Corrosion Conditions Research Articles

Study on the mechanism of different metal ions synergistic with alkali etching treatment in the flotation of lepidolite and feldspar

The two minerals were separated through alkali etching on the surface of lepidolite and feldspar, in conjunction with metal ion activation flotation. The activation of calcium (Ca2+) ion, magnesium (Mg2+) ion, copper (Cu2+) ion, and ferric (Fe3+) ion under alkali and non-alkali corrosion conditions was investigated, respectively. Micro-flotation experiments demonstrate that Ca2+ and Mg2+ can selectively recover lepidolite but not feldspar when the pH is above 6.5 during alkali etching. The activation of Cu2+ and Fe3+ flotation is not selective and can activate lepidolite and feldspar to some extent, irrespective of alkali etching. Through the valence bond theory, the selectivity of lepidolite and feldspar to dissolve and break bonds under alkali etching in a solution system was calculated. The adsorption differences and mechanisms of four types of metal ions were analyzed using solution chemistry, particle size analysis, and X-ray photoelectron spectroscopy (XPS) detections.

Evaluating the Impact of Environmental Factors on Corrosion Rates in Offshore Oil and Gas Pipelines: Insights from the Levantine Basin

The Levantine Basin is an important area for oil and gas exploration. However, the region's high salinity and corrosive conditions significantly threaten the durability of pipelines and equipment, resulting in substantial maintenance and repair expenses. This study seeks to evaluate the environmental and industrial influences on the corrosion rates of different oil and gas streams within the Levantine Basin. This study collected and analyzed data from the Levantine Basin, including physical and chemical properties of the streams, environmental factors such as temperature, pressure, and humidity. The Larkton corrosion software was utilized to simulate and predict corrosion rates under various conditions. Findings of this experiment demonstrate the significance of temperature on corrosion rates, showing a marked increase as temperatures rise. At lower temperatures, H₂S corrosion is more prominent, whereas CO₂ corrosion becomes the dominant factor at medium to high temperatures, especially when coupled with high CO₂ concentrations.

Bond performance of reinforcing bars in fly ash-based engineered geopolymer composites under uniform and nonuniform corrosion conditions

While concrete is the most popular building material in the world, corrosion of the steel reinforcement in reinforced concrete (RC) structures poses ongoing durability issues. In this study, the effects of alkali activator modulus, concentration, and different corrosion periods are rigorously investigated utilizing accelerated electrochemical corrosion techniques under both uniform and nonuniform corrosion conditions. Bond stress and bond stress deterioration are evaluated to provide a thorough examination of corrosion-induced fracture formation through pull-out experiments. X-CT 3D imaging is also used to understand the spread of rust in both corrosion scenarios. Results show that mixes with lower alkali activator modulus and higher alkali activator concentration might result in better bond stress preservation and higher ultimate bond stress under corrosion. High bond stress, however, usually corresponds to a more brittle failure when subjected to pull-out force. Nonuniform corrosion treatment can result in differential rust formation and a quicker bond breakdown between steel bars and engineered geopolymer composites (EGCs) than uniform corrosion. Furthermore, under corrosion, EGCs with high alkali activator modulus tend to form more penetrating cracks with limited width and depth. Both narrow and deep penetrating fractures can arise from EGCs with low alkali activator concentration.

An MeV Proton Irradiation Facility: DICE.

Materials applied in nuclear environments such as fission or fusion power-plants face severe conditions. The irradiation by neutrons induces thermal loads and irradiation damage. Furthermore, coolants in contact with the materials induce corrosion, which is particularly challenging for liquid salts intended for the next generation of fission reactors. A new device (DICE) is installed at the 3.5 MV accelerator at DIFFER for the accelerated testing of such materials under combined irradiation and corrosion conditions. The DICE enables irradiation of samples at temperatures of up to 1050 K and in contact with liquid salts. An integrated shielding and a low power temperature control concept based on radiation cooling enables high-duty cycle application in a standard accelerator laboratory. Ion currents of up to 30 µA are possible with continuous irradiation. This work outlines the technical concept of the device and presents the first data.

Leakage Quantification in Metallic Pipes under Different Corrosion Exposure Times

The combined effects of aqueous corrosion, stress factors, and seeded cracks on leakage in cast iron pipes have not been thoroughly examined due to the complexity and difficulty in predicting their interactions. This study seeks to address this gap by investigating the interdependencies between corrosion, stress, and cracks in cast iron pipes to optimise the material selection and design in corrosive environments. Leakage experiments were conducted under simulated localised corrosive conditions and internal pressure, revealing that leakage increased from 0 to 25 mL with crack sizes of 0.5 mm, 0.8 mm, 1 mm, and 1.2 mm, along with corrosion times of 0, 120, 160, and 200 h, and varying stress levels. An empirical model was developed using a curve-fitting approach to map the relationships among corrosion time, crack propagation, and leakage amount. The results demonstrate that the interaction between corrosion, stress, and crack propagation was complex and nonlinear, and the leakage amount increased from 0.7 to 0.10 mm every 15 min, as evidenced by SEM microstructure images and empirical data.

Ion-selectivity of galvanic corrosion products formed in multi-material gaps under atmospheric corrosion conditions with anti-freezing salts

Several multi-materials, which are joints of high-strength steels and lightweight materials such as aluminum alloy and carbon fiber reinforced thermoplastic, were subjected to the cyclic corrosion test for simulating atmospheric corrosion of automotive bodies and outdoor exposure tests. The ion-selectivity of the corrosion products formed in the multi-material gaps was examined by a membrane potential measurement. The corrosion products of all examined joints showed anion-selectivity rather than cation-selectivity. Corrosion products formed in joint gaps were less effective in preventing the progression of galvanic corrosion, suggesting that sufficient atmospheric corrosion protection is required for the use of multi-materials.

Pipeline Circumferential Cracking in Near-Neutral pH Environment Under the Influence of Residual Stress: Dormancy and Crack Initiation

The purpose of this study is to identify the integrity challenges encountered by buried pipeline steels, specifically to address Circumferential Near-Neutral pH Corrosion Fatigue (C-NNpH-CF). Damage to the pipeline’s protective coating and corrosion conditions increase the risk of service failures caused by C-NNpH-CF. (Note that this mechanism has previously been termed near-neutral pH stress corrosion cracking.) Unlike axial cracking, circumferential cracking is primarily influenced by residual stress from pipeline bending, geohazards, and girth welds. External corrosion pits often lead to dormant cracks, with growth ceasing around 1 mm depth due to reduced dissolution rates. Investigating the impact of bending residual stress (an appropriate source of axial residual stress) and cyclic loading (simulated pipeline pressure fluctuation), the study employs the digital image correlation (DIC) method for stress distribution analysis. Factors like applied loading, initial notch depth, and bending conditions influence crack initiation and recovery from the dormancy stage by affecting stress distribution, stress cells, and stress concentration. Cross-sectional and fractographic images reveal time/stress-dependent mechanisms governing crack initiation, including dissolution rate and hydrogen-enhanced corrosion fatigue. The study emphasizes the role of various residual stress types and their interactions with axial cyclic loading in determining the threshold conditions for crack initiation.

Effect of seawater corrosion on the mechanical properties of basalt fiber reinforced polymer composites modified by silane coupling agent KH560 and carboxylated carbon nanotubes

Basalt fiber reinforced composite (BFRP) has been widely used in various engineering fields, while the corrosion resistance of BFRP in harsh environments needs to be improved. In this work, the effects of seawater corrosion on mechanical properties of silane coupling agent (KH560) and carboxylated carbon nanotubes (CNTs) modified basalt fiber reinforced epoxy resin composites (BF/EP) were studied by simulating seawater corrosion under different conditions. The results showed that with the increase in corrosion time and temperature, the flexural performance and interlaminar shear strength (ILSS) of the composite material significantly decreased. Under the same corrosion conditions, the modified basalt fiber composite has better corrosion resistance to seawater than the untreated one due to an enhanced "soft-rigid" multi-scale stress transfer region between the BF and resin matrix. The flexural strength, flexural modulus and ILSS of modified basalt fiber composites decreased by 17.7 %, 12.2 % and 11.3 %, respectively, after 7 weeks of seawater corrosion at 60 °C, while that of untreated basalt fiber composites decreased by 28.2 %, 20.4 % and 19.7 %, respectively. In addition, the corrosion of distilled water on basalt fiber composites was also studied. Similarly, the modified basalt fiber composites showed better corrosion resistance to distilled water compared to the untreated basalt fiber composites. The research shows that the synergistic modification of KH560 and CNTs can effectively improve the corrosion resistance of BF/EP. This work is significant for promoting the development of BFRP and its application in marine environment.

Effect of corrosion on fretting wear morphology and mechanical behaviors of wires

Corrosion and fretting wear inevitably occur in wires, which are important parts of cables. To study the wear morphology and surface mechanical behavior of wires for different fretting and corrosion times, a numerical model of fretting wear of wire with different corrosion conditions is established using MATLAB and ABAQUS software’s. Firstly, according to the surface roughness of wires under different corrosion times, the node coordinates in the numerical model are modified to simulate different rough surfaces. Secondly, the wear characteristics of wires under different fretting cycles are obtained by using a cycle jump concept and an ABAQUS user subroutine. Finally, the numerical model is validated using experimental data. The results show that when the corrosion time is 0 h, the wear area has a regular oval shape. The wear volumes of wires with corrosion times of 120 h and 480 h are the largest and the smallest, respectively. As wear volume increases, both residual surface contact pressure and stress decrease. When the corrosion time is 0 h and 120 h, the residual surface contact pressure is maximum and minimum, respectively.

Thermal spray to embed optical fibers for the monitoring and protection of metallic structures

In the framework of using fiber optics (FO) for structural health monitoring, a true challenge is to fix the fiber onto structures guaranteeing both protection for the former and an effective adhesion on the latter. This work proposes a method to obtain such result via thermal spray technique on metallic structures, allowing its use in the most severe conditions of corrosion and wear. Since the transmission medium between the structure and the sensitive part of the optical fiber is represented by the fiber coating, three differently coated fibers were used on C-40 steel substrate: polyacrylate, polyimide and ORMOCER. In addition, the use of a primer to improve the bond on the substrate was evaluated. The adhesion between FO and metallic coating is evaluated through optical microscopy (OM) and scanning electrons microscopy (SEM) analysis. The functionality is also verified with both thermal and mechanical tests to calibrate the measuring accuracy. The results indicate that the best combination is that of the polyimide fiber, a zinc primer and aluminum coating. The proven qualities are the adhesion at the interface between the metallic coating and the fiber optics, and the preservation of the structural integrity of the fiber itself and its coating, and a precise measurement of strain acquired by fiber Bragg grating sensors (FBGs). The use of the thermal spray process is thus proved to be a solution for the optical fiber and substrate interaction, since it preserves the integrity of the optical fiber, due to the low temperature of the process, adding the protection that the metallic coating offers as well.

The static corrosion behaviors of gelcasted MAX phases in contaminated lead-bismuth eutectic (LBE) at 600 °C with low oxygen

The deployment of gelcasted MAX phase ceramic components in nuclear reactors is critical due to their exceptional performance. This study explores the corrosion behaviors of three gelcasted MAX phase ceramics (Ti3AlC2, Ti2AlC, and Ti3SiC2) in liquid lead-bismuth eutectic (LBE) at 600 °C under low oxygen conditions. Unique corrosion layers formed on the samples: Ti₃AlC₂ developed an Al2O3 inner layer and TiO2 outer layer, Ti₂AlC showed TiO2 grains coated with FeCr2O4 spinel, and Ti3SiC2 exhibited a composite layer of TiO2, Fe3O4, SiO2, PbO, and TiO2. LBE caused slight matrix enrichment in Ti₃AlC₂ and Ti₂AlC samples. Corrosion resistance was ranked as Ti3SiC2 > Ti3AlC2 > Ti₂AlC. Additionally, a coupled corrosion phenomenon resembling electrolytic electrodeposition between MAX phase ceramics and stainless steel was observed in contaminated LBE. This research provides novel insights into the corrosion mechanisms of MAX phases, paving the way for their application in advanced nuclear systems.

Corrosion and tribological properties of ta-C/ta-C: Ta coatings: Analysis of the influence of Ta-O/Ta-C ratio

Multilayer ta-C/ta-C: Ta coatings with varying total thicknesses (300, 600, and 1000 nm) and layer thickness ratios (1:0.5, 1:1, and 1:2) between the ta-C layer and ta-C: Ta layer were prepared. The study investigated the static corrosion resistance and tribological properties of the coatings in the NaCl solution. The static corrosion resistance positive correlation depended on the coating surface's Ta-O/Ta-C ratio. The lowest friction coefficient of 0.05 was obtained from the coating with a total thickness of 1000 nm due to the formation of the graphitized transfer film on the counterpart surface. A decreased sp2/sp3 ratio and the formation of tantalum oxide on the wear scar contributed to the lowest corrosion current, corrosive defect density, and wear rate.

Development and Adaptation of a Corrosion Inhibitor to Protect Metallic Equipment Under Carbon Dioxide Corrosion Conditions

Development and Adaptation of a Corrosion Inhibitor to Protect Metallic Equipment Under Carbon Dioxide Corrosion Conditions

Diagnostics and Prognostics of Pitting Corrosion in Large Civil infrastructure Using Multi-scale Simulation and Machine Learning

Corrosion, particularly pitting corrosion, represents a prominent form of deterioration in large infrastructure, characterized by its gradual and continuous capacity-reducing nature. As structures age, the need for assessing and monitoring corrosion status becomes increasingly crucial for system life-cycle management and optimal maintenance. However, the intricacies of the corrosion process pose challenges to effective diagnosis and prognosis. These challenges include the insufficient integration of mechanical stress into existing corrosion simulations, the computational intensity of most physics-based corrosion simulations hindering probabilistic studies and real-time predictions, and the difficulty in detecting pitting corrosion due to its localized nature, making it impractical to measure individual pits. This paper introduces a comprehensive prognosis and diagnosis framework applied to a miter gate case study. The framework seamlessly integrates multi-scale simulation, including mesoscale Phase-Field (PF) simulation and macroscale structural analysis, with Machine Learning (ML) methods to enable real-time corrosion diagnosis and prognosis. It facilitates efficient structural health monitoring (SHM) through a digital twin (DT) for corrosion damage. The core components of this framework encompass the development of multiscale simulation for simulating pitting corrosion in large structures, the construction of ML-based surrogate models to expedite simulations, image-based diagnosis, and the updating engine for prognosis.

Transfer learning applications for corrosion prediction for electrodissoluted specimens

Corrosion monitoring is a critical aspect of Structural Health Monitoring (SHM), as it presents inherent challenges in tracking its progression and requires strategically placed sensors for effective surveillance. Moreover, the intricate interplay between environmental factors and the material composition of corroding components further complicates this phenomenon. In this study, a novel neural network framework is designed to predict corrosion evolution based on environmental data, focusing on three distinct aluminium alloys: Al7475, Al2024, and F357. A dedicated neural network model is developed for Al7475, trained on electrodissolution data, including process parameters and profilometry measurements. This model predicts corrosion progression in terms of volume loss, corroded depth, and area based on charge measurements. To address the challenge of material-environment coupling, transfer learning is employed to adapt the neural network to Al2024 and F357. The oxidation charge passed during the electrodissolution mimics in an artificial way the corrosion process due to environmental conditions in the attack site. Consequently, the implemented neural network establishes a robust connection between corrosion process measurements and profilometry data, enabling accurate corrosion progression prediction based on oxidation charge. This framework allows the prediction of a component's residual useful life based on the assessment of the corrosion state, with the knowledge of volume loss further supporting mechanical assessment by evaluating resistant section or pit dimensions, ultimately aiding in the pit-crack transition analysis.

Fatigue Behavior of Flexural Reinforced Concrete Beams under Corrosion Conditions

Fatigue Behavior of Flexural Reinforced Concrete Beams under Corrosion Conditions

Resonant Eddy Current Sensor Design for Corrosion Detection of Reinforcing Steel.

This paper introduces an LC resonator-based single-frequency eddy current (EC) sensor designed for corrosion detection in reinforcing bars (rebars) embedded within concrete structures. The work addresses the challenges of the limited detection ranges and reduced sensitivity over longer distances, prevalent in current EC sensor applications. The sensor development process involved a systematic experimental approach to carefully selecting each parameter in the LC resonator. The sensor design aimed to assess the condition of the rebar from a distance of up to 5-6 cm outside the concrete and provide insights into different corrosion levels. By examining the characteristics of the inductors, the parallel resistance Rp of the eddy current coil was identified as a key parameter reflecting the corrosion conditions in the rebar. The relationship between the Rp fluctuations and temperature variations was investigated, with the data indicating that an approximately 155 Ω variation can be expected per 1 °C change within the temperature range of 20-25 °C, allowing for temperature compensation if necessary. Subsequently, the sensor's performance was evaluated by placing a rebar within a concrete block, where controlled mechanical degradation cycles were applied to simulate uniform corrosion in the rebar. The experimental results show that our EC sensor can detect material loss around the rebar with accuracy of approximately 0.17 mm.

The Effect of Corrosion on the Mechanical Properties (Diameter, Cross-Sectional Area, Weight) of the Reinforcing Steel

Corrosion of steel reinforcement is a major cause of deterioration in reinforced concrete structures, especially those located in marine environments. This study experimentally investigates the influence of corrosion on bond strength between reinforcing steel and concrete, as well as the effect on steel bar properties. Thirty-six concrete cubes reinforced with 12mm steel bars were prepared and subjected to varying corrosion conditions - non-corroded control, uncoated corroded, and coated with Anogeissus leiocarpus exudate. Specimens were immersed in 5% NaCl solution to accelerate corrosion, and tested at intervals up to 360 days. Pull-out tests showed bond strengths of corroded bars reduced by 25-30% compared to non-corroded controls. In severe cases, complete bond failure occurred in corroded specimens. Corrosion also led to reductions in bar diameter (0.04-0.05mm), cross-sectional area (0.5-1.3%), and weight (0.006-0.009kg) over time. Natural exudate coatings on steel mitigated these effects, restoring bond strength and limiting reductions to 0.01-0.02mm in diameter, and 0.003-0.005kg in weight. Graphical analysis correlated well with test data, clearly portraying deterioration trends under corrosion exposure. This study concludes corrosion causes significant weakening of bond integrity and property losses in reinforcement. Natural exudate coatings were found to effectively inhibit corrosion activity by restoring bond strength and protecting steel bars. With proper application, such eco-friendly coatings show promise as sustainable corrosion prevention alternatives for reinforced concrete infrastructure, especially in marine environments where corrosion accelerates more rapidly.

In-depth research on azole corrosion inhibitors - effect of N atoms position and quantity on copper corrosion inhibition performance in alkaline environments: Experimental evaluation and theoretical analysis

Copper's superior electrical properties make it ideal for multi-layer interconnections in integrated circuits. Chemical mechanical polishing (CMP) is the main method for achieving copper wiring flatness. However, copper is susceptible to corrosion in glycine-based alkaline polishing solutions. This study examines benzimidazole, indazole, and benzotriazole as corrosion inhibitors for copper in an alkaline environment (pH=9), focusing on the impact of nitrogen atom arrangement on inhibition efficiency. Through electrochemical, contact angle, static corrosion, and surface characterization tests, it's demonstrated that these inhibitors protect copper surfaces effectively. The adsorption of these inhibitors follows the Langmuir equation with a mixed adsorption mode. X-ray photoelectron spectroscopy (XPS), UV–vis spectroscopy tests, and density functional theory calculations elucidate the adsorption configuration and corrosion inhibition mechanism. The scope of this research extends beyond merely analyzing the performance of the three corrosion inhibitors; more importantly, it has yielded novel insights that are broadly applicable to the field of corrosion inhibitors. The findings are as follows: 1. The coupled structure of dinitrogen and trinitrogen facilitates charge accumulation, manifesting as the formation of additional Cu-N bonds, which prevents desorption; 2. The multi-nitrogen coupled structures provide sites for the formation of intermolecular hydrogen bonds, which is essential for the establishment of an orderly and dense passivation layer. It is expected that this study will provide valuable insights into the development and design of new and efficient copper corrosion inhibitors.

The Effect of Flow Velocity on Corrosion and Corrosion Mitigation of Carbon Steel in Wide Range of Sulfuric Acid Concentration

The impact of flow velocity (0-900 rpm) on the corrosion rate of carbon steel in a wide range of sulfuric acid concentrations (0-90% in H2O) at 30 °C and 1 h was studied and discussed. In addition, the efficiency of corrosion inhibitor (dimethyl disulfide, DMD) was evaluated in hardest corrosion conditions for the range of velocity investigated. The results revealed that increasing the flow velocity of H2SO4 solution, increases the corrosion rate depending on the acid concentration. When the flow velocity is increased of H2SO4 solution, the corrosion potential was shifted to more negative. The DMD inhibitors showed significant inhibition efficiency at high velocities, where the highest percentage of inhibitor efficiency reached 98% at 900 rpm.