion and product formation mechanism of M42 high-speed steel in NaH2PO4-Na2SO4 passivating electrolyte

High-speed steel (HSS) rolls operate in harsh conditions, making them vulnerable to surface degradation. Material removal technology for repairing defective HSS roll surfaces is the most effective way to maintain their integrity and reduce production costs. Electrochemical corrosion machining, with its excellent machining capabilities, offers a promising method for repairing HSS roll surfaces. However, the outer working layer of these rolls is made of premium HSS containing passivating metallic elements, complicating its corrosion behavior, particularly in passivating electrolytes. To elucidate the corrosion behavior and uncover the underlying mechanisms of corrosion and product formation of HSS during electrochemical corrosion machining, this study investigates the electrochemical corrosion process and behavior of M42 HSS used in rolls within a NaH2PO4-Na2SO4 passivating electrolyte. Metallographic etching experiments indicated that M42 HSS comprises a tempered martensitic matrix along with M2C and M6C eutectic carbides. Characteristics of oxidative reactions for M42 HSS in the electrolyte were observed in cyclic voltammetry. By conducting anodic polarization tests, along with thermodynamic analysis and characterization techniques, the entire electrode system was thoroughly examined, including corrosion phenomena, varying processes, and underlying mechanisms of corrosion and product formation. Notably, this study is the first to construct a Pourbaix diagram for the M42 HSS-H2PO4−-SO42−–H2O system. The thermodynamic analysis revealed that the applied potential variation significantly influences corrosion behavior of M42 HSS, confirming by the characterization results. The adsorption phenomenon on the cathodic surface requires a higher potential (such as 6 V) to occur. Electrochemical reactions primarily occur on the anodic surface, while the cathodic surface (or in the electrolyte) mainly engages in chemical reactions with no electronic participation. Furthermore, the electrochemical corrosion process of HSS is driven by one or more corrosion mechanisms, such as galvanic corrosion, pitting, or intergranular corrosion. Therefore, these findings from this study contribute to the development of repairing HSS roll surfaces based on electrochemical corrosion machining in future engineering applications.

Study on microstructure and electrochemical corrosion behavior of ζ-FeZn13 phase layer in hot-dip galvanized coating

In this study, the electrochemical corrosion behavior of outburst and flat ζ-FeZn13 phase layers was investigated using scanning electron microscopy, field emission scanning electron microscopy, electrochemical workstation, and Raman spectroscopy instrument. The ζ phase layer is composed of the η phase, coarse ζ phase, and fine ζ phase. Their corrosion potential is Eη-Zn=-1.140±0.003 V, Efine-ζ=-1.052±0.003 V, and Ecoarse-ζ=-1.036±0.002 V. The presence of fine ζ phases can form a thick passivation film on the surface of the coating. The thickness of the passivation film for the outburst and flat ζ phase layers is 5.31 nm and 6.47 nm, respectively. The more uniform the distribution of fine ζ phases, the thicker the passivation film. The corrosion types of the outburst phase layer are mainly local corrosion and pitting corrosion, and the flat phase layer is mainly uniform corrosion. The corrosion products of η phase are ε-Zn(OH)2, 4Zn(OH)2.ZnCl2, Zn5(CO3)2(OH)6, and Zn5(Cl2)(OH)8.H2O. The corrosion products of ζ phase are Fe2O3, ZnO, and Zn(OH)2.

Untypical Electrochemical Corrosion Behavior of High-Nitrogen Austenitic Stainless Steel: Non-Pitting in Transpassivation

Untypical Electrochemical Corrosion Behavior of High-Nitrogen Austenitic Stainless Steel: Non-Pitting in Transpassivation

Comparison on the Electrochemical Corrosion Behavior of Ti6Al4V Alloys Fabricated by Laser Powder Bed Fusion and Casting.

The non-equilibrium solidification process in the additive manufacturing of titanium alloy leads to special microstructures, and the resulting changes in corrosion behavior are worthy of attention. In this paper, the microstructure and electrochemical corrosion behavior of Ti6Al4V alloys prepared using laser powder bed melting (LPBF) and casting are systematically compared. The results show that the LPBF-processed Ti6Al4V alloy is composed of dominant acicular α' martensite within columnar prior β phase, and less β disperses have also been discovered, which is significantly different from the α + β dual-phase structure of cast Ti6Al4V alloy. Compared to the as-cast Ti6Al4V alloy, LPBF-processed Ti6Al4V alloy has a thinner and unstable passive film, and exhibits slightly poorer corrosion resistance, which is mainly related to its higher porosity, a large amount of acicular α' martensite and less β phase compared to as-cast Ti6Al4V alloy. This result proves that suitable methods should be taken to control the relative density and phase composition of LPBF-processed Ti6Al4V alloys before application.

Microstructure, mechanical and corrosion property of neutron and γ-ray shielding (Gd2O3+W)/Al composites

In this study, a neutron and γ-ray absorbing (Gd2O3+W)/Al composite was fabricated by vacuum sintering. Firstly, through Monte Carlo Neutron and Photo Transport Code (MCNP) calculations, the content of Gd2O3 and W in the composite was determined to be 10 wt% and 25 wt%, respectively. Then, the influence of sintering temperature and sintering time on the microstructure, density, compression properties and electrochemical corrosion behavior of the (Gd2O3+W)/Al composites were investigated. The results indicate that sintering temperatures below 600 °C and sintering times shorter than 2 h led to insufficient density of the composite. Conversely, sintering temperatures above 600 °C and sintering times longer than 2 h caused W to agglomerate, resulting in a decrease in the density of the composite and a deterioration of its electrochemical performance. Therefore, the optimal sintering temperature and sintering time for the (Gd2O3+W)/Al composites were determined to be 600 °C and 2 h, respectively. Finally, the immersion corrosion performance in H3BO3 solution of the composite fabricated by the optimal process parameters was studied in detail. It was found that pitting was the main corrosion form of the (Gd2O3+W)/Al composite, and an oxidation film mainly composed of Al2O3 was formed on the surface.

Effect of solidification pressure on the corrosion behavior and mechanical properties of Al-7Si-3Cu-(0.4 Mg)-(0.5Ge) alloys

Developing practical microstructural solutions that simultaneously enable excellent corrosion resistance and mechanical properties in Al-Si-Cu-based alloys has been increasingly in demand. In this study, we attempt to tailor the microstructural evolution to manipulate the mechanical performance and corrosion resistance of Al-7Si-3Cu-(0.4 Mg)-(0.5Ge) alloys fabricated by GPa-level pressure combined with solution and/or aging treatments. It was found that as the solidification pressure increased, the dendritic growth tendency of the α-Al phase became less pronounced, and the modification of eutectic Si became increasingly significant. Complete solid solution alloys were even achieved under 6 GPa. The corresponding kinetic and thermodynamic mechanisms of pressure-induced microstructural evolution were explored in detail. Upon aging treatment, dense irregular Si precipitates emerged from the supersaturated matrix in Al-7Si-3Cu alloys solidified at 5 GPa and 6 GPa, while denser and finer Si precipitates growing along the 〈100〉Al directions dominated the matrix of Al-7Si-3Cu-0.4 Mg-0.5Ge alloys, which resulted in considerable enhancement of mechanical properties. The electrochemical corrosion behavior was evaluated in the as-cast and heat-treated conditions. The underlying corrosion mechanisms were discussed in terms of pressure, supersaturated solutes and precipitates. These results reveal the feasibility of designing high-strength and corrosion-resistant Al-Si-Cu series alloys via the manipulation of pressure and heat treatment.

Microstructural transformation and corrosion–cavitation behavior of ultrasonic nanocrystal surface modified nickel aluminum bronze (NAB)

In this study, nickel–aluminum bronze (NAB) is optimized by ultrasonic nanocrystal surface modification (UNSM), and its surface microstructural evolution, surface hardness, electrochemical corrosion behavior, and cavitation erosion behavior are investigated. The potentiodynamic polarization curves and electrochemical impedance spectra before and after UNSM treatment of NAB are measured using a typical three-electrode system. The cavitation erosion process is simulated through the vibration of ultrasonic waves underwater, and the cavitation erosion resistance performance of various specimens is evaluated. UNSM significantly refines the coarse and heterogeneous multi-phase structure of the cast NAB, providing a relatively uniform and dispersed structure. Simultaneously, severe plastic deformation rapidly increases micro-strains on the NAB surface, which effectively improves its surface hardness from 211 to 360 Hv. After UNSM treatment, the corrosion potential increases slightly; and the passivation potential and current decrease considerably, dropping from 207 to 103 mV and from 5.23 to 2.41 mA/cm2, respectively. This is primarily because of the slowdown of selective-phase corrosion and the uniform formation of an oxide film. Additionally, UNSM parameters affect corrosion potential by regulating surface roughness. A smoother surface corresponds to a higher corrosion potential at the same load. UNSM treatment significantly improves the cavitation corrosion resistance of NAB, primarily because an increase in hardness and uniform distribution of structure effectively slows the speed of crack formation and propagation, which is a result of the synergistic improvement of mechanical and corrosion resistance properties.

A review of physical properties of hot-dip galvanized coating layer by layer and their respective electrochemical corrosion behavior

PurposeThis paper aims to contribute to the performance improvement and the broader application of hot-dip galvanized coating.Design/methodology/approachFirst, the ability to provide barrier protection, galvanic protection, and corrosion product protection provided by hot-dip galvanized coating is introduced. Then, according to the varying Fe content, the growth process of each sublayer within the hot-dip galvanized coating, as well as their respective microstructures and physical properties, is presented. Finally, the electrochemical corrosion behaviors of the different sublayers are analyzed.FindingsThe hot-dip galvanized coating is composed of η-Zn sublayer, ζ-FeZn13 sublayer, δ-FeZn10 sublayer, and Γ-Fe3Zn10 sublayer. Among these sublayers, with the increase in Fe content, the corrosion potential moves in a noble direction.Research limitations/implicationsThere is a lack of research on the corrosion behavior of each sublayer of hot-dip galvanized coating in different electrolytes.Practical implicationsIt provides theoretical guidance for the microstructure control and performance improvement of hot-dip galvanized coatings.Originality/valueThe formation mechanism, coating properties, and corrosion behavior of different sublayers in hot-dip galvanized coating are expounded, which offers novel insights and directions for future research.

Corrosion behavior, metal ions release and wear resistance of TiN coating deposited on SLM CoCrMo alloy by magnetron sputtering

In this study, the TiN coating was successfully deposited on selective laser melting (SLM) CoCrMo alloy via magnetron sputtering technique. The TiN coating microstructure and thickness were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical corrosion behavior, metal ions release and wear resistance of the SLM CoCrMo sample with and without TiN coating was compared. The results showed that there was some macroparticles and pores on the TiN coating surface and the TiN coating thickness was about 1.44 μm. The TiN coating helped the SLM CoCrMo sample to reduce the corrosion current density from 19.1 nA/cm2 to 8.12 nA/cm2 and improved the corrosion resistance but not significantly. Then, an explanation of the corrosion resistance changes of the TiN coating was given. In addition, the TiN coating could prevent the metal ions release such as Co, Cr and Mo of the SLM CoCrMo sample at short time immersion but lost the protecting effect at long time immersion due to the corrosion damage of the TiN coating. Furthermore, compared to the SLM CoCrMo sample, the TiN coating was conductive to improving the wear resistance only at lower normal load (5 N) but had similar wear resistance at higher normal load (10 N and 30 N). The reason was mainly attributed to the thinner TiN coating thickness and higher load led to the failure of the TiN coating.

Effects of electrochemical corrosion on retrogressed and different reaged friction stir welded AA7075-AA6082 dissimilar welds

ABSTRACT The research is primarily to study the microstructure, tensile and electrochemical corrosion behaviour of friction stir welded AA7075-T651-AA6082-T6 dissimilar welds, subjected to retrogression and reaging at 280⁰C for 5 min followed by aging at 110⁰Cfor 1 , 5 , 10 and 24 h respectively. The AA7075-AA6082 welds were made using optimum parameters such as feed rate 80 mm/min, tool rotation speed 980 rpm, and tilt angle 2 o . The alloys of 100 × 50 × 6mm³ plates were welded with a conical tapered tool pin profile. Further, the welds were scanned for potentiodynamic polarisation with a 3.5 percentNaCl solution. Optical metallographic (OM) images were revealed to determine morphology andcorrelate with the measured corrosion rate. Here, the dissimilar friction stir weld AA7075-AA6082-aged for 5 h had an ‘Ultimate tensile strength’ (UTS) of 269.73N/mm2 due to coherent precipitates. Moreover, at 24 h, the lower tensile strength of 226.06 N/mm2 was observed, due to coarser precipitates across the AA7075-AA6082 weld cross-section. Due to over-aged coarse precipitates, the corrosion rate of 6082BM and weld metal had increased to 5.110e + 003mpy and 1.010e + 003mpy. Under other aged conditions, the corrosion rate was decreased below 0.001mpy.