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The present research deals with the production and characterization of geopolymers prepared by mixing metakaolin with sodium silicate, sodium hydroxide solution and different amounts of electric arc furnace dust derived from the production of carbon steel, to be used by the construction industry. Specimens with compositions containing 90, 80, 70, 60 and 50 g of metakaolin and respectively 10, 20, 30, 40 and 50g of electric arc furnace dust powder were prepared. A blank composition containing metakaolin, sodium silicate, sodium hydroxide solution and free from electric arc furnace dust were also prepared for comparison. After production and hardening, all samples were characterized regarding compressive strength and water absorption. Hardened samples with compositions containing 10 and 30g of electric arc furnace dust were then submitted to a release test in order to evaluate the heavy metals elution. It has been observed that the addition of electric arc furnace dust worsens the pastes workability during their production in this way limiting the amount of electric arc furnace dust which may be added to the geopolymeric matrix. However, samples containing 90 g of metakaolin and 10 g of electric arc furnace dust still maintain fair compressive strength (about 27 MPa), low water absorption (about 28 %) and display limited elution of heavy metals. An additional thermal treatment of 1h at 700 °C, performed to induce sintering of the geopolymeric composites and therefore to reduce their porosity, did not lead to materials with improved performances. [ABSTRACT FROM AUTHOR]

Synthetic textiles such as polyesters are essential for daily life. However, large‐scale production generates large amounts of waste. This study introduces a new approach for valorising polyester textile waste (PTW) by transforming it into a catalyst for biodiesel production via pyrolysis. Specifically, a metal/carbon composite (PTW + steel slag [SS] composite—PSC) with enhanced catalytic properties was prepared by pyrolysing PTW with SS. The alkaline metals in SS facilitate the carbonisation of PTW via decarboxylation, resulting in a PSC rich in carbon, iron, and alkaline compounds. This composite featured mesopores that were larger than the micropores (MPs) typically found in PTW char. The use of porous material (silica) in thermally induced transesterification has been proven to be an efficient method for biodiesel production, achieving a yield of 97.20 wt.% in 1 min (faster than the 93.82 wt.% yields in 60 min observed from conventional alkali‐catalysed transesterification). However, the high reaction temperature (≥ 360°C) poses economic/technical challenges. To overcome this, PSC has been employed as a catalyst in thermally induced transesterification, leveraging its mesoporous structure and high alkaline content, particularly calcium oxide. The PSC achieved a biodiesel yield of 98.10 wt.% at a markedly lower reaction temperature of 120°C within 1 min. This performance was not attainable using silica or PTW char under similar conversion conditions. These findings highlight the potential of PSC produced through the pyrolysis of PTW and SS as effective catalysts for biodiesel production. This process is a promising strategy for converting waste into valuable resources and mitigating the environmental impacts associated with polyester waste. [ABSTRACT FROM AUTHOR]

In this study, the synthesis of a long-chain aliphatic amino compound and its sour corrosion inhibition properties were reported. Oleylamine was obtained through the reaction of 4-(Aminomethyl) pyridine with 1-chloro-octadecane. The identification and characterization of reaction products were carried out through Fourier transform infrared spectroscopy (FTIR) and gas chromatography/mass spectroscopy (GC-MS). Oleylamine was tested as a sour corrosion inhibitor for steels. Different concentrations of oleylamine (0, 5, 10, 25, and 100 ppm) in a sour saline electrolyte were analyzed. The dynamic anticorrosive behavior of oleylamine on carbon mild steel (AISI 1018) surfaces was evaluated using a laminar flow of 100 rpm and tested with potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) measurements. After electrochemical testing, the surface of the steel specimens that were used was characterized with Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The electrochemical results of the anticorrosive efficiency of oleylamine for steel showed an exponential behavior as a function of inhibitor concentration. At a concentration of 20 ppm of the inhibitor, the anticorrosive efficiency did not show any significant changes. However, at 100 ppm of the inhibitor, an efficiency of over 95% was achieved. After the electrochemical tests, the surface of the steel samples with the inhibitor revealed the formation of an inhibitor layer that prevented the corrosion of the steel. [ABSTRACT FROM AUTHOR]

Geothermal energy generation faces challenges in efficiency, partly due to restrictions on reinjection temperatures caused by scaling issues. Therefore, developing strategies to prevent scaling is critical. This study aims to simulate the scaling tendencies and corrosion effects of geothermal fluids on various construction materials used in scaling reactor/retention tank systems. A range of materials, including carbon steel, austenitic stainless steel, duplex stainless steel, two proprietary two-part epoxy coatings, and thermally sprayed aluminium (TSA), were tested in a simulated geothermal brine. Experiments were conducted in a laboratory vessel designed to replicate the wall shear stress conditions expected in a scaling reactor. The tests revealed varying scaling tendencies among the materials, with minimal corrosion observed. The dominant scale formed was calcium carbonate, consistent with geochemical modelling. The findings suggest that despite the high operating temperatures, the risk of corrosion remains low due to the brine's low chloride content, while the wettability of materials after immersion may serve as a useful indicator for selecting those that promote scaling. [ABSTRACT FROM AUTHOR]

Industrial boilers operate in extreme environments and are prone to degradation caused by high temperature oxidation, corrosion, and erosion. Protective coatings provide boiler components with protection to prolong their operation lifetime. Thus, a glass-ceramic coating has been developed using a slurry spray technique on carbon steel AS/NZS 3678 substrates. Microstructure, mechanical characteristics, and high temperature performance of the coating were investigated. The coating composed of chemically inert oxide ceramics dispersed in a glassy silicate binder matrix. The adhesion strength of the coating was 10.79 ± 0.86 MPa. Coating mass loss after abrasion test was 0.013 % of the tested specimen. The coating withstood at least 75 air quenched thermal shock cycles from 800 °C to the room temperature without any visible spallation and cracks. The coating mostly remained undamaged after cyclic oxidation at 800 °C for 10 cycles. However, minor iron oxide formation was observed, specifically, in relatively thin sections of the coating. The oxidation resistance of the boiler steel has been improved with the developed coating. The linear oxidation rate constant of the boiler steel has been statistically reduced from 6.90 × 10−4 mg cm−2 s−1 to 1.95 × 10−4 mg cm−2 s−1 for coated steel (p = 0.007). The developed slurry spray glass-ceramic coating is a potential candidate for boiler environments. [ABSTRACT FROM AUTHOR]

In this paper, an attempt was made to determine the load-bearing capacity of a bonded joint of galvanized steel elements with carbon fiber reinforced polymer (CFRP) fabric. This issue is extremely relevant to the use of bonded carbon fiber fabric as a mean of reinforcing hot-dip galvanized steel structures. This technique is used in engineering practice for both hot-rolled and cold-formed steel elements. In order to obtain the necessary parameters for modelling bonded joints of galvanised steel thin-walled elements, laboratory tests were carried out. In the first stage, four specimens made of 50 mm diameter steel cylinders bonded to 16 mm thick hot-dip galvanised steel sheet of S350 GD were subjected to the pull-off test. In this connection the SikaWrap 230C composite fabric embedded in SikaDur 330 adhesive layer was investigated. In the second stage, the axial tensile test of the bonded butt joint using the same materials was performed. In this stage, 10 hot-dip galvanised steel sheet samples of S350 GD and 16 mm thickness were tested. The discussion on the failure mechanism in the context of the bonding capacity of the composite joint was carried out. Moreover the advanced numerical model using the commercial FE program ABAQUS/Standard and the coupled Cohesive Zone Model was developed. The significant influence of the preparation method of steel element surface and the thickness of the adhesive layer on the failure mechanism of the joint and the value of the maximum failure force was shown. [ABSTRACT FROM AUTHOR]

This review summarizes the use of film-forming amines (FFAs) for corrosion protection in water/steam industrial circuits, focusing on carbon steel. It discusses industrial feedback on FFAs' benefits and challenges, alongside experimental methods for studying their inhibition and structural properties. Key research areas include FFAs' corrosion inhibition mechanisms, adsorption kinetics, and layer structures. The review also identifies knowledge gaps and suggests future research directions to deepen the understanding of FFAs. [ABSTRACT FROM AUTHOR]

This study investigates the efficacy of newly synthesized inhibitor with a dual function of corrosion inhibition and biocide for control of microbial influenced corrosion (MIC) in carbon steel API 5LX in the cooling tower water (CTW) environment. Four types of N-substituted tetrabromophthalic inhibitor (N-TBI) were synthesized, and the structural characterization was performed via proton nuclear magnetic resonance spectroscopy, thermogravimetric analysis and high-resolution mass spectrometry. These studies revealed the distinctive optical, thermal, and dielectric properties of the synthesized inhibitors. The corrosion inhibition efficiency has been evaluated by the weight loss (WL) analysis and electrochemical measurements (ECM) and biofilm assay. Biofilm assays and WL showed that inhibitor II exhibited the highest inhibition efficiency 74% and 79% respectively than others. Further ECM showed that the higher charge transfer resistance and the lower corrosion current, suggesting a protective film formed on the metal surface which was due to the adsorption of the N-TBI. Fourier transform infrared spectroscopy confirmed the adsorption of the N-TBI as C–O stretching and C–H bending with the Fe complex. X-ray diffractometer revealed that the presence of inhibitors in the corrosion product (Fe3O4, Fe2O3, FeH2O2, FeS) were highly reduced than the control system. Overall, this study highlighted the potential application of N-TBI with dual function of corrosion inhibition and biocide to control the MIC for carbon steel API 5LX used in the CTW environment. [ABSTRACT FROM AUTHOR]

The interaction of microalgae on the reinforced concrete with corrosion inhibitor is not well understood. Moreover, the inhibition role of microalgae on corrosion has been reported in recent years. In this study, the corrosion inhibition behavior of Q235 carbon steel (CS) due to the presence of Chlorella sp. and benzotriazole (BTA) in alkaline artificial seawater was investigated by means of weight loss, electrochemical measurements including open circuit potential, electrochemical impedance spectroscopy, and potentiodynamic polarization curves, and surface analysis including scanning electron microscopy, energy dispersion spectrometer, and X-ray photoelectron spectroscopy. The results of reduced corrosion rates in the algae-BTA system demonstrated that Chlorella sp. could facilitate the corrosion inhibition efficiency of BTA on the CS specimens. Moreover, polarization measurement showed the algae-BTA system had a mixed-type corrosion inhibition effect. The mechanisms of inhibition were proposed to be the precipitation of iron complexes such as Fe-BTA-EPS and Fe-BTA and iron compounds on the steel surface in the presence of the microalgae and BTA–. This study highlights the application of CS corrosion control by combining biological and chemical approaches that can be used for future research and practice, rather than purely chemical approaches. [ABSTRACT FROM AUTHOR]

The focus of this research is to examine the feasibility of using laser texturing as a method for surface preparation prior to thermal spraying. The experimental part includes the thermal spraying of a Stellite 6 coating by High Velocity Oxygen Fuel (HVOF) technology on laser-textured substrates. The thermal spraying of this coating was deposited both on conventional substrate material (low carbon steel) and on substrates that had been previously heat treated (nitrided steel). The properties of the coatings were analysed using scanning electron microscopy (SEM), optical microscopy (OM) and Raman spectroscopy. Adhesion was assessed through a tensile adhesion test. The results showed the usability of laser texturing in the case of carbon steel, which was comparable or even better than traditional grit blasting. For nitrided steel, the problem remains with the hardness and brittleness of the nitrided layer, which allows for the propagation of brittle cracks near the interface and thus reduces the adhesion strength. [ABSTRACT FROM AUTHOR]

In this investigation, the efficacy of PCA-GLU, a polymer obtained by copolymerizing citric acid and glutamic acid, as a corrosion inhibitor for carbon steel was investigated in a 3.5wt% NaCl solution. Electrochemical impedance spectroscopy (EIS) techniques and potentiodynamic polarization (PDP) measurements were used to evaluate the corrosion inhibition. The findings demonstrate that PCA-GLU has a 96.73% corrosion inhibition efficiency. Additionally, when the inhibitor concentration rises, the corrosion inhibition efficiency rises as well, reaching an ideal concentration of 400 mg/L. Furthermore, PCA-GLU can create an adsorption layer on the surface of Q235. This paper verifies the adsorption mechanism of PCA-GLU through molecular dynamics simulations of the system and quantum chemical calculations of corrosion inhibitors in solution. Ultimately, our research findings validate that PCA-GLU is an efficient corrosion inhibitor in safeguarding carbon steel against corrosion in marine environments. [ABSTRACT FROM AUTHOR]

In this present work, a damage-coupled cyclic plasticity model has been developed for more accurate ratcheting–fatigue life estimation under strain and stress controlled ratcheting. Ratcheting–fatigue damage behavior under uniaxial multistep strain-controlled ratcheting shows that the incremental mean ratcheting strain deteriorates the elastic slopes cycle by cycle, by means of ratcheting damage. Severe ratcheting strain accumulation rate has been observed in tertiary region under uniaxial stress controlled ratcheting. The proposed damage-coupled model has been constructed which incorporates both fatigue damage and damaging effect of the accumulated mean plastic strain. The proposed model incorporates a critical fatigue damage parameter which can predict effects of early fatigue crack nucleation due to combined ratcheting and fatigue damages. The performance of the proposed damage-coupled model has been investigated in the present study based on the critical fatigue damage parameter. The proposed model is calibrated on experimental data of SA333 Gr. 6 carbon steel and SA508 Gr. 3 steel. The proposed formulations have been applied in user material subroutine UMAT of finite element software, ABAQUS. The proposed model has been validated by comparing predicted ratcheting behavior with experiments for the two different steels. All the predicted number of cycles to failure are located within 0.5 times error band. The proposed damage-coupled model has demonstrated excellent capabilities of predicting ratcheting–fatigue life under cyclic loading with ratcheting damage. [ABSTRACT FROM AUTHOR]

Within the scoop of environmental sustainability, the elaboration of efficient inhibitors using biomaterials was investigated. Beginning with careful extraction of lignin from raw Alfa fibers. Following this, the study examined the synthesis and characterization of a new generation of corrosion inhibitors based on clays and lignin biopolymer. A comprehensive characterization of powder samples sepiolite-lignin (SP-L) and bentonite-lignin (BN-L) was executed by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) analysis and scanning electron microscopy (SEM) images. Electrochemical impedance spectroscopy and potentiodynamic polarization measurements were conducted on carbon steel immersed in 3%NaCl solution containing SP-L and BN-L composites, showing an interesting inhibition efficiency of 92.0% and 90.2%, respectively. The surface characterization of carbon steel, subsequent to immersion in 3%NaCl solution without and with SP-L or BN-L was conducted using XRD, FT-IR and SEM coupled with energy-dispersive X-ray spectroscopy analysis. Interestingly, the results of the blank sample revealed a deposition of corrosion products; mainly FeO(OH), Fe3O4 and iron carbonate (FeCO3), while SP-L and BN-L samples revealed an organic layer adsorbed onto the CS surface acting as a protective barrier. [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]

Surface carburized steels are extensively utilized in gears due to their exceptional properties. The quality of the carburized layer is crucial in enhancing the contact fatigue and wear resistance of the components. However, the conventional carburizing method takes a long time and induces a carbon emissions problem. In this study, the 18Cr2Ni4WA steel was double tempered (650 °C/4 h) after carburizing at 930 °C and 950 °C. The microstructural evolution, carbide precipitation, and mechanical properties of different carburized layers were analyzed. The results showed that increasing the carburizing temperature can control the microstructure of the carburized layer while reducing the carburizing time by over 60%. The high carbon content improves the strength of the carburized materials at 950 °C, and the inhibition of dislocation motion and grain boundary by the precipitation of more carbides ensures the stability of grain size, maintaining the strength of the materials. The carburized specimens at 950 °C showed an excellent combination of strength and plasticity in different carburized layers due to the variations in solid solution strengthening, dislocation strengthening, precipitation strengthening, and grain boundary strengthening induced by carbon atoms. This study holds significant reference for the advancement of modern steels carburized at high temperatures in a short time. [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 inhomogeneity present in the deformation and microstructure during the open die forging of large size ingot significantly influences the mechanical properties of the final part. This study aims to develop a microstructure-based finite element (FE) model and investigate the influence of deformation path on microstructure evolution during the upsetting process of large size ingot of a high strength steel. The difference in deformation path is achieved by modification in anvil shape such as flat, v shape, convex, and concave die. To achieve this goal, hot compression tests were carried out using the Gleeble 3800 thermomechanical simulator. Utilizing the acquired and corrected flow stress data, a material model and a microstructure model were established, and both formulated models were then integrated into the Forge NxT 3.2 finite element simulation software through the inclusion of a dedicated user subroutine. The predictions from the FE analysis were validated with experimental results on standard size hot compression specimens, which allowed for the accurate prediction of the dynamic recrystallized average grain size at the end of hot deformation. Afterwards, the validated FE model was scaled up to simulate the industrial upsetting process, making it possible to investigate the effect of deformation path on inhomogeneity of strain and microstructure evolution at the end of upsetting process for large sized forged ingots. An evaluative analysis of four die geometries, aimed at identifying the optimal die shape for minimizing inhomogeneity in strain and grain size across a large size forged ingot, was conducted. It was found that the convex die provokes the lowest deformation, while the concave die induces the highest deformation values at the center of the ingot. Utilizing the coefficient of variation as an indicator of heterogeneity, it was determined that the v-die and concave die resulted in a more consistent grain size distribution compared to the flat and convex dies. [ABSTRACT FROM AUTHOR]

This study focused on optimizing the hot forging process for AISI 1045 medium carbon steel ball joints, which is crucial for enhancing both their mechanical properties and production efficiency. Traditional hot forging processes often face challenges due to variations in flow stress and microstructural outcomes, which can result in a suboptimal product performance. To address these challenges, this research employed the Taguchi method in conjunction with a finite element (FE) simulation to identify the optimal forging parameters. The Arrhenius constitutive model, based on the Zener–Hollomon parameter, was applied to predict the flow stress with a high level of accuracy, achieving a coefficient of determination (R2) of 0.968 and an average absolute relative error (AARE) of 7.079%. An analysis of variance (ANOVA), a statistical innovation that partitions the total variation into components linked to key process factors, was utilized to determine the significance of these parameters. The ANOVA revealed that the billet temperature played a significant role in influencing the preforming force, finishing force, and mean stress, with a maximum impact of 62.30%, 59.50%, and 94.20% on the variation in the response variable, respectively. Additionally, the friction factor significantly affected the preforming and finishing forces, contributing 36.19% and 38.28%. The validation of the model through both simulations and practical experiments is a testament to the reliability of this research, demonstrating the accuracy of the model with minimal discrepancies in the forging forces and exhibiting errors of just 2.88% and 3.40%. Furthermore, microstructure modeling successfully predicted the key outcomes, such as the grain size and pearlite volume fraction, validating the effectiveness of the simulation in forecasting microstructural characteristics. [ABSTRACT FROM AUTHOR]

This paper presents the results of research from the renovation of functional parts of crane wheel surfaces. The aim of the research was to verify the possibilities of changing the chemical composition of the additive materials for submerged arc cladding, in order to increase the resistance of the wheel surfaces to wear. The base material of the crane wheel was heat-treated carbon steel for castings, mat. no. 1.0553. The renovation process was carried out on three equal wheels. Conventionally used additive material, the same one used for the interlayer and two covering layers, was used on one wheel. On two other wheels, newly increased tubular wires with a higher proportion of carbide-forming additives (Cr, Mo) were used for the carbide coating of two covering layers, in addition to their conventional additive material. Low-alloy additive material was applied to the newly elevated wires. The quality of the clads was assessed using non-destructive tests. Subsequently, microstructural analysis was carried out on the test samples taken from the renovated wheels, by means of light microscopy. On the cross cuttings, the course of hardness was evaluated using Vickers analysis. The resistance of functional surfaces to adhesion wear was evaluated based on weight losses measured using the AMSler experimental equipment. The results of the experiments showed an increase in the tribological resistance of the surfaces, specifically by 45% due to the newly developed wire C1 and by 18% due to wire B1, and it is therefore possible to recommend renovation. [ABSTRACT FROM AUTHOR]

The mechanism causing the dramatic intensification of the corrosion deterioration of carbon steel pipes in a crude oil storage facility has been investigated. This study considers a number of factors affecting corrosion in crude oil, such as the water content, the corrosivity of the aqueous phase, the kinetics of water–oil separation, the effect of dissolved oxygen, the effect of the crude oil quality, the degree of stagnancy inside of the pipes, the possible contribution of microbially induced corrosion (MIC) and the presence of deposits. The key root of the corrosion intensification was the separation of the water phase, supported by stagnancy, which eventually led to the formation of stable shallow pits surrounded by cathodic areas. [ABSTRACT FROM AUTHOR]

In the present study, directional and spatial variations in the mechanical properties are calculated in two nuclear-grade materials. In practice, multiple ASTM standard specimens are tested to measure mechanical properties of any material. The variations obtained in the properties during the tests are generally neglected assuming such variations are due to experimental uncertainties. However, such variations may indicate some degree of anisotropy and spatial inhomogeneity in the material due to component fabrication. In the present study, multiple miniaturized tensile specimens are tested. These specimen materials are taken across the thickness and at different geometrical locations in the two manufactured nuclear-grade components. The experimental load versus displacement data of all the specimens are then used to evaluate stress-strain data and cohesive zone parameters. These parameters are determined for each tested specimen separately to gather variations over the geometries of the components. Subsequently, TPB specimens are analyzed employing these parameters to calculate variations in fracture initiation toughness over the geometry. The key findings of the present work include higher strengths in circumferential direction in comparison to the longitudinal direction for SA333 Gr6 steel. A new equation is developed to correlate the material toughness with the fracture toughness with a proportionality constant of 2.7778 for low-alloy carbon steels. The study showed that directional and spatial variations in Jini are less pronounced in 20MnMoNi55 compared to SA333Gr6 materials. This finding is crucial for safety analyses in nuclear components and indicates that this methodology can be applied more widely across different materials. [ABSTRACT FROM AUTHOR]

In this study, synthesis and assessment of the corrosion inhibition of four new binary heterocyclic pyrimidinones on CS in 1.0 M hydrochloric acid solutions at various temperatures (30–50 °C) were investigated. The synthesized molecules were designed and synthesized through Suzuki coupling reaction, the products were identified as 5-((5-(3,4,5-trimethoxyphenyl)furan-2-yl)methylene)pyrimidine-2,4,6(1H,3H,5H)-trione (HM-1221), 2-thioxo-5-((5-(3,4,5-trimethoxyphenyl)furan-2-yl)methylene)dihydropyrimidine-4,6(1H,5H)-dione (HM-1222), 1,3-diethyl-2-thioxo-5-((5-(3,4,5-trimethoxyphenyl)furan-2-yl)methylene)dihydropyrimidine-4,6(1H,5H)-dione (HM-1223) and 1,3-dimethyl-5-((5-(3,4,5-trimethoxyphenyl)furan-2-yl)methylene)pyrimidine-2,4,6(1H,3H,5H)-trione (HM-1224). The experiments include weight loss measurements (WL), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). From the measurements, it can be shown that the inhibition efficiency (η) of these organic derivatives increases with increasing the doses of inhibitors. The highest η recorded from EIS technique were 89.3%, 90.0%, 92.9% and 89.7% at a concentration of 11 × 10−6 M and 298 K for HM-1221, HM-1222, HM-1223, and HM-1224, respectively. The adsorption of the considered derivatives fit to the Langmuir adsorption isotherm. Since the ΔGoads values were found to be between − 20.1 and − 26.1 kJ mol−1, the analyzed isotherm plots demonstrated that the adsorption process for these derivatives on CS surface is a mixed-type inhibitors. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), atomic force microscope (AFM) and Fourier- transform infrared spectroscopy (FTIR) were utilized to study the surface morphology, whereby, quantum chemical analysis can support the mechanism of inhibition. DFT data and experimental findings were found in consistent agreement. [ABSTRACT FROM AUTHOR]

Corrosion of carbon steel rebars in concrete structures significantly compromises their safety, reliability, and environmental performance. This work focuses on enhancing rebar corrosion resistance by repairing the defects of oxide scale. Here, sol-gel was employed as a carrier, by which Ce3+ and Ni2+ were transferred to the oxide scale defects based on the isoelectric point theory, and deposited at these defects with the pH variation as temperature. The repaired oxide scale showed enhanced uniform elemental distribution and improved electrochemical properties, maintaining integrity even under prolonged exposure to Cl−-rich environments. Notably, the impedance modulus at 0.01 Hz (|Z | 0.01Hz) of treated samples was six times higher than untreated ones, indicating superior performance against high electric fields. This strategy shows great potential for enhancing the durability of concrete structures. [ABSTRACT FROM AUTHOR]

In recent decades, in order to replace traditional synthetic polymer composites, engineering research has focused on the development of new alternatives such as green biocomposites constituted by an eco-sustainable matrix reinforced by natural fibers. Such innovative biocomposites are divided into two different typologies: random short fiber biocomposites characterized by low mechanical strength, used for non-structural applications such as covering panels, etc., and high-performance biocomposites reinforced by long fibers that can be used for semi-structural and structural applications by replacing traditional materials such as metal (carbon steel and aluminum) or synthetic composites such as fiberglass. The present research work focuses on the high-performance biocomposites reinforced by optimized sisal fibers. In detail, in order to contribute to the extension of their application under fatigue loading, a systematic experimental fatigue test campaign has been accomplished by considering four different lay-up configurations (unidirectional, cross-ply, angle-ply and quasi-isotropic) with volume fraction Vf = 70%. The results analysis found that such laminates exhibit good fatigue performance, with fatigue ratios close to 0.5 for unidirectional and angle-ply (±7.5°) laminates. However, by passing from isotropic to unidirectional lay-up, the fatigue strength increases significantly by about four times; higher increases are revealed in terms of fatigue life. In terms of damage, it has been observed that, thanks to the high quality of the proposed laminates, in any case, the fatigue failure involves the fiber failure, although secondary debonding and delamination can occur, especially in orthotropic and cross-ply lay-up. The comparison with classical synthetic composites and other similar biocomposite has shown that in terms of fatigue ratio, the examined biocomposites exhibit performance comparable with the biocomposites reinforced by the more expensive flax and with common fiberglass. Finally, appropriate models, that can be advantageously used at the design stage, have also been proposed to predict the fatigue behavior of the laminates analyzed. [ABSTRACT FROM AUTHOR]

Correct design of the sheet metal forming process requires knowledge of the friction phenomenon occurring in various areas of the drawpiece. Additionally, the friction at the drawbead is decisive to ensure that the sheet flows in the desired direction. This article presents the results of experimental tests enabling the determination of the coefficient of friction at the drawbead and using a specially designed tribometer. The test material was a DC04 carbon steel sheet. The tests were carried out for different orientations of the samples in relation to the sheet rolling direction, different drawbead heights, different lubrication conditions and different average roughnesses of the countersamples. According to the aim of this work, the Features Importance analysis, conducted using the Gradient-Boosted Regression Trees algorithm, was used to find the influence of several parameter features on the coefficient of friction. The advantage of gradient-boosted decision trees is their ability to analyze complex relationships in the data and protect against overfitting. Another advantage is that there is no need for prior data processing. According to the best of the authors' knowledge, the effectiveness of gradient-boosted decision trees in analyzing the friction occurring in the drawbead in sheet metal forming has not been previously studied. To improve the accuracy of the model, five MinLeafs were applied to the regression tree, together with 500 ensembles utilized for learning the previously learned nodes, noting that the MinLeaf indicates the minimum number of leaf node observations. The least-squares-boosting technique, often known as LSBoost, is used to train a group of regression trees. Features Importance analysis has shown that the friction conditions (dry friction of lubricated conditions) had the most significant influence on the coefficient of friction, at 56.98%, followed by the drawbead height, at 23.41%, and the sample width, at 11.95%. The average surface roughness of rollers and sample orientation have the smallest impact on the value of the coefficient of friction at 6.09% and 1.57%, respectively. The dispersion and deviation observed for the testing dataset from the experimental data indicate the model's ability to predict the values of the coefficient of friction at a coefficient of determination of R2 = 0.972 and a mean-squared error of MSE = 0.000048. It was qualitatively found that in order to ensure the optimal (the lowest) coefficient of friction, it is necessary to control the friction conditions (use of lubricant) and the drawbead height. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the composition of oxide films formed on SA106 Gr.B carbon steel in nitrite solutions at 35 °C for 1000 h. The product of the reduction of nitrite during the corrosion inhibition process was also examined. The X-ray photoelectron spectroscopy results revealed that a thin Fe3O4 film was formed and ammonium ions were adsorbed on the outermost surface of the oxide film. The presence of ammonium ions was also demonstrated by ion chromatography. These results indicate that nitrites are reduced to ammonium ions, which in turn promotes the formation of the protective Fe3O4 film. [ABSTRACT FROM AUTHOR]

This research focuses on cylindrical helical springs with circular cross-sections made from carbon steel (SH 0.82% C) and stainless steel (AISI 302). The transformation from a linear bar to a circular spiral involves numerous factors such as material mechanical behavior, stress–strain relationships and residual stresses. This research investigates the spring-back phenomenon, which affects the final diameter of helical springs post-manufacture, using analytical, experimental and numerical methods. An analytical model, derived from the mechanical bending process, was proposed to predict spring-back, and its accuracy was validated against experimental data. This study also employed finite element simulations to analyze elastic recovery, confirming the analytical predictions. Results indicated that the spring-back ratio k could be expressed as an exponential function of the spring index C (the ratio between the final diameter of the spring D2 and the diameter of the wire DW), with a maximum error of 4.80% for stainless steel and 3.62% for carbon steel. This study's findings provide valuable insights into optimizing the spring manufacturing process, enhancing the precision of spring diameter predictions, and potentially reducing production errors and material waste. [ABSTRACT FROM AUTHOR]

This study explores the potential of graphene oxide (GO) as an additive in waterborne polyurethane (WPU) resins to create eco-friendly coatings with enhanced anticorrosive properties. Traditionally, WPU's hydrophilic nature has limited its use in corrosion-resistant coatings. We investigate the impact of incorporating various GO concentrations (0.01, 0.1, and 1.3 wt%) and functionalizing GO with ethylenediamine (EDA) on the development of anticorrosive coatings for carbon steel. It was observed, by potentiodynamic polarization analysis in a 3.5% NaCl solution, that the low GO content in the WPU matrix significantly improved anticorrosion properties, with the 0.01 wt% GO-EDA formulation showing exceptional performance, high Ecorr (−117.82 mV), low icorr (3.70 × 10−9 A cm−2), and an inhibition corrosion efficiency (η) of 99.60%. Raman imaging mappings revealed that excessive GO content led to agglomeration, creating pathways for corrosive species. In UV/condensation tests, the 0.01 wt% GO-EDA coating exhibited the most promising results, with minimal corrosion products compared to pristine WPU. The large lateral dimensions of GO sheets and the cross-linking facilitated by EDA enhanced the interfacial properties and dispersion within the WPU matrix, resulting in superior barrier properties and anticorrosion performance. This advancement underscores the potential of GO-based coatings for environmentally friendly corrosion protection. [ABSTRACT FROM AUTHOR]

The development of pitting corrosion on L245 carbon steel in a culture medium solution containing sulfate-reducing bacteria (SRB) was investigated. The results showed that the occurrence of corrosion in L245 carbon steel is closely linked to the evolution of biofilm and product film. As the test duration extended, overall corrosion was inhibited. Simultaneously, bacteria beneath the film layer promoted the generation and development of pitting corrosion, and the aggregation of bacteria (colonies) led to the aggregation of pitting corrosion. [ABSTRACT FROM AUTHOR]

In search of new materials that would help to prevent microbiologically influenced corrosion (MIC), we have designed and synthetized six different copper and copper–silver nanoparticle–enzyme hybrids using a mild-conditions method carried out in water and r.t. Characterization analyses exhibited the presence of small crystalline nanoparticles with diameters from 2 to 20 nm. X-ray diffraction determined that the Cu hybrids were composed of different copper species, depending on the synthetic protocol used, while the Cu–Ag hybrids were mainly composed of copper and silver phosphate metallic species. Then, the bacterial viability of three MIC-relevant enrichments, sulfate-reducing bacteria (SRB), slime-forming bacteria (SFB), and acid-producing bacteria (APB), was studied in the presence of the bionanohybrids. The results demonstrated a notable effect of all bionanohybrids against SRB, one of the most prominent bacteria associated with MIC. In particular, Cu-2 and Cu–Ag-2 showed a reduction in bacterial cells of 94% and 98% after 48 h, respectively, at a concentration of 100 ppm. They also exhibited high efficiencies against SFB, with Cu–Ag-1 and Cu–Ag-2 hybrids being the best, with bacterial reduction percentages of 98% after 45 h of exposition at a concentration of 100 ppm. However, in the case of APB, the effect of the hybrids was lost due to the low pH level generated during the experiment. Finally, the capacity of Cu-2 and Cu–Ag-2 to inhibit the adhesion of SRB to the surface of carbon steel coupons was evaluated. Fluorescence imaging of the surface of the coupons at 24 h demonstrated that the presence of the hybrids inhibited the growth of SRB, obtaining a maximum reduction of 98% with Cu-2. Overall, the results of this study demonstrate that these novel nanomaterials have a wide-range antibacterial effect and may have a promising future in the prevention and treatment of MIC. [ABSTRACT FROM AUTHOR]

High-strength carbon steel bolts were fractured by the tension, shear, or combined failure mode in semirigid and flexible beam-to-column connections as observed from natural fire incidents and full-scale fire tests. This phenomenon is attributed to the temperature-sensitivity of quenching and tempering procedures on these bolts. However, provided that these bolts are replaced by stainless steel bolts in these connections, the connection performance of the latter can be better improved compared to that of the former. Accordingly, this paper documents an experimental investigation of low-carbon austenitic high-strength A4L-80 bolts after fire exposure to determine the temperature-based stress-strain curves. The residual properties of Young's modulus, yield and ultimate strengths, and ultimate strain obtained from the experimentally measured stress-strain curves were compared with those of base materials regarding A4L-80 and carbon steel bolts including Grade 8.8, 10.9, and 12.9. Considering the limitations of prediction accuracy of reduction models of base materials in the existing standards and design manuals, reduction models after fire exposure were proposed for five mechanical parameters (Young's modulus, yield and ultimate strengths, ultimate strain, and strain-hardening exponent in the Ramberg-Osgood model). In combination with the currently proposed reduction models, the temperature-dependent constituent model of A4L-80 was formulated using five mechanical parameters at ambient temperature. It is concluded that austenitic high-strength bolts after fire exposure are capable of providing a more pronounced enhancement to the fire resistance of semirigid connections than carbon steel bolts, and the formulated material model showed good consistency with stress-strain curves acquired from experimental tests. Finally, a finite element model (FEM) with this material model was established based on the previous experimental study of web angle cleat connections with A4L-80 after fire, according to which the moment-rotation curves obtained from FEM can correspond well to those done from tests in previous study. This confirms the further validation and prediction accuracy of the formulated material model. [ABSTRACT FROM AUTHOR]

Welding processes are widely used technologies in the industrial context for creating permanent connections between mechanical components. This popularity is due to their versatility, which arises from the numerous available process variants and the multiple advantages they offer compared to other joining techniques. In the manufacturing context, where devices often operate in extreme conditions, the quality of welds becomes a critical factor in ensuring the safety and reliability of the manufactured products. Furthermore, a sound joint requires careful compliance with the increasingly stringent design specifications demanded by customers who require industry-standard conformity in order to achieve defect-free, robust, and durable welds. To address these needs and to define the optimal roadmap for the investigated process condition, an experimental investigation was conducted on the submerged arc welding process. The experimental trials involved butt joints of ASTM A516 Gr.70 carbon steel plates with different thicknesses in a flat position, utilizing a U-shaped chamfer and a multi-pass welding technique. For each weldment, the effects of the main process parameters on the qualitative characteristics of the manufactured products were evaluated from a metallurgical perspective. This evaluation included an in-depth metallographic analysis of the heat-affected zone of the carbon steel joint and involved both the measurement of the dimensions of these areas as well as the amount of ferrite and pearlite that resulted as the phases observed in the final microstructure of the steel joint following its solidification. Furthermore, the joint quality was assessed with regard to mechanical strength through hardness measurements. By analysing the experimental data, the paper provides a valuable contribution for increasing the productivity of the investigated welding process, while simultaneously meeting the specified industrial quality requirements for the products made of medium-thickness carbon steels. [ABSTRACT FROM AUTHOR]

[Display omitted] • The self-healing and self-sensing coatings were developed based on pH stimuli. • The coating system shows excellent self-healing and self-sensing properties. • The cooperative effect of two inhibitors protects against steel corrosion. • The corrosion sensing ability is from the color change of Phen adsorbed on steel. Polyelectrolyte-encapsulated nanocontainers can effectively respond to changes of pH and thus control the on-demand release of corrosion inhibitors. A pH-responsive release system (Phen-Tpp@MTNs-PDDA) was developed based on the cationic polyelectrolyte poly dimethyl diallyl ammonium chloride (PDDA) encapsulated mesoporous TiO 2 nanocontainers (MTNs) loaded with 1,10-phenanthroline (Phen) and tripolyphosphate ions (Tpp) corrosion inhibitors. The epoxy coating (EP) embedded with Phen-Tpp@MTNs-PDDA (Phen-Tpp@MTNs-PDDA/EP) demonstrates superior self-healing properties and confers long-term protection on the metal substrate through the cooperative effect of Phen and Tpp. Simultaneously, this hybrid coating is endowed with corrosion sensing capability based on the color development originating from the interaction of Phen and carbon steel. This self-healing and corrosion-sensing multifunctional coating provides an effective strategy for the corrosion protection of metals. [ABSTRACT FROM AUTHOR]

The influence of austenitizing temperature and isothermal transition temperature on the mechanical properties and splitting characteristics of C70S6 were investigated. The maximum ultimate tensile strength and yield strength were 1032 and 625 MPa, respectively, when the lamellar spacing of sorbite was 0.195 μm. The greatest elongation was 17% when the size of the pearlite colony was 13 μm, which suggested an approach for enhancing the properties of pearlite steel at a low cost. The splitting property performed excellent when the proeutectoid ferrite content is 0.3%, the prior austenite grain is 38.9 μm, and the yield ratio is 0.57 currently. The connection between the process performance and the microstructure parameters was established, allowing process improvement to be guided accurately. Highlights: A functional model exploiting the potential mechanical properties of F + P forging steels C70S6 was proposed.The combined action of less proeutectoid F and larger PAG could obtain better splitting characteristics.The connection between the process performance and the microstructure parameters was established. [ABSTRACT FROM AUTHOR]

Currently, ultrasonic methods for assessing the fatigue lifetime of various structural materials are being actively developed. Many steel constructions are made by welding. The weld heat-affected zone is the weak point of the construction, as it is most susceptible to destruction. Therefore, it is actually important to search for acoustic parameters that uniquely characterize the structural damage accumulation in the heat-affected zone of a welded joint in order to predict failure. In this work, the specimens were made from the base metal and the welded joint's heat-affected zone. The specimens were subjected to uniaxial tension–compression under a symmetrical cycle in the region of low-cycle fatigue with control of the strain amplitude. The propagation bulk velocities of longitudinal, shear waves and subsurface longitudinal critically refracted (LCR) waves during cyclic loading were studied. The acoustic birefringence of shear waves was calculated, and a similar parameter was proposed for longitudinal and LCR waves. The dependence of the elastic modulus ratio on the cycle ratio was obtained. It was shown that the acoustic parameters change most intensively in the heat-affected zone. According to the data of the C33/C55 ratio changes measured through the ultrasonic method, a formula for calculating the remaining fatigue life in the heat-affected zone was proposed. [ABSTRACT FROM AUTHOR]

The results of the influence of a range of process liquids on the formation of strengthened nanocrystalline structures in the surface layers of steel samples with different carbon content during thermo-deformation treatment are presented. The liquids were mineral oil; mineral oil with active additives containing polymers; water; and an aqueous solution of mineral salts based on magnesium and calcium chlorides. The thickness and hardness of the nanocrystalline layer increased with increasing steel carbon content. The thickness and microhardness of Steel C45 are 230–240 μm and 8.6 GPa, respectively, when using mineral oil with AAP, 110–120 μm and 7.2 GPa, respectively, when using mineral oil alone, and for steel CT80 when using mineral oil, they are 180–200 μm and 9.1 GPa, respectively (C45 and CT80 refers to engineering steels). The process liquid is decomposed into its component chemical elements by the high temperatures and pressures in the contact zone of the tool with the treated surface. It also gives off active hydrogen, which diffuses into the surface layer of the metal and significantly affects its formation. It was established that the greatest thickness and hardness of the layers were obtained after processing pre-hydrogenated samples. The choice of process fluid is critical during thermo-deformation treatment. [ABSTRACT FROM AUTHOR]

Featured Application: Slender elliptical section tubes, with potential uses in aeronautical, aerospace or other mechanical contexts, have been printed in PLA and ABS. A safe-sided design method is presented, which was originally formulated for steel tubes and is now adapted and re-calibrated for use with 3D-printed polymer materials based on material properties determined from tensile and compressive testing. Local failure modes occurring in 3D-printed polymer elliptical section tubes in compression are investigated in the present study via a series of experiments, with the results compared to existing design proposals for slender steel analogues. Polylactic acid (PLA) and acrylonitrile butadiene styrene material specimens (ABS) have been printed in three orthogonal layering orientations, and tested in tension and compression to determine orthotropic material properties including strength, elastic modulus, failure strains and Poisson's ratio. Next, twenty-four 3D-printed elliptical cross-section tubes are tested in compression, with the polymer material, cross-sectional aspect ratio and tube wall thickness varied across the set. Results including the load-deflection behaviour, longitudinal strains, failure modes and ultimate loads are discussed. A design method formulated previously for slender steel elliptical hollow sections in compression is adapted for use with the 3D-printed polymer specimens. Upon appropriate rescaling of the design parameters, safe-sided and accurate predictions are provided by the design method for the compressive resistance of the PLA and ABS elliptical specimens, thus validating its application to cross-sections in materials other than carbon steel. [ABSTRACT FROM AUTHOR]

Two-month experiments were carried out with carbon steel electrodes buried in an artificial sand wetted at 50–55% of saturation with a 0.07 mol L−1 Na2SO4·10H2O solution. Various protection potentials (corrected from the ohmic drop) were applied from −0.60 to −1.13 V/Cu-CuSO4. In each case, the behavior of the electrode protected by cathodic polarization was compared with that of an unprotected electrode. The electrochemical study was performed using voltammetry, linear polarization resistance measurements, and EIS. Surface characterization of the coupons was carried out using optical microscopy and X-ray diffraction. First, cathodic protection was observed to induce a spreading of the electrolyte on the metal surface because of electrocapillary effects. The active area, or more precisely the wet area, of the electrode increased, leading to a decrease in soil electrolyte resistance Rs measured using EIS. This phenomenon was experimentally confirmed via visual observations of the surface of the coupons at the end of the experiments. Secondly, cathodic protection induced a passivation of the steel surface. The passive state persisted for 35 to 85 h after cathodic protection was stopped and could be studied during various periods of interruption of the protection. In each case, the OCP of the previously polarized coupons reached high values, actually 200–250 mV higher than those measured for the unprotected coupons, and was associated with high polarization resistance Rp values (~40 kΩ cm2). Depassivation of the metal finally occurred, a phenomenon revealed by simultaneous important drops of both OCP and Rp. [ABSTRACT FROM AUTHOR]

In the context of an increasing interest in the use of high-performance steels in the construction industry due to their superior mechanical properties, understanding the behaviour and assessing the performance of dissimilar welded connections becomes essential. When several steel grades are adopted for fabrication of the same dissipative element, dissimilar welded connections have a decisive importance regarding the seismic performance of the structural member. This paper presents the experimental results of monotonic and low-cycle fatigue (LCF) tests on dissimilar welded connections. The welded connections are designed to reproduce the loading state that occurs between the web and the flanges of dissipative links in an eccentrically braced frame, and represent combinations of S235 mild carbon steel, 1.4404 austenitic stainless steel, and S690 high-strength steel. The obtained experimental results provide a better understanding of the behaviour of dissimilar welded connections through the evaluation of their strength, ductility, and failure mechanisms, providing a basis for finite element (FE) models' calibration for further numerical simulations. This study contributes to the evaluation of the feasibility of connections between dissimilar steels in seismic-resistant steel structures. [ABSTRACT FROM AUTHOR]

Wear-resistant steel/carbon steel composite plates not only have the double performance advantages of high strength and wear resistance but can also reduce energy consumption and production costs. Based on a 50% reduction rate, the wear resistance of the BTW1/Q345 composite was studied at different annealing temperatures, and the dry friction and wear tests of the BTW1/Q345 composite at different annealing temperatures were carried out using RETC MFT-5000. By using the white-light interference three-dimensional surface profiler, scanning electron microscope (SEM), and backscattered electron diffraction (EBSD) technology, we carried out a detailed analysis of the macroscopic and microscopic morphology and wear mechanism of wear traces at different annealing temperatures. The effects of the annealing process on the thickness and composition of the wear layer were studied, and the causes of wear failure were analyzed based on the results of scanning electron microscopy. It was found that as the annealing temperature gradually increased, the particle size near the scratch of BTW1 in the wear-resistant layer of the composite plate became smaller. On this basis, the effects of different annealing temperatures on the friction and wear characteristics of the composite plate were further studied. At the annealing temperature of 860 ° C, the wear resistance of the material was the best. [ABSTRACT FROM AUTHOR]

Objective Sulfate-reducing bacteria (SRB) pose a threat to the safe operation of shale-gas-gathering pipelines. Therefore, it is essential to explore the role played by SRB in dedicated pipelines. Methods In this work, the corrosion behavior of SRB was investigated by organic carbon starvation immersion experiments combined with cell number monitoring, corrosion weight loss recordings, morphology and profile observations and electrochemical measurements. Results In experiments with sodium lactate content ranging from 0–3500 ppm, the corrosion rate and pitting depth were the highest at 350 ppm. Conclusions The results indicated that the reduction in carbon sources leads to bacterial starvation, which directly obtains electrons from metals and exacerbates corrosion. It is not appropriate to use the content of bacteria to determine the strength of bacterial corrosion. [ABSTRACT FROM AUTHOR]

The corrosion of metal not only produces serious economic losses and environmental pollution but also threatens equipment safety. Carbon dots (CDs) exhibit outstanding inhibition properties to availably retard the corrosion of metal. However, the present CDs-based corrosion inhibitors still fail to fully exert the environmentally friendly and low-cost merits of CDs. To address this issue, CD aggregates (CDAs) prepared by low-cost and eco-friendly CDs are developed as novel corrosion inhibitors for the first time, and their corrosion inhibition mechanism is disclosed. Specifically, CDAs with excellent long-term dispersion stability are synthesized by solvothermal treatment of CDs formed by citric acid and urea. CDAs at only 200 mg/L provide a corrosion inhibition effect of 90.38% for Q235 carbon steel in 1 mol/L HCl solution, approximately 1.53 times higher than that of CDs (59.21%). Moreover, the corrosion inhibition mechanism of CDAs is proposed through the analysis of adsorption isotherm, examination of corrosion morphologies, and theoretical calculations. That is, CDAs physically and chemically adsorb on the carbon steel surface, mainly hindering its anodic reaction, thus retarding the corrosion of carbon steel. This research firstly verifies the corrosion inhibition potential of green and low-cost CDAs and provides a novel strategy to promote the corrosion inhibition performance of CDs, promoting the progress of aggregate-based corrosion inhibitors.

Abstract In this study, synthesis and assessment of the corrosion inhibition of four new binary heterocyclic pyrimidinones on CS in 1.0 M hydrochloric acid solutions at various temperatures (30–50 °C) were investigated. The synthesized molecules were designed and synthesized through Suzuki coupling reaction, the products were identified as 5-((5-(3,4,5-trimethoxyphenyl)furan-2-yl)methylene)pyrimidine-2,4,6(1H,3H,5H)-trione (HM-1221), 2-thioxo-5-((5-(3,4,5-trimethoxyphenyl)furan-2-yl)methylene)dihydropyrimidine-4,6(1H,5H)-dione (HM-1222), 1,3-diethyl-2-thioxo-5-((5-(3,4,5-trimethoxyphenyl)furan-2-yl)methylene)dihydropyrimidine-4,6(1H,5H)-dione (HM-1223) and 1,3-dimethyl-5-((5-(3,4,5-trimethoxyphenyl)furan-2-yl)methylene)pyrimidine-2,4,6(1H,3H,5H)-trione (HM-1224). The experiments include weight loss measurements (WL), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). From the measurements, it can be shown that the inhibition efficiency (η) of these organic derivatives increases with increasing the doses of inhibitors. The highest η recorded from EIS technique were 89.3%, 90.0%, 92.9% and 89.7% at a concentration of 11 × 10−6 M and 298 K for HM-1221, HM-1222, HM-1223, and HM-1224, respectively. The adsorption of the considered derivatives fit to the Langmuir adsorption isotherm. Since the ΔG o ads values were found to be between − 20.1 and − 26.1 kJ mol−1, the analyzed isotherm plots demonstrated that the adsorption process for these derivatives on CS surface is a mixed-type inhibitors. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), atomic force microscope (AFM) and Fourier- transform infrared spectroscopy (FTIR) were utilized to study the surface morphology, whereby, quantum chemical analysis can support the mechanism of inhibition. DFT data and experimental findings were found in consistent agreement. Graphical Abstract

Acid mine drainage severely affects metallic materials due to the high acidity and oxidising capacity of these lixiviates. A study was carried out to evaluate the time evolution of the mechanical properties of AISI 1020 carbon steel and AW6060 aluminium in contact with acid mine drainage. Weight loss, fatigue and tensile strength were evaluated in two different scenarios, one involving erosion corrosion (dynamic scenario) and the other involving chemical corrosion only (static scenario). Over 80 days of exposure in a static scenario, weight loss is almost 2% for aluminium and 0.5% for steel, fatigue strength is reduced by 28% for steel and ultimate tensile strength is reduced by almost 5% for aluminium and by 2.5% for steel. In a dynamic scenario, the weight loss after 4 days of exposure is 30–35% for both materials, the fatigue strength is reduced by almost 50% for steel, the ultimate tensile strength is reduced by 33% for aluminium and by almost 5% for steel. Acid drainage causes an increase in brittleness and a decrease in stiffness of these materials, much more rapidly in a dynamic environment favoured by the effects of erosion corrosion.

This study is about making and figuring out what trimethoprim (TM), a popular corrosion inhibitor, is like and then using it as an inhibiting agent to stop corrosion in carbon steel in acid media (HCl solution) through adsorption. TM has also been known as the prevalent anti-corrosive agent. It can be added to a liquid or gas to slow the pace of a chemical reaction (in the case of a material – typically a metal or alloy – that corrodes when it encounters the fluid). Many antibiotic compounds, such as TM derivatives, diiron salt dihydrate, and diiron salt tetrahydrate, have active groups that can stop metal from corroding. Spectroscopic methods like XRD (X-ray difraction), FTIR (Fourier transform infrared spectroscopy), UV-visible (ultraviolet-visible spectroscopy), and TGA (thermogravimetric analysis) were used to study the TM drug. Similarly, the OCP (open circuit voltage) technique was introduced to assess the corrosion resistance and the density of current vs. voltage. Finally, this study revealed that TM drugs could be suggested for introduction as corrosion inhibitors due to their simple production and the fact that they have many active groups that exhibit the ability to coordinate with carbon steel. Our study revealed that changes in inhibitor concentrations, the solution's acidity, and the metal's surface area all contribute to adsorption.

The fracture behaviours of pearlite structures in several typical carbon steels were investigated by scanning electron microscopy (SEM). Microstructural analysis indicated that the fracture of pearlite is a mixed ductile-brittle fracture, and brittle fracture has cleavage fracture characteristics, which often occur inside the pearlite structure. The fracture surface can exhibit any orientation relationship with the ferrite/cementite interface plane in the pearlite structure. The two phases in the pearlite structure (ferrite (α-Fe) and cementite (θ-Fe3C)) are fine grains rather than single-crystal platelets. The cleavage fracture mechanism in any direction of pearlite structure occurs due to the fine grain substructure.

The corrosion features of 20# carbon steel, the base material of sour water stripper, in NH4Cl solution were examined in this research. The anatomical samples of the corroded parts were characterized by an X-ray diffractometer and other analytical tools. It was found to be a localized perforation caused by pitting, and the corrosion product was FeCl2. 20# steel was subjected to electrochemical testing using Tafel polarization and Electrochemical impedance spectroscopy. The studies showed that the 20# steel’s cathodic depolarization reaction rate speeds as density rises, and that the concentration polarization gets more marked as temperature rises. The corrosion rate of 20# steel is the fastest when temperature hits its highest point of 80°C, measuring 4.7142 mm/a. When density rose from 5 to 20%, corrosion rate grew from 1.6378 to 7.2430 mm/a.

Alanine hydrochloride was prepared from alanine, then its derivative was synthesized by amidation. The structure of the synthesized product was characterized by infrared and 1H nuclear magnetic resonance. The corrosion inhibition effect of alanine and alanine derivative on carbon steel at 30 ℃ in 0.5 mol/L sulfuric acid medium was studied by weight loss method, electrochemical method and scanning electron microscope. The results showed that alanine derivative had better corrosion inhibition than alanine due to the hydrophobic alkane long chain. The weight loss method and electrochemistry showed that the corrosion inhibition rate reached more than 90% at the alanine derivative dosage of 300 mg/L. The adsorption of corrosion inhibitor on carbon steel surface conformed to Langmuir adsorption model. Alanine derivative at low mass concentrations(50-100 mg/L) could inhibit the oxidation of anode metal,which was anode corrosion inhibitor. At higher mass concentrations(200-500 mg/L), the rate of hydrogen evolution reaction at the cathode and metal oxidation reaction at the anode was reduced at the same time, thus reducing the overall corrosion reaction rate, so alanine derivative was a mixed corrosion inhibitor.

Formation of Sulfate Reducing Bacteria (SRB) biofilm accelerates microbiologically influenced corrosion (MIC). The aim of this study was to investigate both the corrosivity of a marine SRB consortium on carbon steel coupons and its mitigation in the presence of ZnO. Metagenomics analysis revealed that Halodesulfovibrio (78.9%) was predominant and could be related to MIC. The analysis also showed a remarkable shift from a highly corrosive SRB consortium in the control bioreactors to a far less corrosive consortium when ZnO was added to the bioreactors. Further results indicated that the corrosion rate of the SRB consortium was 8.17 mpy on the carbon steel coupons. In the ZnO-treated bioreactors, the count of SRB and MIC in the carbon steel coupons simultaneously reduced. Moreover, Confocal Laser Scanning Microscopy and profilometry analysis determined that ZnO could significantly decrease the amount of biofilm and the corrosion rate. Electrochemical experiments revealed higher corrosion current density (icorr) and lower charge transfer resistance (Rct) in the control bioreactors relative to the ZnO-treated bioreactors. We introduce Halodesulfovibrio as a potentially important corrosive genus in a marine SRB consortium. Additionally, ZnO could be considered a proper candidate to control the corrosion induced by Halodesulfovibrio. [ABSTRACT FROM AUTHOR]

The power industry's low carbon transition is pivotal for achieving carbon reduction and sustainable development. This study uses the super epsilon-based measurement (Super-EBM) model and the Malmquist index to evaluate the power industry's low carbon transition efficiency using data from 30 provinces in China from 2010 to 2020, and utilizes the Tobit model to comprehensively analyze the factors affecting the low carbon transition of power industry. In addition, this paper examines the spatial differences in the power industry's low carbon transition efficiency as well as its distributional characteristics and dynamic evolutionary patterns. Conclusion is drawn as follows this paper analyzes the regional differences, spatial distribution characteristics and dynamic evolutionary trends of the power industry's low carbon transition. The main conclusions are as follows: (1) The power industry's low carbon transition efficiency in China shows an uptrend, with the western China region having the highest overall level of efficiency, greater fluctuations in the central China region, and more stability in the eastern China region, technological progress is a central factor in increasing total factor productivity, the efficiency of the power industry's low carbon transition is positively influenced by the electricity prices, and negatively influenced by the energy structure, environmental regulations and economic structure; (2) the Intraregional differences and hypervariable density are the main reasons sources of the overall differences in the efficiency of the power industry's low carbon transition; Intraregional differences in the eastern, central, and western China regions are decreasing year by year, but the efficiency of the power industry's low carbon transition in the western China region is still distributed in a multipolar way; (3) The dynamic evolutionary trends of the efficiency distribution of the low carbon transition in power industry is influenced by the type of spatial lag in the neighboring area. Where areas with low efficiency makes it difficult to achieve short-term leapfrog development, and areas with a cluster of high-efficiency provinces are prone to "Siphon Effect". The findings provide a theoretical basis for promoting the efficiency of the power industry's low carbon transition and coordinating the strategic adjustment of economic and environmental green development. [ABSTRACT FROM AUTHOR]