Carbon Steel Research Articles

Biomacromolecules as green corrosion inhibitors: a review based on mild steel corrosion in acidic media

Abstract Green corrosion inhibitors are produced from economical and renewable sources and concurrently offer high inhibition efficiency and very low negative effects on environment. Various naturally occurring biomacromolecules are employed as corrosion inhibitors for steels. In contrast to small molecule corrosion inhibitors, polymers possess superior film-forming abilities and multifunctional chemistries that have the potential to enhance protective barrier characteristics greatly. Moreover, the biomacromolecules have many sites of attachment which further enhance their inhibition ability. This featured article is dedicated to summarizing the inhibition performance of biomacromolecules to mitigate mild steel corrosion in acidic media. It began by describing the green corrosion inhibitors and the advantages of using biomacromolecules as inhibitors. All naturally occurring macromolecules such as such as carbohydrates, proteins, and nucleic acids, have been focused as inhibitors for mild steel in acidic media with their inhibition action. The factors affecting inhibition efficiency like temperature, inhibitor concentration, exposure time, etc. are also discussed. In the last, the synergistic effect of other ions with macromolecules in corrosion inhibition was also taken into consideration. This review offers insightful observations into the development of biomacromolecules as green corrosion inhibitors.

Оценка качества и механических свойств получаемых слоев металла из низкоуглеродистой стали методом WAAM с использованием дополнительной механической и ультразвуковой обработки

Introduction. Additive manufacturing is a technology that enables three-dimensional (3D) components to be printed layer by layer according to digital models. Completely different from traditional manufacturing methods such as casting, forging, and machining, additive manufacturing is a near net shape manufacturing process that can greatly enhance design freedom and reduce manufacturing runtime. The material processing challenges in Wire and Arc Additive Manufacturing (WAAM) are related to achieving performance metrics related to geometric, physical, and material properties. Tight tolerances and stringent surface integrity requirements cannot be achieved by utilizing stand-alone AM technologies. Therefore, WAAM parts typically require some post-processing to meet requirements related to surface finish, dimensional tolerances and mechanical properties. It is therefore not surprising that the integration of AM with post-processing technologies into single and multi-setup machining solutions, commonly referred to as hybrid AM, has become a very attractive proposition for industry. The purpose of the work is to evaluate the quality and mechanical properties of the resulting metal layers of mild steel by WAAM method using additional mechanical and ultrasonic processing. Research Methods. To conduct the experiments, a set of welding equipment was used — a single-phase inverter device KEMPPI Kempomat 1701, designed for welding with wire in shielding gases. A mixture of argon and carbon dioxide (80 % argon and 20 % CO2) was used as a shielding gas. SV-08G2S (0.8 C-2 Mg-Si) wire was used as the surfacing material. A plate made of steel St3 with overall dimensions 150×100×5 mm was used as a base for surfacing. The surface of the plate before surfacing was thoroughly cleaned from the layer of oxides, oil, rust and other contaminants. For this purpose mechanical cleaning of the surface was used with BOSCH abrasive wheel with a diameter of 125 mm diameter and a grit size of 120. Before surfacing the surface of the product was degreased with white spirit. The gas flow rate was set at 8 dm3/min. To select the optimal wire feed rate and volt-ampere characteristic, surfacing was performed at each adjustment step of wire feed rate, and voltage. Mechanical statistical tensile tests, chemical composition analysis and metallographic studies were also performed. Results and Discussion. Gas porosity is a typical defect that occurs during the WAAM process and should be eliminated because it adversely affects the mechanical properties. Initially, gas porosity leads to a reduction in the mechanical strength of the part due to damage from microcrack formation. In addition, it often causes the surfaced layer to have worse fatigue properties due to the spatial distribution of different shape and size structures. In our experiments we found that a wire feed speed range of 5–6 m/min is optimal. Increasing the flow rate of shielding gas in the range of 8–14 l/min allows reducing porosity in the surfaced metal to almost zero. The mechanical properties of the surfaced beads show that the average value of yield strength after machining is higher than that of unprocessed specimens. The data obtained from these experiments are in good agreement with those reported in the literature. The presented results can be used in real WAAM technological processes.

Synthesis of O,F Co-Modified g-C3N4 for Photocatalytic H2 Evolution Activity Improvement and Corrosion Protection

Herein, we report the rational synthesis of porous g-C3N4 co-modified with oxygen (O) and fluorine (F) for the first time. Incorporating colloidal SiO2 during thermal polymerization introduces lattice oxygen, forming C–O bonds, while post-treatment with NH4·HF2 establishes C–F bonds. The dual incorporation of O and F elements extends visible light absorption and effectively promotes the separation and transport of photoexcited charge carriers. Consequently, the co-modified g-C3N4 (O,F-g-C3N4) achieves a 13.2-fold increase in H2 evolution rate compared to pristine g-C3N4. This synthesized O,F-g-C3N4 is then dispersed in waterborne polyurethane (WPU) to create an anti-corrosive coating for Q235 carbon steel substrates. Water resistance, mechanical property, and electrochemical characterization analyses reveal that the O,F-g-C3N4/WPU composite coating exhibits remarkable corrosion resistance with a high protection efficiency of 90.23%. This work offers a straightforward approach for developing highly efficient g-C3N4-based photocatalysts and corrosion-resistant coatings.

Dual anaerobic reactor model to study biofilm and microbiologically influenced corrosion interactions on carbon steel

Continual challenges due to microbial corrosion are faced by the maritime, offshore renewable and energy sectors. Understanding the biofilm and microbiologically influenced corrosion interaction is hindered by the lack of robust and reproducible physical models that reflect operating environments. A novel dual anaerobic biofilm reactor, using a complex microbial consortium sampled from marine littoral sediment, allowed the electrochemical performance of UNS G10180 carbon steel to be studied simultaneously in anaerobic abiotic and biotic artificial seawater. Critically, DNA extraction and 16S rRNA amplicon sequencing demonstrated the principal biofilm activity was due to electroactive bacteria, specifically sulfate-reducing and iron-reducing bacteria.

The effect of welding time on the tensile load capacity of dissimilar-metal stainless steel-carbon steel TIG-Spot welded joint

This study examines the influence of welding time on the tensile load capacity of spot TIG welds using stainless steel and low carbon steel plates (100 mm × 30 mm × 0.8 mm) as per AWS D8.9 standards. A constant welding current of 90 A was applied, with 2-, 3-, 4-, and 5-seconds welding times. Tensile properties, microstructure, and hardness were analyzed using a universal tensile machine, an optical microscope, a scanning electron microscope, and a Vickers hardness tester. Results show that the tensile load capacity increases with welding time, peaking at 4 seconds (≈4300 N), before dropping significantly at 5 seconds (≈4000 N) due to overheating, which weakens the joint. The findings highlight the critical role of optimizing welding time to maximize joint strength while preserving the material's microstructure. Overextended welding times compromise performance, emphasizing the balance required for achieving durable welds.

Corrosion inhibition effects of celery (Apium graveolens) seeds extract on carbon steel in acid medium

The present study highlights the inhibition performance of celery seeds (CS) extract on carbon steel immersed in 1M HCl, using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization methods. This extract is selected due to biodegradable, renewable, and foremost aspect, is safe towards both the human being and environment. The studied inhibitor was easily extracted by using a simple aqueous extraction procedure. The experimental results show that the investigated inhibitor can effectively retard the corrosion process that occurs to carbon steel in hydrochloric acid solution. Electrochemical impedance spectroscopy (EIS) spectra showed that inhibition efficiency increases with the increasing of (CS) extract concentration. Among the studied inhibitor showed maximum inhibition efficiency of 96,86% at 250 ppm. Polarization curves indicate that (CS) extract acted as mixed type of inhibitors with a predominant effect on the anodic reactions. Basic calculations for the adsorption studies were also carried out. The adsorption of the extract onto carbon steel surface followed the Langmuir adsorption isotherm.

Investigation of the Effect of Copper Nanoparticle Deposition on Low-Carbon Steel using Physical Vapor Deposition for Solar Cooling Application

The use of nanomaterials in solar cooling applications has gained significant attention in recent years. This study aimed to increase thermal conductivity by depositing copper nanoparticles (Cu-NP) on low-carbon steel using thermal evaporation and a physical vapor deposition (PVD) method. Low-carbon steel was selected as the substrate due to its wide use in thermal applications and strong absorption properties. The presence of Cu-NP on the surface was analysed using XRD and thermal characteristics of the thin layer were determined using Thermal Constant Analyzer (TCA) and Transient Plane Source (TPS) measurements. Results showed that the copper nanoparticle coating sample on the carbon steel substrate had better heat emission and absorption compared to the carbon steel alone. It also shows some improvement of around 1% in the thermal conductivity results. This study demonstrates the potential of using Cu-NP deposited on low-carbon steel as a promising material for solar thermal/cooling applications.

Advancing a Comprehensive Model for Carbon Steel Corrosion in Weak Acids: Validation Using Valeric and Acetic Acids

Acidic corrosion in industrial environments represents a serious threat that requires an active prevention and management strategy. In this context, weak acids can create a severe corrosion environment for metallic surfaces, sometimes exceeding the severity observed in strongly acidic solutions under similar conditions. While most of the research efforts of the last decades in the field of the predictive modeling of acidic corrosion have been focused on the specific case of sweet corrosion caused by carbonic acid, the goal of this work is to describe and validate a predictive model to be used as a more transversal tool for acidic corrosion. The model, called the Tafel–Piontelli model, leverages Tafel law to mechanistically describe the electrochemical behavior of carbon steel in acidic aqueous environments. Two different acids, acetic and valeric, were used to experimentally evaluate the performance of the model in weakly acidic solutions, varying the pH and the temperature conditions. Potentiodynamic polarization tests and mass loss tests were performed, allowing us to assess the kinetic parameters (the Tafel slope and the exchange current density of the cathodic and anodic reactions) and corrosion rates of the corrosion process. The promising results suggest that the Tafel–Piontelli model is able to adapt to different scenarios and its intrinsically theoretical nature allows us to extend its predictions outside the range of experimental conditions used to validate it.

Comparative study on corrosion characteristics of conductive concrete in red soil environment.

In order to solve the corrosion problem of grounding materials in highly corrosive red soil environments, conductive concrete was proposed as a new type of grounding material. The corrosion resistance of conductive concrete was tested and compared to select a suitable preparation scheme with excellent corrosion resistance. A series of conductive concrete samples were made using different conductive materials such as graphite, stainless steel fiber (SSF), and ordinary silicate concrete. Common grounding metals include Q235 steel and galvanized steel, embedded in red soil, conventional concrete, and conductive concrete. The open circuit potential, dynamic potential polarization, and electrochemical impedance spectroscopy of these metals were measured and analyzed. The open-circuit potential of metal electrodes in red soil is lower than that in concrete, and the potential of specimens with conductive phase is higher than that of the ordinary concrete, show that the corrosion sensitivity of metals in conductive concrete is greatly reduced, the corrosion potential is the lowest and the corrosion current is the highest in red soil, the capacitance arc radius in red soil is very small, indicating poor corrosion resistance of grounding metals in a red soil environment. All these indexs indicate that using conductive concrete as grounding material can effectively slow down the corrosion of grounding materials in red soil. Compared with stainless steel based conductive concrete, graphite based conductive concrete provides better protection for the grounding metal wrapped around it. As the content of conductive phase materials increases, the corrosion tendency and corrosion rate of conductive concrete decrease. Compared with Q235 carbon steel, galvanized steel exhibits excellent corrosion resistance in conductive concrete. Therefore, it is recommended to use galvanized steel conductive concrete as the grounding material for power systems in red soil environments.

Preliminary Evaluation of Nickel Silicide (NiSi12-wt%) Laser Cladding for Enhancing Microhardness and Corrosion Resistance of S355 Steel

S355 construction steel, a commonly used mild steel due to its exceptional strength, is prone to environmental degradation, especially pitting corrosion in highly corrosive marine environments. To address this vulnerability, applying a surface layer of nickel silicide (NiSi) cladding on such components could offer a solution, given that NiSi-based alloys are known for their high corrosion resistance and exceptional mechanical properties. Thus, the present study has investigated the corrosion resistance and microhardness of the NiSi12-wt% cladding deposited onto substrates of S355 steel using laser metal deposition. An accelerated ASTM G48 corrosion test and a Vickers microhardness test were conducted in a solution of 6% ferric chloride (FeCl3) solution at room and elevated temperatures to represent marine environments, with uncladded sheet substrates exposed to the same test environments as a reference. All exposed S355 steel samples, with and without cladding, underwent microhardness testing and were characterized using light optical microscopy (LOM) and low-voltage field emission scanning electron microscopy (LVFESEM). The findings indicate that the NiSi12-wt% cladding significantly enhances the corrosion resistance and mechanical properties of the S355 steel samples, showcasing its potential for use in marine and industrial environments where corrosion and mechanical wear are expected.

An epoxy resin-based superhydrophobic coating incorporating pH-responsive functional multiwall carbon nanotubes assembled L-proline for corrosion protection

Purpose This paper aims to improve the corrosion resistance of AH36 carbon steel, an epoxy resin (EP)-based superhydrophobic coating was prepared on the surface of AH36 carbon steel. Design/methodology/approach The hydroxylated multi-walled carbon nanotubes were used as nanocontainers, and the corrosion inhibitor L-proline was loaded by negative pressure method and then modified it with 3-aminopropyltriethoxysilane and 3-mercaptopropyltrimethoxysilane, got functionalized hydroxy carbon nanotubes (KH-CNTs@LP). The KH-CNTs@LP was mixed with the EP, and the KH-CNTs@LP/EP superhydrophobic coating was successfully prepared on the surface of the AH36 carbon steel matrix by spraying. Findings The results showed that the water contact angle of the KH-CNTs@LP/EP superhydrophobic coating is 155.2° and the rolling angle is 5°. The KH-CNTs@LP/EP superhydrophobic coating had a good corrosion resistance in the pH = 4 corrosion environment, |Z|0.01 Hz was 7.21 × 107 Ω·cm2. Originality/value The KH-CNTs@LP/EP superhydrophobic coating is pH-responsive and releases L-proline, which increased the impedance of the coating and can effectively improve the protection efficiency of the coating on the metal. The active protection is provided by loaded L-proline inhibitor from KH-CNTs@LP, whereas the passive protection is achieved through the water rejection of superhydrophobic surfaces.

Wear Behaviour of Friction Surfaced Al-Ni and Al-SiC Coatings over Mild Steel

Abstract The friction surfacing (FS) method offers solid-state deposition of both identical and distinct coatings while avoiding a number of the issues that encompass the traditional fusion coating process. This study investigates FS for depositing aluminium based metal matrix composites (MMCs) onto AISI1018 mild steel substrates. The Al-2Si-15SiC and Al7075-15Ni MMC consumables used for the FS process were fabricated via stir casting. The FS process, optimized at 1200 rpm for Al-SiC and 1500 rpm for Al-Ni, resulted in refined microstructures and enhanced properties. Scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) of the coating reveals surface with equiaxed and fine grains. The development of Al3Ni intermetallic compounds at the coating's interface strengthens the bond by allowing the substrate and coating material to diffuse into each other. An excellent bonding strength of 147 MPa and 142 MPa is observed for the Al7075-15Ni and Al-2Si-15SiC coating deposits, respectively. In comparison to MMC consumable rods, the FS composite coating delivers 80–85% reduction in grain size and enhances hardness. Vickers microhardness tests showed substantial hardness increases, with Al-Ni coatings reaching 183 HV. Wear tests indicated that Al-Ni coatings outperformed Al-SiC coatings and the steel substrate, exhibiting lower wear rates and friction coefficients. This research underscores FS's effectiveness in improving the properties of aluminium MMC coatings on mild steel, with Al-Ni coatings showing exceptional wear resistance and bond strength for industrial applications.

Significant Improvement in Mild Steel Mechanical Properties with Cu-Fe-Ti Alloy Coatings

This research examines the mechanical properties of mild steel using the electrodeposition of ternary Cu-Fe-Ti alloys with varying Ti compositions at room temperature. The coating process maintained constant pH, current density, deposition time, and temperature. X-ray diffraction analysis revealed single-phase compositions with a face-centered cubic (fcc) structure for all electrodeposited samples. The crystallite sizes ranged from 14-17 nm. The lattice parameters of the Cu-Fe-Ti alloys strongly depended on the Ti concentration. Scanning electron microscopy images showed smoother surfaces with increasing Ti content. Energy-dispersive X-ray spectroscopy confirmed the presence of Cu, Fe, and Ti in the coatings. The Vicker hardness increased from 255 HV to 444 HV. With more Ti in solution, the Cu-Fe-Ti alloy coating thickness on mild steel decreased from 63 μm to 25 μm, and the surfaces became smoother. Thus, the improved mechanical properties correlate with Ti concentration, lattice parameter, crystallite size, and coating thickness. Enhanced mechanical properties of mild steel with Cu-Fe-Ti alloy coatings offer potential for improved durability and performance in radiation therapy equipment and medical imaging devices.

Evaluation of galvanic corrosion in mild steel, 309S and 409M alloy combinations for marine environment applications

Abstract The objective of this study is to simulate galvanic corrosion in 409M, 309S (weld filler)-& MS joints couples during in light of field applications and to compare with the corrosion rates of the individual grades. Metals undergo corrosion when exposed to outdoor environments. But the rate of corrosion gets accelerated when the metals are connected to form a galvanic couple and are exposed to marine environments. One such galvanic system being used in coastal aggressive environments like marine applications can be combinations of Mild steel (MS)- 409M (Ferritic Stainless Steel) system welded using& 309S (Austenitic Stainless Steel) filler. The electrochemical tests which include measurement of voltage/current w.r.t time, cyclic potentiodynamic polarization studies and electrochemical impedance measurements using 5% NaCl solution were designed in order to assess how these alloys behave (i) individually and (ii) in galvanically-coupled states. Visual observations, determination of corrosion rates, microstructural inspections and Scanning Electro Microscopy (SEM) analysis were carried out as a part of corrosion evaluation method. The results indicated that the galvanic coupling of dissimilar metals significantly accelerates the corrosion rate of the less noble metal, particularly in the MS-309S couple where the difference in their corrosion potentials between the two alloys is as high as 450 mV. The corrosion rate of MS coupled with 309S increased to 0.277 mm/yr, which is approximately 6.9 times more compared to the MS-MS couple. From the above study, it was found that the MS samples experienced higher corrosion rates when coupled with 309S, followed by MS in MS-409M system. The comparison was done with respect to MS-MS system. The test data shall be used to compare the relative corrosion resistances of (i) MS - MS (ii) MS - 409M (iii) 409M – 409M (iv) 309S - 409M (v) 309S - MS and (vi) 309S – 309S. This is required to understand the relative corrosion resistances of alloys during field application and to arrive at a suitable solution for maximizing its service life.

Corrosion Inhibition of Mild Steel by Plumeria rubra Flower Extract: Electrochemical and Computational Study

AbstractThe corrosion inhibition efficiency of Plumeria rubra flower extract (PRFE) on 5LX70 mild steel in 4% NaCl aqueous medium was studied by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and density functional theory (DFT). The PRFE was analyzed by FTIR for the confirmation of functional groups in the extract molecules. EIS and PDP methods indicated that the corrosion inhibition was increased with an increase in the concentration of inhibitor, with a surface area coverage of 90.12%. Polarization results revealed that PRFE is a mixed‐type inhibitor. A maximum corrosion inhibition of 90.98% was achieved at 120 ppm of extract concentration. Quantum chemical parameters of the inhibitor molecules were calculated using the DFT method to ascertain the relation between the parameters and inhibition efficiency. Molecular descriptors like HOMO, LUMO, energy gap, absolute electronegativity, electrostatic surface potential, and so on, were determined, and found that the inhibitor molecules favorably formed a protective layer on the metal surface. The Mulliken charge analysis of the constituent atoms of selected PRFE molecules further supported in identifying the active sites for binding with the mild steel surface. Experimental results have confirmed that PRFE is a good corrosion inhibitor for mild steel which was further affirmed by the computational study.

Synthesis investigation and exploring of new tetraglycidyl bisurea bisphenyl S polyepoxide as an excellent corrosion inhibitory resin for mild steel in 1M HCl environment: Comprehensive approaches

This work reports the synthesis of new epoxy resin namely tetraglycidyl bisurea bisphenyl S (TGBUBS). TGBUBS was characterized through using nuclear magnetic resonance (1H NMR and 13C NMR) and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). TGBUBS was investigated as an excellent organic inhibitor for protecting the mild steel from corrosion in 1M HCl solution at different concentrations. Anticorrosion protection behaviors were evaluated and more discussed including different techniques such as potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and contact angle (CA) measurements. The obtained results showed that the TGBUBS exhibited inhibition efficiencies at lower concentration are 93.19 % (PDP) and 91.21 % (EIS), respectively. Further, PDP measurements indicated that the TGBUBS acted as a mixed-type inhibitor in 1M HCl solution. Furthermore, SEM and EDS analysis showed a significant reduction in the corrosion on the mild steel surface when the inhibitory epoxy resin was present compared to the blank solution (1M HCl). The effectiveness and interactions of the new epoxy resin on the mild steel surface were also predicted using DFT calculations and molecular dynamics (MD) simulations. The theoretical approaches are in agreement with the experiment results.

Dichloromethane -methanol fraction of Mahonia nepalensis containing Berberine, Jatrorrhizine, and tetrahydroberberine as corrosion inhibitor for mild steel

A potentially superior alternative source of environmentally acceptable corrosion inhibitors for metallic materials is plant extracts. This study reports on the use of compounds separated from Mahonia nepalensis (MN) bark extract as an environmentally friendly corrosion inhibitor for mild steel (MS) in 1 M H2SO4. The organic layer was separated from MN bark extracts and then Berberine, Jatrorrhizine, and Tetrahydroberberine were identified and quantified by Liquid column mass spectroscopy (LC-MS) in dichloromethane (DCM) −Methanol fraction of Mahonia nepalensis. The DCM − Methanol fraction of extract was characterized by Ultra violet − visible spectroscopy (UV–Vis) and Fourier Transform Infrared (FTIR). The DCM-Methanol fractions in 1 M H2SO4 were applied to study corrosion inhibition of MS by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed above 91 % inhibition efficiency (IE) for DCM-Methanol fraction containing 2.12 ppm berberine, jatrorrhizine, and tetrahydroberberine at room temperature indicating that it is an effective and cheap candidate for the corrosion prevention of MS in industry. The potentiodynamic polarization demonstrated a reduction in current density without affecting the reaction mechanism but reduced the hydrogen reduction indicated by suppression in cathodic current. Based on polarization curves and open circuit potential, it exhibited mixed inhibitory behavior. Similarly, EIS analysis revealed a drop in double-layer capacitance accompanied by an increase in charge transfer resistance. EIS and a scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDX) ascertain the adsorption of inhibitor molecules forming a protective layer on the MS surface.

Eco-friendly corrosion inhibition of steel using phenolic compounds from Cynara syriaca

This study evaluates the corrosion inhibition performance of the n-butanol (n-BuOH) fraction derived from Cynara syriaca on mild steel in acidic environments. The n-BuOH fraction achieved up to 94 % inhibition at 500 ppm, as assessed through gravimetric analysis, potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). Key phenolic compounds, including kaempferol, naringenin, myricetin, chlorogenic acid, and quercetin, were identified by UPLC-MS/MS. These compounds form stable flavonoid-metal complexes, as confirmed by UV–Vis spectroscopy. FT-IR and SEM-EDS analyses revealed the formation of protective coatings and interactions with the steel surface. Polarization curves indicate that the n-BuOH fraction acts as a mixed-type inhibitor, predominantly affecting the anodic reaction. The inhibition efficiency decreased from 93.89 % to 73.43 % with increasing temperatures. Thermodynamic analysis showed an increase in activation energy (Ea = 58.20 kJ/ mol) and a positive ΔH value of 56.17 kJ/mol, which can be attributed to the increased thickness of the double layer, enhancing the activation energy of the corrosion process. A Gibbs free energy (ΔG0ads) value of −25.48 kJ/mol confirms that the adsorption process is spontaneous and involves both physisorption and chemisorption. pKa analysis identified specific adsorption sites. This research underscores the potential of the n-BuOH fraction as a novel, eco-friendly corrosion inhibitor, offering valuable insights for sustainable corrosion control strategies.

Temporal denoising and deep feature learning for enhanced defect detection in thermography using stacked denoising convolution autoencoder

Thermal wave imaging uses the temporal temperature distribution over the object’s surface for subsurface analysis. However, the noise generated during experimentation corrupts this temporal history and hampers the detection of defect signatures. As denoising of the temporal thermal history enhances the defect detectability, this study offers a stacked denoising convolution autoencoder (SDCAE) in frequency-modulated thermal wave imaging with one-dimensional convolution layers to reduce noise in temporal thermal evolution and train high-level features resulting in improved defect signs. Experimental results on mild steel and carbon fiber reinforced polymer specimens with different sizes of defects at various depths demonstrate that integrating temporal denoising and deep feature learning techniques into a single novel framework significantly improved defect detectability. In addition, defect signal-to-noise ratios of the denoised thermal data and latent space of the proposed model compared to conventional autoencoder and dimensionality reduction techniques recommend the superiority of the proposed method.

A sustainable approach for the corrosion control of mild steel using Cocous nucifera gum: An electrochemical investigation

The study of corrosion inhibition on mild steel (MS) in an acid medium (1 M HCl) solution was performed using a crude extract of Cocousnucifera gum (CNG). Cocousnucifera develops gum exudates on its palm, the exudate process occurs mainly after some physical or microbiological injuries and is formed on the fruit of the palm. The gum was utilized to study the corrosion inhibition of MS by electrochemical and surface studies. The characterization of the crude gum was done by Fourier transform infrared spectroscopy (FT-IR) which revealed the presence of several active components (aromatic and oxygen-containing functional groups) in its structure. The electrochemical studies resulted in the maximum inhibition efficiency value of 75.64 % at the highest inhibitor concentration of 4000 ppm at 308 K. It was inferred that both the anodic dissolution of the metal and cathodic hydrogen evolution were effectively decreased in the presence of Cocous nucifera gum extract, revealing that inhibitor is of mixed type. From the adsorption studies, it was found that the best fit with R2 ∼ 0.9 followed Langmuir adsorption isotherm indicating the monolayer adsorption of the inhibitor on the metal surface. Gibb’s free energy of adsorption values was found <−20 kJ/mol, a characteristic of predominant physical adsorption. To support the electrochemical data SEM (scanning electron microscopy), AFM (Atomic force microscopy), and X-ray diffraction analysis were performed and these are in good agreement.