Search

In the construction area, as well as in the restoration of old and historical buildings, different metallic materials are frequently in contact with gypsum plaster. Due to the high porosity of gypsum plaster, and particularly in high relative humidity environments, the risk of corrosion exists. In the present work, carbon, galvanized and stainless steel, as well as copper, were embedded in gypsum plaster (with varying water/gypsum ratios) and exposed to different environmental conditions, and the corrosion rate was assessed by electrochemical techniques. Stainless steel showed very low corrosion rates, carbon and galvanized steel showed considerable corrosion rates, and copper showed moderate corrosion rates. The higher the humidity, the higher the corrosion rate, independently of the water/gypsum ratio. A comparison with results obtained for the same materials embedded in mortar was performed. Except for stainless steel, the corrosion rates obtained in gypsum are higher than those obtained in mortar, being this difference up to two orders of magnitude. The differences in the pH of both matrices explained the lower corrosion rates measured in mortar. [ABSTRACT FROM AUTHOR]

Microbially influenced corrosion represents a critical challenge to the integrity and durability of carbon steel infrastructure, particularly in environments conducive to biofilm formation by nitrate-reducing bacteria (NRB). This study investigated the impact of NRB biofilms on biocorrosion processes within oil/water recovery operations in Algerian pipelines. A comprehensive suite of experimental and analytical techniques, including microbial analysis, gravimetric methods, and surface characterization, were employed to elucidate the mechanisms of microbially influenced corrosion (MIC). Weight loss measurements revealed that carbon steel samples exposed to injection water exhibited a corrosion rate of 0.0125 mm/year, significantly higher than the 0.0042 mm/year observed in crude oil environments. The microbial analysis demonstrated that injection water harbored an average of (4.4 ± 0.56) × 106 cells/cm2 for sessile cells and (3.1 ± 0.25) × 105 CFU/mL for planktonic cells, in stark contrast to crude oil, which contained only (2.4 ± 0.34) × 103 cells/cm2 for sessile cells and (4.5 ± 0.12) × 102 CFU/mL for planktonic cells, thereby highlighting the predominant role of injection water in facilitating biofilm formation. Contact angle measurements of injection water on carbon showed 45° ± 2°, compared to 85° ± 4° for crude oil, suggesting an increased hydrophilicity associated with enhanced biofilm adhesion. Scanning electron microscopy further confirmed the presence of thick biofilm clusters and corrosion pits on carbon steel exposed to injection water, while minimal biofilm and corrosion were observed in the crude oil samples. [ABSTRACT FROM AUTHOR]

In this work, leaves of Silybum marianum (L.) Gaertn were extracted by a one-step extraction method using ethanol as a solvent, and the Silybum marianum (L.) Gaertn extract (SMGE) was firstly employed as a green corrosion inhibitor for carbon steel in 0.5 mol/L H2SO4. The corrosion inhibition performance was studied using weight loss and electrochemical methods, and the anti-corrosion mechanism of SMGE is further analyzed through some surface characterizations and theoretical calculations. The results indicate that SMGE can act as a mixed-type corrosion inhibitor and possess superior corrosion inhibition performance for carbon steel in H2SO4 solution, and the optimum corrosion inhibition efficiency reached 93.06% at 800 ppm SMGE combined with 60 ppm KI. The corrosion inhibition efficiency increased with the rising inhibitor concentration. Surface characterizations illustrated that the inhibitor could physico-chemically adsorb on a metal surface, forming a hydrophobic, protective film. [ABSTRACT FROM AUTHOR]

The corrosion and material evaluation study in (a) water‐based simulated black liquor and (b) water‐based simulated black liquor at super‐critical conditions was successful. The conclusion from the testing program was that the most resistant alloy for the defined conditions is the chromium‐rich carbon steel candidate P91 (UNS K91560). This is a type of creep strength‐enhanced ferritic alloy, which is steel designed to retain strength at high temperatures. The P91 abbreviation represents the material's chemical composition, that is, 9 wt% chromium (Cr) and 1 wt% molybdenum (Mo). Further work is required to conclude the corrosion resistance for the P91 quality at supercritical conditions in the welded condition and to better understand caustic corrosion mechanisms. [ABSTRACT FROM AUTHOR]

Wear and corrosion of boiler tubes in coal-based boilers are one of the serious problems. Trying to solve this issue, FeCr alloy with 45%Cr-content coating and Fe-based coating with 13%Cr-content were arc sprayed onto carbon steel substrates to enhance both the wear and corrosion resistance of boiler heat exchanger pipelines. The microstructure, chemical compositions, and phases of the coatings were analyzed using a scanning electron microscopy, energy-dispersive spectrometer, and x-ray diffraction, respectively. The wear resistance of the coatings was assessed at 25 and 300 °C using a ball-on-disk wear tester. The corrosion resistance of the coatings was evaluated based on seawater immersion, electrochemical impedance, and polarization tests. The porosities of FeCr alloy and Fe-based coatings were 4.05 and 5.75%, respectively. The microhardness values of FeCr alloy and Fe-based coatings were 377.50 ± 46.88 HV0.5 and 666.69 ± 57.64 HV0.5, respectively. FeCr alloy coating with lamellar structure was mainly composed of FeCr solid solution phase and a small amount of Cr oxide and Fe3O4 phases, and Fe-based coating was composed of a mixture phase of amorphous and crystalline, and a small amount of Fe3O4 phase. FeCr alloy coating had better wear resistance than Fe-based coating at both 25 and 300 °C. The wear mechanisms of the coatings were also studied. The corrosion resistance of FeCr alloy coating was better than that of Fe-based coating in corrosive solutions. Therefore, FeCr alloy coating can provide better high-temperature wear resistance and anticorrosion performance for boiler heat exchanger piping, compared with Fe-based coating. [ABSTRACT FROM AUTHOR]

This study combines experimental and theoretical explorations. The corrosion inhibition performance of different concentrations (50, 100, 250, and 500 ppm) of folic acid in 3.5 wt% NaCl solution on Q235 steel was tested by weight loss and electrochemical test. The corrosion inhibition efficiency increased with the gradual increase of folic acid concentration and reached a maximum of 87% at 500 ppm folic acid. The experimental results for electrochemistry and weight loss are in good agreement with the simulation calculations. The adsorption of folic acid on the steel surface obeyed the Langmuir isotherm, and the adsorption process was a combination of chemisorption and physisorption. The contact angle test also yielded the maximum increase in hydrophobicity of the specimen surface at the added folic acid concentration of 500 ppm. The corrosion morphology after the addition of corrosion inhibitor was relatively flat. The adsorption orientation of folic acid molecules on the steel surface in an aqueous environment was investigated using density functional theory (DFT)/molecular dynamics (MD) simulations. The microscopic mechanism of action of folic acid corrosion inhibitors is clarified. [ABSTRACT FROM AUTHOR]

Methanol and hydrotreated vegetable oil (HVO) are complementary in the context of achieving ultra-low emission levels via low temperature combustion. HVO is a high-quality fuel fully compatible with compression ignition engines. Standalone methanol combustion is relatively straight-forward according to the Otto principle, with a spark ignited or in conventional dual-fuel ("liquid spark") engines. These two fuels have by far the largest reactivity span amongst commercially available alternatives, allowing to secure controllable partially premixed compression ignition with methanol–HVO emulsification. This study investigates the corrosion of aluminum, carbon steel, stainless steel, and a special alloy of MoC210M/25CrMo4+SH, exposed to different combinations of HVO, HVO without additives (HVOr), methanol, and emulsion stabilizing additives (1-octanol or 1-dodecanol). General corrosive properties are well determined for all these surrogates individually, but their mutual interactions have not been researched in the context of relevant engine components. The experimental research involved immersion of metal samples into the fuels at room temperature for a duration of 60 days. The surfaces of the metals were inspected visually and the dissolution of the metals into fuels was evaluated by analyzing the fuels' trace metal concentrations before and after the immersion test. Furthermore, this study compared the alterations in the chemical and physical properties of the fuels, such as density, kinematic viscosity, and distillation properties, due to possible corrosion products. Based on these results, methanol as 100% fuel or as blending component slightly increases the corrosion risk. Methanol had slight dissolving effect on aluminum (dissolving Al) and carbon steel (dissolving Zn). HVO, HVOr, and methanol–HVOr–co-solvents were compatible with the metals. No fuels induced visible corrosion on the metals' surfaces. If corrosion products were formed in the fuel samples, they did not affect fuel parameters. [ABSTRACT FROM AUTHOR]

A novel modified polyaspartic acid (PASP/CD) was synthesized from thiocarbazide and polysuccinim-ide. Secondly, the structure of PASP/CD was characterized by infrared spectroscopy (FT1R) and hydrogen nuclear magnetic resonance spectroscopy (NMR). Finally, the corrosion inhibition behavior of PASP/CD on carbon steel was studied by gravimetry, electrochemical method, atomic force microscope (AFM), contact angle and scanning electron microscope and energy spectrum (SEM/EDS) in 0.5 mol/L hydrochloric acid solution. The results show that when PASP/CD is added into hydrochloric acid solution as a mixed corrosion inhibitor, the charge transfer resistance of the system increases significantly. When the concentration of PASP/CD is 80 mg/L, the corrosion inhibition efficiency reaches 91.48%, which is much higher than PASP. Compared with PASP, the corrosion inhibition performance of PASP/CD is less affected by temperature. The figures and roughness data of AFM show that PASP/CD has good corrosion inhibition performance. It is found that the inhibition effect of PASP/CD is due to the physical and chemical adsorption of new functional groups on the steel surface. This work provides technical support for broadening the comprehensive properties of green water treatment agent polyaspartic acid. [ABSTRACT FROM AUTHOR]

The purpose of this study is to evaluate the corrosion resistance in natural seawater (Năvodari area) of two types of low-alloy carbon steels BVDH36 and LRAH36 by electrochemical methods. The electrochemical methods used were the evolution of the free potential (OCP), electrochemical impedance spectroscopy (EIS), polarization resistance (Rp) and corrosion rate (Vcorr), potentiodynamic polarization (PD), and cyclic voltammetry (CV). The studies were completed by ex situ characterization analyzes of the studied surfaces before and after corrosion such as: optical microscopy, scanning electron microscopy and X-ray diffraction analysis. The results of the study show us that the polarization resistance of the low-alloy carbon steel BVDH36 is higher compared to the polarization resistance of the low-alloy carbon steel LRAH36. It is also observed that with the increase in the immersion time of the samples in natural seawater, the polarization resistance of the BVDH36 alloy increases over time and finally decreases, and for the carbon steel LRAH36 the polarization resistance increases. [ABSTRACT FROM AUTHOR]

To achieve the necessary mechanical properties and high corrosion resistance, heat treatment is based on a significant alteration in the microstructure of metals and alloys. The metal is heated above a critical temperature during heat treatment processes. Several methods, such as quenching and cooling in various media, followed by tempering and other heat treatment operations, can be used to achieve this. Steel can be made more malleable by annealing, which also increases ductility and improves corrosion resistance. In this study, thirty medium carbon steel specimens were used, which were split into different groups, various heat treatments were applied. First quenching, first tempering, second quenching, and second tempering were among the heat treatment procedures used, and cooling media made of distilled water were used at various temperatures. After that, the corrosion rate in these specimens was looked at, and the results were compared to the corrosion rate in the base specimen. The results show that repeated heat treatment of the metal generally lowers the rate of corrosion in the metal, particularly when distilled water is used for the cooling process after the two tempering stages at a temperature of almost absolute zero. The findings show that the second sample had the lowest corrosion rate of all the samples. When compared to the corrosion rate in the basic sample, the corrosion rate in this sample decreased by about 92.9%. [ABSTRACT FROM AUTHOR]

The comparison of different grades of carbon steel (API 5L X52 and X60) dissolution in CO2–H2S solution at various acetic acid concentrations was investigated via electrochemical experiments and other complementary techniques such as FESEM, XPS and contact angle measurements. The results are evident to suggest that the carbon steel grade strongly influences corrosion rate as X60 corrodes more than X52 in the system being investigated. The possible mechanism behind the higher corrosion rate observed for X60 is elucidated via analyzing the impedance data acquired at various overpotentials by the reaction mechanism analysis approach. The kinetics of dissolution in the given medium for the carbon steels is also reported. It is observed that X52 possess higher surface energy (lower contact angle), which eventually increases the formation rate of FeCO3 on X52. The FeCO3 layer formed on X52 is fine in nature, acts as a protective layer and decreases the corrosion rate. [ABSTRACT FROM AUTHOR]

Urgent action is required to mitigate the severe corrosion of carbon steel in low-latitude regions. The combination of high humidity, temperature, and salinity in these areas significantly accelerates steel corrosion, posing a substantial threat to the service safety of offshore engineering equipment. This study aims to elucidate the atmospheric corrosion mechanisms of 45# steel in low-latitude coastal areas. Samples of 45# steel were exposed to atmospheric conditions over various durations in the following three geographically distinct regions: Guangzhou, Wanning, and the South China Sea. The corrosion rates were calculated using weight loss tracking and potentiodynamic polarization measurements, while surface corrosion products were examined using X-ray diffraction (XRD) tests. The findings indicate a clear correlation between the corrosion rate of 45# steel and the latitude and specific location of the test area, with the highest to lowest rates observed in the South China Sea, Wanning, and Guangzhou, respectively. Similarly, the extent of corrosion rust penetration in defective coatings followed the same order. Moreover, the protection ability index (PAI) calculations revealed that none of the tested samples formed a protective corrosion film. [ABSTRACT FROM AUTHOR]

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

For CCR unit that employ dry cooling cycles for catalyst regeneration, regenerative recycle gas drying is an indispensable system in continuous catalytic reformers. In recent years, corrosion and leakage problems have occurred many times, which seriously affects the long-term operation of the unit. An analysis was conducted on the corrosion causes of the internal coolers, separators and connecting pipelines in the regeneration cycle gas drying system of four continuous reforming units. It was found that the main causes of corrosion were acidic gas dew point corrosion and circulating water corrosion. In response to the current corrosion situation, a series of control measures to extend the operating cycle are proposed in the following text. Increasing the inclination angle for the installation of the inlet and outlet of the heat exchanger shell in the process design, and adding filters. Add fiberglass or PTFE lining to the separator and connecting pipes in the material selection, and add coating anti-corrosion to the carbon steel pipe bundle of the water cooler; Control the quality of circulating water in operation, strengthen monitoring of process parameters and corrosion conditions. [ABSTRACT FROM AUTHOR]

Cathodic protection is an electrochemical technique used to control the corrosion of metals. It does this by sending a proper amount of current equal to the current required by the cathodic processes at the protection potential. One of the chemical effects of cathodic protection is a local pH increase at the surface, which is an important factor in the reduction of corrosion rate, as carbon steel may work in a passive condition. In the present study, a tertiary current distribution finite element method model is introduced. A dynamic boundary condition is considered, by defining a Fe anodic Tafel slope as a pH function, and oxygen reduction reaction limiting current density as a function of available oxygen at the cathode surface. The model has been validated by direct pH measurement during a short‐term polarization test, and subsequently used to predict the pH and the available oxygen at the cathode surface for long‐term condition. [ABSTRACT FROM AUTHOR]

In Northern Chile, large amounts of highly corrosive solutions are currently generated in the process of cathode washing after completing the electrowinning or electrorefining process of copper. This study investigates the electrochemical behavior of ASTM A36 carbon steel in pregnant-leach-solution (PLS) wash water. Measurements of electrochemical impedance spectroscopy and linear sweep voltammetry, complemented with weight loss measurements, were performed. Four ratios of PLS containing reverse osmosis (RO) water are evaluated, considering both quiescent and rotating conditions of the steel specimen. The results indicate that oxygen reduction, hydrogen evolution, and iron oxidation reactions are all involved during the corrosion of carbon steel in pure RO water, with the corrosion rate increasing up to 4 times under rotating conditions. In the case of corrosion in RO wash water containing PLS, a galvanic process occurs whereby copper is reduced at the expense of iron oxidation, superimposed on former partial reactions. The deposited copper induces notable corrosion inhibition of steel, observed as a significant drop in corrosion rate from high initial to constant residual values. Morphological and X-ray analyses support that corrosion is affected by oxide layer formation and galvanic copper deposition, confirming the results obtained from electrochemical analysis and weight loss measurements. [ABSTRACT FROM AUTHOR]

Electrochemical Impedance Spectroscopy (EIS) is a non-destructive and powerful technique for characterizing corrosion systems, allowing for the evaluation of surface reaction mechanisms, mass transport, kinetic evolution, and corrosion levels of materials. This study aims to analyze the progression of corrosion using EIS, with a focus on the influence of organic coating thickness. For this purpose, layers of high-purity epoxy paint were applied to carbon steel plates with thicknesses of 50 µm, 80 µm, and 100 µm. During the research, a direct correlation was observed between coating thickness and corrosion resistance, emphasizing the importance of identifying the optimal thickness for each type of coating. Additionally, it was found that thicker coatings may experience electrode penetration due to the tensions generated during deposition, resulting in cracks between the layers, while thinner coatings allow electrolyte penetration as they do not provide adequate protection to the base steel. Therefore, the 80 µm thickness demonstrated greater resistance to corrosion compared to the other tested thicknesses. [ABSTRACT FROM AUTHOR]

Photocathodic protection (PCP) technology has gained wide attention in the field of corrosion due to its green, environmentally friendly, and sustainable characteristics, and has become a protection technology with broad development prospects in the future marine environment. By investigating recent research results, the mainstream photoanode materials are TiO2, BiVO4, g-C3N4, ZnO, In2O3, SrTiO3 and other materials. Among them, TiO2 is an ideal photoanode material for PCP because of its efficient photochemical corrosion resistance, remarkable reaction stability, and excellent photoelectric properties. However, TiO2 itself has more drawbacks, such as limited utilization of visible light and low photogenerated electron-hole separation efficiency. These defects limit the wide application of TiO2 in PCP. Through modification methods, the reaction efficiency can be substantially improved and the availability of TiO2 can be increased. This paper lists the research progress of modifying TiO2 materials using metal and non-metal doping modification, semiconductor compounding technology, and energy storage materials for application in PCP, and introduces several new types of photoanode materials. This paper suggests new ideas for the design of more efficient photoanodes. [ABSTRACT FROM AUTHOR]

For high-level radioactive waste, the French National Radioactive Waste Management Agency is currently developing a 500 m deep geological disposal facility called Cigéo. Carbon steel containers will be used to contain the wastes in the specific conditions of the disposal. The use of a sacrificial coating was studied as an additional protection for the containers against corrosion. A previous work had shown the possibility to use Zn-Al coatings in this specific medium. To optimize the coatings' performance, the cold-spraying process was considered instead of the previously used wire arc spraying because it can increase the cohesion between the particles in the coating. Moreover, three aluminum contents, i.e., 5, 15 and 25 wt.%, were considered. The characterization of the obtained coatings revealed a strongly heterogeneous composition for the lower Al content (5 wt.%), with local Al contents from 1.3 wt.% Al to 44.5 wt.% Al. The corrosion study was carried out in a specific solution mimicking the pore solution of the surrounding cementitious material designed for disposal at a temperature of 50 °C. First, the polarization curves acquired with coated steel electrodes revealed the pseudo-passive behavior of the 25 wt.% Al coating, while for the other compositions, the coating remained active. Moreover, the higher aluminum content (25 wt.%) induced an important decrease in potential, with a possible risk of hydrogen embrittlement for the protected steel. Secondly, the sacrificial properties were investigated through 6 months of experiments using coated electrodes with cross-like defects and coated electrodes coupled with bare steel electrodes. Whatever the composition of the coating, the protection was maintained, with the 15 wt.% Al coating giving the best performance. [ABSTRACT FROM AUTHOR]

Co3O4 nanoparticles (Co3O4-NPs) are synthesized using the facile solvothermal method. FT-IR and XRD spectroscopic analyses verify the creation of cobalt oxide nanoparticles with an average size of 13.20 nm. Furthermore, Zeta potential assessments were carried out to identify the electrical charge of the surface of the produced Co3O4-NPs, which was found to be -20.5 mV. In addition, the average pore size of Co3O4-NPs is 19.8 nm, and their BET surface area is 92.4 m/g. The study also concerned the effect of Co3O4-NPs on epoxy's improvement of mechanical and corrosion protection for carbon steel in salt solution. By including Co3O4-NPs in an epoxy (EP) coating, corrosion is effectively prevented by non-permeable protective coatings that effectively reduce the transfer of corrosion ions and oxygen. [ABSTRACT FROM AUTHOR]

The efficacy of alumina-sol based coatings in a water-free atmosphere at high temperatures suggests a potential solution for enhancing the corrosion resistance of high-alloyed steels in Carbon Capture and Storage (CCS) environments. In this study, coupons of X20Cr13, designed for use as injection pipes with 13% Chromium and 0.20% Carbon (1.4021, AISI 420), were sol-gel coated with water and ethanol-based alumina. These coated coupons were then exposed to CO2-saturated saline aquifer water, simulating conditions in the Northern German Basin, for 1000 h at ambient pressure and 60 °C. Corrosion fatigue experiments were also conducted using specimens of X5CrNiMoCuNb16-4 (1.4542, AISI 630), a suitable candidate for geothermal applications, to assess the impact of the ethanol-based coating on the number of cycles to failure at different stress amplitudes. Unfortunately, the coating exhibited early spallation, resulting in corrosion kinetics and corrosion fatigue data identical to those of uncoated specimens. Consequently, the initially promising Boehmit coating is deemed unsuitable for CCS applications and further research therefore not advisable. [ABSTRACT FROM AUTHOR]

Passive surface acoustic wave (SAW) devices are attractive candidates for continuous wireless monitoring of corrosion in large infrastructures. However, acoustic loss in the aqueous medium and limited read range usually create challenges in their widespread use for monitoring large systems such as oil and gas (O&G) pipelines, aircraft, and processing plants. This paper presents the investigation of impedance-loaded reflective delay line (IL-RDL) SAW devices for monitoring metal corrosion under O&G pipeline-relevant conditions. Specifically, we studied the effect of change in resistivity of a reflector on the backscattered signal of an RDL and investigated an optimal range through simulation. This was followed by the experimental demonstrations of real-time monitoring of Fe film corrosion in pressurized (550 psi) humid CO2 conditions. Additionally, remote monitoring of Fe film corrosion in an acidic solution inside a 70 m carbon steel pipe was demonstrated using guided waves. This paper also suggests potential ways to improve the sensing response of IL-RDLs. [ABSTRACT FROM AUTHOR]

The Al-5Mg alloy coatings were fabricated by the twin-wire arc thermal spray on the SS400 steel substrate using various spraying parameters. The surface morphology of the coatings was examined using field emission scanning electron microscopy (FE-SEM). The porosity of the coatings was investigated by image analysis according to ASTM E2109-01 standard. The corrosion behavior of the coatings immersed in 3.5 wt.% NaCl solution was investigated by electrochemical polarization scanning and electrochemical impedance spectroscopy measurement. The study results showed that the coating deposited with a spray mode consisting of current of 300 A, pneumatic pressure of 5.5 bar, and standoff distance of 160 mm has higher Al and Mg elemental content than the coating fabricated with other spray parameters. The porosity of the coating varies from 7.38 to 11.82%, depending on the spray mode. The corrosion mitigation of the Al-Mg alloy coating was considerably enhanced due to higher contents of Al and Mg, a homogeneous surface, and low porosity. [ABSTRACT FROM AUTHOR]

Submersed downhole pump systems used in oil industry field are working and subjected to attacker environment. Rich aquas, chloride, and sulfide environments present a tough chemical condition. This work investigated a failure case study of two submersed downhole pumps that were worked in sea water in oil industry. Pump 1 and pump 2 failed after 196 and 60 days, respectively. Every pump had head and hosing made from carbon steel and compression ring made from stainless steel. Compression ring was not affected by corrosion, but head and housing were. Investigations were made for carbon steel head and housing by mechanical analysis, visual examination, optical microscope, and scanning electron microscope (SEM) for imaging and EDS. Results show a corrosion for the whole surface of two pumps and pitting corrosion in many positions. Many corrosion products are formed such as FeCO3, Fe2O3, and FeCl3. The corrosive products were the main reason for failure which formed due to working conditions and environment. [ABSTRACT FROM AUTHOR]

Clean-integrity processing of nuclear-grade AISI 316L austenitic stainless steel components finished by the wire brush and sequent flap discs is performed for high-performance manufacturing of the nuclear power plant equipment. Two steel wire brushes of AISI 304 austenitic stainless steel and 65Mn carbon spring steel are used for the grinding under a spindle speed of 550–2000 rpm. Sequent polishing is carried out by the flap discs using silicon carbide cloth under 2000 rpm. An equivalent pitting corrosion resistance to that of the original stainless steel in 3.5% NaCl solution is obtained for finished samples by the combined processes. The contaminants composition of ground stainless steel samples is determined by the redness degree of chromaticity inspection. The contaminants microstructure and finishing-induced microstructure are dependent on the impedance phase angle change in eddy current impedance diagrams. The surface clean-integrity of nuclear-grade stainless steel is characterized by the series of nondestructive evaluation methods. [ABSTRACT FROM AUTHOR]

Pipelines are structures with great relevance in different industrial sectors and are essential for the proper functioning of the logistics that support today's society. Due to their characteristics, locations, and continuous operation, allied with the huge network of pipelines across the world, they require specialized labor, maintenance, and adequate sensing systems to access their proper operation and detect any damage they may suffer throughout their service life. In this work, a fiber Bragg grating (FBG)-based optical fiber accelerometer (OFA), which was designed and calibrated to operate through wavelength and optical power variations using different interrogation setups, was fixed together with a pair of FBG arrays along a 1020 carbon steel pipeline section with the objective of monitoring the pipeline natural frequency (fn_pipeline) to indirectly evaluate the detection and evolution of corrosion when this structure was buried in sand. Here, corrosion was induced in a small area of the pipeline for 164 days, and the OFA was able to detect a maximum fn_pipeline variation of 3.8 Hz in that period. On the other hand, the attached FBGs showed a limited performance once they could successfully operate when the pipeline was unburied, but presented operational limitations when the pipeline was buried in sand. This was due to the inability of the structure to vibrate long enough under these conditions and obtained data from these sensors were insufficient to obtain the fn_pipeline. [ABSTRACT FROM AUTHOR]

The package of the applied programs with base of the thermodynamic data is used and the theoretical analysis of physical and chemical conditions of complex- saturation carbon steel by silicon and chrome in medium of chlorine in the closed reactionary space is carried out at the lowered pressure of a gas phase. Simultaneous saturation of steel 40 with chrome and silicon in chlorine atmosphere for 6 hours at a temperature of 1323 K and a pressure of 102 Pa of the gas phase is carried out in this work. By means of the x-ray diffraction studies, it is found that, under the assumed conditions of saturation on the steel 40 surface, diffusion layer with thickness of 100-110 µm is formed, which corresponds to the phase of the corresponding chromium carbides Cr23C6 and Cr7C3 doped with silicon, and a solid solution of chromium and silicon in α-iron. The corrosion studies carried out in this work show that chromosilicide coatings applied onto carbon steel 40 are less stable in solutions of 10% hydrochloric and sulphuric acids, and the most stable in solutions of nitric acid. [ABSTRACT FROM AUTHOR]

This study examined the effects of hot rolling on the microstructure, tensile strength, and corrosion behaviors of three different alloy steels made by powder metallurgy: Fe-0.55C, Fe-0.55C-3Mo, and Fe-0.55C-3Mo-10Ni. 700 MPa pressure was applied to press the particles. The cold pressed samples were sintered in a mixed-gas atmosphere (90% nitrogen, 10% hydrogen) at 5°C/min up to 1400°C for 2 hours. Then, the produced steels were hot rolled with a deformation rate of 80%. The microstructures show that deformed Mo and Mo-Ni steels have finer microstructures, better mechanical properties than undeformed Mo and Mo-Ni steels, and MoC, MoN, or MoC(N) was formed in the Mo-Ni steels. The highest mechanical properties were obtained in rolled steel samples containing Mo-Ni, followed by rolled Mo steel and rolled carbon steel samples, and then unrolled samples. Additionally, Tafel curve analysis demonstrated that alloy corrosion resistance rose as Ni concentration increased. It has also been observed that the hot rolling process improves corrosion resistance. The increase in the density value with the rolling process emerged as the best supporter of corrosion resistance. [ABSTRACT FROM AUTHOR]

Japanese tap water is Ca2+-poor and SiO2-rich in comparison with that of other counties. Thus, there have been few studies on its corrosivity. We sampled tap waters at 70 different sites and in different seasons in Japan, subjected the samples to chemical analysis and measured localized corrosion depth and the total corrosion loss of carbon steel placed in these waters. The average corrosion rate vavg and maximum localized corrosion rate vmax were calculated. The ratio of vmax to vavg, which was defined as localized corrosion factor LCF (=vmax/vavg), was also studied. The multiple regression method was applied to obtain the dependence of vavg (objective variable) on concentrations of chemical species (explanatory variables). In the same manner, the relation of vmax and LCF to concentrations of chemical species was derived. As a result, we showed that SiO2 and SO42− mainly dominate the corrosivity of Japanese tap water. In particular, as SO42− increased, vavg became larger and vmax became smaller. Also, as SiO2 increased, vmax became larger and vavg became smaller. The behavior of LCF was similar to that of vmax. The findings of this study will be useful for estimating the corrosivity of tap waters that have low Ca2+ and high SiO2 concentrations. [ABSTRACT FROM AUTHOR]

In this work, the main object of this research is to investigate a new material based on ZnS and NiS nanostructures. NiS and ZnS solutions were sprayed on the heated Low Carbon Steel by a spray pneumatic deposition method. Electrochemical analyses of the prepared samples were investigated. The high corrosion resistance of coated by ZnS sample have a low value of surface roughness. However, the coated sample by ZnS also has good stabilization after corrosion and high compact of the film. [ABSTRACT FROM AUTHOR]

To increase the performance of the compound casting, the corrosion-wear behaviour of a Zinc Silicate coating on the surface of IS 2062 Grade B Carbon Steel using high velocity oxygen fuel spraying is assessed. The microstructure and mechanical properties of the Zinc Silicate coating, as well as its thickness, were investigated. . Scanning Electron Microscope (SEM), X-ray Diffractometer (XRD), surface roughness, and co-efficient of friction were used to investigate the coating's corrosion behaviour. From the perspectives of powder qualities and process parameters, the relationship between microstructure and mechanical properties of coatings was explored. When compared to uncoated materials, experimental results revealed that the microstructure of the coating was noticeable, and the wear properties are also improved. [ABSTRACT FROM AUTHOR]

The present study covers the failure of a stainless-steel firefighting system after three months of completion and operation. The system used seawater with chemical foaming additions. The investigation revealed the low quality of the used material. Corrosion pits propagated by tunneling parallel to the pipe axis. Tunneling is a common mechanism of damage propagation in microbiologically influenced corrosion (MIC) in carbon steels, but interestingly tunneling is reported in this case in stainless steel. The root cause of this damage is the use of bacteria-infected water/fluid inside the piping system. To avoid such damages in the future, some recommendations are suggested. It is recommended that (i) the firefighting fluid is treated to reduce the aggressive contaminant levels; (ii) for the damaged piping system, it might be a solution to use a broad-spectrum biocide to penetrate and destroy the biofilms and stop the damage; and (iii) use of other alloys rather than the austenitic stainless steel may constitute a feasible remedy for this failure, as well. [ABSTRACT FROM AUTHOR]

In this work, magnetic responses from artificial corrosion defects were investigated using a differential fluxgate probe. Different rates of corrosion defects were prepared based on the electrolytic corrosion process on the surface of a carbon steel plate by manipulating the corrosion period. Then, the differential fluxgate probe, consisting of two miniature fluxgates arranged in a planar configuration and a circular excitation coil, was used to measure the real and imaginary components of magnetic responses from the corrosion defects in the range of 5 to 510 Hz. The real differential magnetic response from the probe showed that the magnetic signal change was proportionally increased with the corrosion period, revealing the increased depth of the corroded region with the electrolytic corrosion period. The magnetic response induced by an excitation field from 10 to 110 Hz could be utilized to enable a sensitive depth estimation of a corrosion defect on high-permeability steel at a sub-millimeter resolution. [ABSTRACT FROM AUTHOR]

The effect of the benzimidazole-2-ylcarbamate methyl (Carbendazim) in corrosion inhibition for carbon steel has been studied using stationary and transient electrochemical techniques. The potentiodynamic curves show that Carbendazim acts as a mixed-type inhibitor. The electrochemical impedance diagrams show a capacitive response of carbon steel with and without inhibitors at different concentrations in 1M HCl. The polarization resistance increases with increasing inhibitor concentration. Consequently, the inhibition efficiency increases and reaches 84% at 10-2M and its adsorption follows the Langmuir isotherm. This shows that the protective effect of Carbendazim is significant in an acidic medium. The study of the synergistic effect with KI shows that an equimolar mixture of KI and Carbendazim compound enhances the inhibition efficiency. The theoretical investigation of the tested compound ability to inhibit corrosion using DFT shows that the HOMO, LUMO, and electrostatic potential maps surfaces can qualitatively identify the most nucleophilic and electrophilic centers, this will enable us to give an adsorption mechanism for the inhibitor studied on the metal surface. [ABSTRACT FROM AUTHOR]

High-temperature coatings play a crucial role in protecting surfaces exposed to extreme temperatures, corrosion, and other harsh environments. This paper focuses on the physical and chemical properties of solvent-borne and water-borne high-temperature silicone-based polymer coatings applied on two types of surface roughness of carbon steel plates. The corrosion protection performance of the coatings was characterized using a salt spray chamber, humidity chamber, electrochemical impedance spectroscopy (EIS) measurements, and differential scanning calorimetry (DSC). The physical properties of high-temperature coatings were determined using the Shore D hardness method and cross-cut adhesion tests. This study investigates the effects of different surface preparation methods on coating adhesion, which is considered to be a crucial property of organic coatings for corrosion protection durability. The thermal stability of the coating was tested using furnace cyclic testing. The results show that high-temperature coatings in general exhibit excellent thermal stability, high adhesion strength, and good resistance to warm and humid environments, except in the conditions of a salty atmosphere. This study reveals that coating performance is affected by the composition and surface preparation method. This study can be useful for coating manufacturers and researchers interested in understanding the physical and chemical properties of high-temperature coatings and their applications in various environments. [ABSTRACT FROM AUTHOR]

Zn-Al coatings have attention to corrosion resistance in marine environments. In this study, Zn and Al single coatings, and Zn-Al mixed coating were obtained by an arc spray technique on carbon steel substrates. Zn and Al coatings comprised single Zn and Al phases, and some oxides. Zn-Al coating was composed of 46 at.% Al, 53 at.% Zn, and a few of oxygen. Zn-Al coating was a pseudo-alloy coating mechanically mixed with Zn, Al, and alloy phases. The cross-sectional microhardness values of Zn, Al, and Zn-Al coatings were 173.8 HV0.5, 181.69 HV0.5, and 259.88 HV0.5, respectively. The friction coefficients of Al, Zn, and Zn-Al coatings were 0.7, 0.55, and 0.5, respectively. The wear and corrosion resistances of Zn-Al coating were better compared with single metallic coatings. The corrosion mechanisms of single Zn, Al coatings, and Zn-Al coatings were addressed and studied. Zn-Al coating could offer better wear resistance and anticorrosion performance for marine engineering steel, compared with Zn and Al coatings. [ABSTRACT FROM AUTHOR]

The ethanolic extract of Lentinula Edodes, a fungal species, was evaluated as an ecological, green inhibitor to mitigate corrosion of carbon steel (CS) in acidic media. The Lentinula Edodes body fruit extract (LEBFE) was obtained using a well-established chemical method. Various electrochemical methods were employed to investigate the LEBFE's corrosion inhibition efficiency under different operating conditions. The results showed that LEBFE is an effective mixed-type corrosion inhibitor, with a maximum corrosion protection efficiency 88.5 ± 0.2%. The inhibitor demonstrated efficient corrosion inhibition of the carbon steel surface over extended immersion periods and at various electrolyte temperatures. The FTIR and UV/Vis results indicated that the LEBFE extract contains compounds containing oxygen and nitrogen heteroatoms, which are known to interact strongly with carbon steel. The adsorption mechanism of the inhibitor on the carbon steel surface was based on physisorption, following the Langmuir isotherm. The results support the conclusion that LEFBE can be considered an effective and eco-friendly green inhibitor to control low-carbon steel corrosion in acid media. [ABSTRACT FROM AUTHOR]

In seawater, carbon steels suffer severe corrosion damage that causes significant economic losses. To control this damage, the use of cathodic protection is essential, an effective method generally favored by calcareous depositions on the metallic substrate when the structures are submerged. To analyze the kinetics of these deposits on different metals, large perturbations of potential, temperature, ion content, etc. have been applied in the laboratory. However, a study of the variability of physicochemical parameters with real values focused on measuring the efficiency of the protection systems operating with a real protection criterion, had not been carried out. This research contemplated the previous objection as its aim. To achieve it, a multiple impressed current cathodic protection system was used to ensure the integrity of API X70 steel specimens by the same protection potential. Using electrochemical techniques (RP, EIS, and CP) and scanning electron microscopy (SEM) techniques, the efficiency of these systems was determined in correlation with the evolution of calcareous deposits. The results revealed that normal seawater conditions and their slight variations provide tolerant environments for performing the protection systems, with maximum deficiencies of - 52% and benefits of up to 59% (considering 0% normal operation conditions). Micrographs corroborated all the calcareous products formed got with SEM. This work showed that the physicochemical variability of seawater affects the performance of cathodic protection and that we need new criteria to counteract these effects. [ABSTRACT FROM AUTHOR]

The alloys of the aluminum bronze system contain 5–14wt% Al that can be heat treated giving as result of different microstructures that were characterized by optical microscopy and scanning electron microscopy. This work aimed at investigating the influence of the microstructures of a Cu-9Al-3Ag alloy obtained after normalizing and annealing heat treatments, on the corrosion behavior in a saline medium containing 0.5 M sodium chloride, NaCl. The corrosion effect on the phases compounding the overall microstructures as result of immersing the samples in the corrosive medium was evaluated using cyclic voltammetry, potentiodynamic polarization curves, and electrochemical impedance spectroscopy. The results showed that normalizing and annealing heat treatments redefined the distribution of the α phase and, in addition led to formation of proeutectoid pearlite (α + γ2), which is a microstructural constituent configured similarly to that present in diverse carbon steels, though in this case displaying a sequence of alternate lamellae of α and γ2, respectively. From the results of the linear polarization plots, the maximum anodic potentials became apparent, just like the regions where the trend of the graph gave the impression that passivation were to gain control. Likewise, the Tafel plots and impedance tests evidenced that the as-cast and normalized samples exhibited a better resistance to corrosion, at variance with the results of the annealed sample. [ABSTRACT FROM AUTHOR]

In this research, the contribution of silicon-based nanoparticles (NP) applied superficially on steel–concrete systems, for the passive film improvement was studied. The steel–concrete system was evaluated by electrochemical behavior and durability (physical and chemical properties) generated after such treatment. Corrosion current density (icorr), electrochemical double-layer capacitance (Cdl), coefficient of Warburg impedance (σw), film resistance (Rfilm), and total pore volume were some of the indicators to assess the contribution of NP on the passivity behavior of steels. The systems were fabricated with AISI 1018 carbon steel (CS), and AISI 1018 galvanized steel (GS) embedded in concrete. The water/cement ratio of 0.45 after concrete cured in a dispersion of NP for 24, 48, and 168 h were obtained. The results show that after 48 h of treatment the total pore volume decreases, attributed to reduction of pore interconnection, which was confirmed by the increase in electrical resistivity. Likewise, icorr, Rfilm, and Cdl results supported the passive film enhancement in both steels, which allows to decrease the oxygen on the metal surface, confirmed by σw. [ABSTRACT FROM AUTHOR]

In this study, experiments were carried out to assess the microbially influenced corrosion (MIC) risk in the context of the French high‐level radioactive waste disposal. The exposures were carried out at 80°C in different repository relevant conditions, including the presence of different cement‐grout mixtures as filling material. Biotic conditions with nutrient and nonsterile conditions with indigenous microbes added from Callovo Oxfordian clayey rock and without nutrients were considered. For biotic conditions, specific preparations of microbial inoculum were carried out from samples collected at Andra's Underground Research Laboratory and microorganisms from microbial culture collection centers. Corrosion kinetics were determined using traditional coupons and completed with real‐time corrosion sensors. Microbiological characterizations consisted of cultural approach, quantitative polymerase chain reaction, and next‐generation sequencing. The obtained results show no significant MIC and a reduced risk with the use of more alkaline filling material. [ABSTRACT FROM AUTHOR]

The long‐term disposal of nuclear waste in deep geological repositories requires safe containment for up to one million years. To understand how the waste will respond to the gradually evolving environment, researchers can perform sensitive experiments in the laboratory to replicate the repository conditions at specific time points. In Belgium, spent nuclear fuel will be housed within a carbon steel overpack, which is encased within a cement buffer, which may include a stainless steel liner (the "envelope"). The range of corrosion behaviors for carbon steel, and to a lesser extent, stainless steel, has been studied through hydrogen evolution, an end‐product of oxidation under repository conditions. Considerable time may be required for metallic surfaces to approach a steady hydrogen evolution and this is dependent upon the starting condition of the specimen surfaces. The use of nominally‐similar materials can result in significant variation in the reported corrosion rates. The presence of cements, which generate their own hydrogen and influence water chemistry as a function of time, add complexity to even simple experimental configurations that requires careful interpretation. [ABSTRACT FROM AUTHOR]

The proposed long‐term management plan for used nuclear fuel is to isolate it within a multiple‐barrier system underground in a deep geological repository (DGR). In the Canadian design, used fuel bundles will be sealed in copper‐coated carbon steel used fuel containers, encased in blocks of bentonite clay, emplaced approximately 500–800 m below ground, and surrounded by a bentonite gapfill material. A laboratory experimental campaign has been undertaken to demonstrate the integrity of the multiple‐barrier system. DGR‐relevant copper materials were embedded in bentonite clay, compacted to various densities, and sealed into a hermetic pressure vessel pressurized with demineralized water. Experiments explored the influence of bentonite compaction in the range of 1100–1600 kg/m3 on copper corrosion over durations of 1–18 months. Postexposure analysis of the copper coupons showed nonhomogeneous corrosion, with corrosion products composed of Cu2O, with some Cu2S. The average corrosion rates decreased as a function of time and increasing bentonite compaction density. In general, we observed that higher bentonite compaction density suppressed the corrosion of embedded copper. [ABSTRACT FROM AUTHOR]

Microscopic and spectroscopic analyses were conducted on steel/bentonite interface samples removed from four in situ experiments that were carried out in three underground research laboratories at different temperatures and under different hydraulic and geochemical conditions. The results provide valuable information about the corrosion processes occurring in high‐level radioactive waste repositories. Systematic patterns can be deduced from the results, irrespective of carbon steel grade, type of bentonite and its degree of compaction, geochemical environment or experimental setup. Thus, a clear dependence of the corrosion rates on temperature and exposure period, as well as on the availability of H2O and O2 provided by the surrounding bentonite buffer, is observed. Furthermore, Fe(II) ions released by corrosion interact with the structural Fe in the clay. Recent developments highlight the usefulness of reactive transport modelling in understanding the coupled corrosion and Fe–clay interaction processes. [ABSTRACT FROM AUTHOR]

In this paper, carbon steel corrosion rates from experiments performed in situ (performed in an underground rock laboratory) and ex situ (performed in a conventional laboratory) test methods in anaerobic saturated bentonite are compared. The results indicate that the long‐term corrosion rate follows a power law decay curve, with a higher initial rate and greater rate of decay at higher temperature. In compacted bentonite blocks, varying the density has no significant effect on the corrosion rate measured during in situ testing, whereas granular bentonite of an equal dry density leads to a higher corrosion rate. Precorrosion of test specimens in an aerated solution at room temperature has a negligible effect on the subsequent anaerobic corrosion rate when tested ex situ for durations up to 11.8 years. The main difference between in situ and ex situ tests is the formation of silicon‐rich corrosion products in the ex situ tests but not in the in situ tests. Despite these differences, the corrosion rates in both tests exhibit the same general temporal evolution and similar magnitudes, suggesting that the main steel degradation processes are maintained in both configurations. [ABSTRACT FROM AUTHOR]

In this study, short‐term experiments were carried out to assess the microbially influenced corrosion (MIC) risk in the context of the French high‐level radioactive waste disposal CIGEO (Centre Industriel de Stockage Géologique). The exposures were carried out in different representative media, including the presence of different cement‐grout mixtures as filling material. Nonsterile and biotic conditions with nutrients were considered. For biotic conditions, specific preparations of microbial inoculum were carried out from samples collected at ANDRA's Underground Research Laboratory and microorganisms from the library. Corrosion kinetics were determined using both traditional coupons and completed with real‐time electrical resistance sensors. Microbiological characterizations consisted of cultural approach, quantitative polymerase chain reaction, and next‐generation sequencing. The obtained results show no significant MIC, but a reduced risk was observed using more alkaline filling materials. [ABSTRACT FROM AUTHOR]

Copyright of Corrosion & Protection in Petrochemical Industry is the property of Corrosion & Protection in Petrochemical Industry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study provides two case studies involving carbon steel and 3%-Cr steel exposed to a CO2–H2S environment with a moderate scaling index. The carbon steel tubing show shows pitting and severe corrosion, whereas the 3% chromium steel tubes are undamaged. XRD results showed that the chromium-rich layer did not alter scaling on both tubes. Investigations using SEM and EDS reveal the formation of a dense and compact layer in the 3%-Cr steel, which serves to resist corrosion. In contrast, carbon steel has a porous structure and is easily detachable due to wall shear stress caused by slug movement. In 3%-Cr steel, the EDS analysis reveals a compact layer with a significant number of chromium, which is an indication of a Cr-rich iron oxide layer. Potentiodynamic polarization shows that the anodic curve is shifting, which means that the rate of corrosion is slowing down. This study shows that 3% Cr steel is a good choice for a mixed CO2–H2S environment with a high total dissolved solid (TDS). [ABSTRACT FROM AUTHOR]

Using gravimetric and electrochemical research methods, the corrosion-electrochemical behavior of carbon steel grade St3 in Kura river water has been. Gravimetric measurements were carried out under operating conditions of the Shemkir and Yenikend hydroelectric power stations for one year. Along with this, the ionic and bacteriological composition, as well as some physicochemical parameters of these waters were established. It revealed that St3 in the Kura water corrodes at a rate of (0.04÷0.05) g/m2•hour, which is characteristic of steel corrosion in fresh waters. In the atmosphere of hydraulic structures, steel corrodes at rather a low rate, i.e. (5÷6)10-3 g/m² hour. As a result of biochemical analysis, sulfate-reducing bacteria (SRB) were discovered in these waters, which are a dangerous organism that releases the corrosive substance of H2S. By taking the anodic and cathodic polarization curves, a quasi-stationary steel corrosion rate was established to be 0.06g/m² h [ABSTRACT FROM AUTHOR]