Carbon Steel Surface Research Articles

Syzygium polyanthum (Wight) Walp. leaf extract as a sustainable corrosion inhibitor for carbon steel in hydrochloric acidic environment

This study focuses on an investigation of the corrosion inhibition behavior of Syzygium polyanthum (Wight) Walp. leaf extract (SPWE) of carbon steel in 1.0 M hydrochloric acid medium. Electrochemical methods demonstrated a corrosion inhibition efficiency of 94.65 ± 0.94 % when 2000 ppm extract is added to the corrosive solution. Furthermore, surface analysis results indicated that with the absence of an inhibitor, the steel surface suffered severe corrosion, while the corrosion density was slow, and a film was observed on the surface after applying the SPWE into a corrosive environment. The film formed by the chemical and physical adsorption of compounds such as polyphenol, flavonoid, alkaloid, and tannin onto the carbon steel surface has been qualitatively and quantitatively analyzed in this study. Notably, increased immersion time and reaction temperature led to significant desorption of molecules, reflecting characteristic of physical adsorption. However, the corrosion inhibition efficiency of SPWE remained effective, particularly within the temperature range of 25–35 °C. Therefore, this study provides an efficient inhibitor for carbon steel corrosion in 1.0 M hydrochloric acidic environment that could be possibly added to the corrosion inhibitor system.

Effect of thermal etching and oxidation on in situ characterisation of grain growth in carbon steel

This paper presents the results from a recent investigation into the impact of thermal etching and oxidation on grain growth across the surface and bulk of carbon steel during heat treatment. The study used in situ high temperature Scanning Electron Microscopy imaging, facilitated by a novel heat stage, to capture microstructural changes during heat treatments between 800 and 920 °C. The key observations made using this surface imaging included oxidation, the formation and development of thermal etching, and grain boundary movement. In situ data were further supported by ex situ compositional and optical microstructural data obtained by first sectioning the bulk material. Comparison between the results highlighted a significant discrepancy between the surface and bulk grain growth of the specimens during heat treatment at all temperatures. Further investigation concluded that the combination of thermal etching and oxidation lead to the retardation of grain growth on the surface of the carbon steel, but that grain growth in the bulk specimen appeared to be unaffected. The mechanism that causes the grain retardation is not dissimilar to that of Zenner pinning, where in this case oxide particles pin the newly exposed etched grain boundaries. Hence, oxidation formation within the boundaries decreases the energy of the overall system resulting in movement of the grain boundary becoming less energetically favourable. It is anticipated that these findings will be used to improve understanding of the surface effects that occur during the heat treatment of carbon steel in a vacuum environment.

Assessing the anti-corrosive properties of 2,6-bis-furan-2ylmethylene-cyclohexanone as a carbon steel inhibitor in 0.5M HCl solution

This study investigated the effectiveness of 2, 6-bis-furan-2ylmethylene-cyclohexanone as a corrosion inhibitor for carbon steel in a 0.5 M HCl solution through a combination of experimental and theoretical methodologies. Firstly, the study employs weight loss analysis, revealing that the presence of 0.10 ppm of the inhibitor leads to a significant inhibition efficiency (IE) of 93.40 % against corrosion in acidic conditions. Polarization studies further elucidate the inhibitor's role, indicating its function as a cathodic inhibitor and its influence on the corrosion kinetics of carbon steel. Moreover, alternating current impedance spectra are analysed to gain insights into the electrical behaviour of the protective film formed by the inhibitor and its consequent impact on the corrosion resistance of carbon steel. The composition of this protective film, comprising both carbon steel and 2, 6-bis-furan-2ylmethylene-cyclohexanone was confirmed using advanced imaging techniques such as scanning electron microscopy (SEM) and atomic force microscopy (AFM). In addition to experimental investigation, a theoretical approach was also employed using Density Functional Theory (DFT) to predict the behaviour of the inhibitor at the molecular level on the surface of carbon steel. This theoretical framework facilitates a deeper understanding of the interactions between inhibitor molecules and the carbon steel surface, offered insights into the mechanisms underlying the corrosion inhibition process. By utilizing quantum chemical calculations, the study aims to elucidate the inhibitory properties of 2,6-bis-furan-2ylmethylene-cyclohexanone against corrosion of carbon steel, thereby contributing to the development of effective corrosion inhibition strategies.

One-pot synthesis of N'-(thiophen-2-ylmethylene)isonicotinohydrazide Schiff-base as a corrosion inhibitor for C-steel in 1 M HCl: Theoretical, electrochemical, adsorption and spectroscopic inspections

Although carbon steel (CS) is an essential component utilized in many industries, it regrettably corrodes when exposed to acidic conditions. Schiff bases have recently become more concerned with the corrosion prevention of CS. Hydrazides and the related compounds shown to be effective inhibitors of CS corrosion in acids. These compounds are commonly employed as origins or intermediates to several key molecules in the synthesis of organic compounds, and they are highly sought after due to their wide range of biological and therapeutic applications. They have anti-bacterial, anti-malarial, anti-fungal, and anticancer properties, as well as corrosion protection. Hence, the inhibitory effectiveness of a new synthesized (E)-N'-(thiophen-2-ylmethylene) isonicotinohydrazide (TMNH) Schiff-base for the corrosion of CS in 1 M HCl was explored. The structure of TMNH was validated by FT-IR and 1H NMR spectroscopy. A number of chemical, spectral, and electrochemical techniques such as potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), and mass loss (ML) have been used to evaluate its anticorrosion power. PDP measurements showed that it is a mixed-type inhibitor. In addition, EIS measurements showed that Rct increased sharply from 37 without the corrosion inhibitor to 589 Ω cm-2 in the presence of 1 mM TMNH and from PDP scans, the corresponding icorr decreased dramatically from 0.6158 to 0.0314 μA cm-2. ML tests have proven their effectiveness, achieving an inhibitory efficiency of 95.3 %. Adsorption studies were also conducted to determine the nature of the corrosion retardation mechanism. The TMNH inhibitor was spontaneously chemically/physically adsorbed onto the CS surface following the Langmuir isotherm. Statistical calculations were also applied to verify the accuracy of the experimental results. The Monte Carlo model showed that the inhibitory molecules adsorbed flat on only one side, increasing the chances of adsorption.

An Evaluation of the Corrosion Inhibition Performance of Chitosan Modified by Quaternary Ammonium Salt for Carbon Steel in Stone Processing Wastewater.

Chitosan was used as the raw material. A quaternization reaction was carried out between 2,3-epoxypropyltrimethylammonium chloride and water-soluble chitosan to prepare quaternary ammonium salt water-soluble chitosan (QWSC), and its corrosion inhibition performance against the corrosion of carbon steel in stone processing wastewater was evaluated. The corrosion inhibition efficiencies of QWSC on carbon steel in stone processing wastewater were investigated through weight loss, as well as electrochemical and surface morphology characterization techniques. The results show that QWSC has superior corrosion inhibition performance for A3 carbon steel. When an amount of 60 mL·L-1 is added, the corrosion inhibition efficiency can reach 59.51%. Electrochemical research has shown that a QWSC inhibitor is a mixed-type corrosion inhibitor. The inhibition mechanisms of the QWSC inhibitor revealed that the positive charge on the surface of carbon steel in stone wastewater was conducive to the adsorption of Cl- in the medium, which produced an excessive negative charge on the metal's surface. At the same time, the quaternary ammonium cation and amino cation formed in QWSC in stone processing wastewater can be physically absorbed on the surface of A3 carbon steel, forming a thin-film inhibitor to prevent metal corrosion.

Verbena officinalis (VO) leaf extract as an anti-corrosion inhibitor for carbon steel in acidic environment

In the present work, Verbena Officinalis (VO) leaf extract was used as potential corrosion inhibitor for the corrosion of carbon steel (CS) in 0.5 M H2SO4 medium. Further, the corrosion inhibiting nature of VO leaf extract towards the CS was evaluated using mass loss (ML), potentiodynamic polarization (PDP), electrical impedance spectroscopy (EIS) and surface morphological analyses using atomic force microscope (AFM) and X-ray photoelectron spectroscopy (XPS) techniques. Calculation of activation energy Ea∗\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\left( {{\ ext{E}}_{{\ ext{a}}}^{*} } \\right)$$\\end{document} using Arrhenius equation shows the increase in activation energy when adding the VO leaf extract in 0.5 M H2SO4 medium and the maximum activation energy (Ea∗\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{E}}_{{\ ext{a}}}^{*}$$\\end{document} = 49.9 kJ mol−1) was observed for 1000 mg L−1 VO leaf extract in acid medium. The negative free energy values suggested the spontaneous and the stability of the adsorbed layer of VO leaf extract on the CS surface. Using EIS measurements, high percent inhibitory effectiveness of 91.1% for 1000 ppm solutions was achieved. With an increase in VO leaf extract dose, the double layer capacitance (Cdl) values fall while the values of charge transfer (Rct) increase. This showed that a protective layer of VO leaf extract on CS surface was formed. The polarization curves showed that the VO leaf extract acts as a mixed-type inhibitor. It is discovered that the adsorption of VO leaf extract molecules adhering to the CS surface followed the Langmuir isotherm. The anti-corrosion action of VO leaf extract is fully demonstrated by some surface techniques.

Augmentation of Polymer-FeCO3 Microlayers on Carbon Steel for Enhanced Corrosion Protection in Hydrodynamic CO2 Corrosion Environments.

Carbon dioxide (CO2) internal corrosion of carbon steel pipelines is a significant challenge and is typically managed by adding corrosion inhibitors. In certain operational conditions, a natural protective layer of iron carbonate (FeCO3) can form on the internal walls of the pipeline, offering inhibition efficiency comparable to that of standard surfactant inhibitors. However, incomplete coverage of the FeCO3 layer on carbon steel can sometimes trigger localized corrosion. Our previous research demonstrated that poly(allylamine hydrochloride) (PAH) can work synergistically with FeCO3 when the corrosion product partially covers X65 carbon steel surfaces in an aqueous CO2 corrosion environment. In this study, we utilize rotating cylinder electrode (RCE) tests along with electrochemical measurements to investigate the FeCO3-PAH hybrid structure in a dynamic environment. We characterize the general and localized corrosion behavior as well as the surface properties of both naturally formed FeCO3 and FeCO3-PAH hybrid layers using interferometry and focused ion beam scanning electron microscopy.

Analysis of a film-forming amine response in impedance spectra

In this study, a detailed analysis of the dielectric response of a film-forming amine (1,3 N-oleyl propanediamine (OLDA)) in impedance spectra is presented, addressing both “bulk” OLDA and adsorbed OLDA layer on a carbon steel surface. The dielectric response of the “bulk” OLDA in the absence of electrolyte over an extensive temperature range (-150 °C to 50 °C) was explored by broadband dielectric spectroscopy (BDS). Subsequently, the response of the OLDA adsorbed layer on the steel surface was analysed by electrochemical impedance spectroscopy (EIS), for various immersion times (2 min to100 min) and temperatures (25 °C to 75 °C) in an aqueous NaCl solution.Impedance spectra (BDS and EIS), interpreted through the complex conductivity formalism, showed a resistive behaviour in the mid-frequency range and a capacitive behaviour at higher frequencies. The high frequency capacitive response in EIS spectra was shown to contain contributions from the OLDA layer and from the electrochemical double layer, as well. The temperature dependency of the OLDA conductivity was found to be similar to the temperature dependency of the electrolyte resistance, suggesting that the electrolyte (water and ions) crossed the OLDA layer to reach the steel surface. The presence of gauche defects in the OLDA alkyl chain, revealed by polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) analyses, may be a contributing factor to the disorder in the adsorbed layer, facilitating electrolyte infiltration.

Alumina-based ceramic coatings obtained by the SHS process for high temperature corrosion and wear protection of steel tubulars

Ceramic coatings have much potential for steel tubulars' protection against high temperature corrosion of gases and liquids, often containing abrasive solid particles, and to enhance their integrity in severe power generation, mineral and oil & gas production environments. Combining self-propagating high-temperature synthesis (SHS) with high-speed centrifugal process, alumina-based coatings were produced onto the inner surface of tubulars for these applications. According to the developed SHS batch formulation and the designed centrifugal device and process, well-consolidated composite ceramic layers with a thickness of 1.5–3 mm have been obtained. The developed SHS process does not create hazardous gases, and it takes ∼30 s for the ceramic phase formation. A high-level compaction due to centrifugal forces and a liquid phase sintering approach provided a dense gradient ceramic structure formed by oxide grains cemented by a glassy phase and bonded with a steel substrate through a thin iron layer. The coatings were successfully produced onto the inner surface of carbon and stainless steels’ tubes of up to 12 ft-lengths and standard dimensions from 2 to 3/8″ to 7.5” OD. The coatings were tested, for the first time, in wear and high-temperature corrosive environments, e.g., in steam–H2S–CO2 gases and molten salts, with encouraging results due to high contents of Al2O3 and some other oxides and consolidated ceramic structure. They can be recommended for applications in high-temperature (900 °C and greater) corrosive environments and erosive flows.

Inhibition of carbon steel corrosion caused by Pseudomonas aeruginosa biofilms using the eco-friendly ε-Polylysine antimicrobial peptide

This study evaluated the effect of the ε-Polylysine (E-PL) antimicrobial peptide on the corrosion behavior of P. aeruginosa attached to carbon steel surfaces. The results showed that E-PL exhibited good antibacterial and antibiofilm activity, further effectively inhibited the corrosion behavior of P. aeruginosa by biofilm thickness, surface morphology, corrosion product, EIS and molecular biology method. In addition, the transcriptome and qPCR data showed that E-PL significantly downregulated the expression of key genes in flagella, quorum sensing, biofilm formation, and phenazines for resisting microbiologically influenced corrosion. This study has theoretical significance for evaluating the corrosion of marine equipment.

Seaweed extract as green corrosion inhibitor for carbon steel in hydrochloric acid solution

This study aimed to investigate the corrosion inhibition effect of seaweed extract abbreviated as SAE on carbon steel (CS) in 1.0 mol/L hydrochloric acid (HCl) solution. The functional groups in SAE were characterized using Fourier transform infrared (FTIR) spectroscopy. The corrosion inhibition effect of SAE on CS was determined through weight loss experiments, electrochemical tests, and scanning electron microscopy (SEM). Additionally, the composition of the corroded CS surface after immersion in SAE solution was measured through X-ray photoelectron spectroscopy (XPS) analysis. The results indicate that SAE achieves a corrosion inhibition efficiency of 95.0 % for CS in 1.0 mol/L HCl. Furthermore, SAE was identified as a mixed-type inhibitor. The adsorption of SAE on the CS surface follows the Langmuir adsorption isotherm model. UV–visible spectroscopy (UV–vis) studies confirmed that the corrosion inhibition of CS was achieved through the formation of CS-SAE phytoconstituents complex. Moreover, Molecular dynamics simulations (MS) and quantum chemical (QC) calculations were utilized to predict the adsorption properties of several major SAE components and the chemical parameters associated with inhibitory efficiency. This work offers insightful information for developing and applying eco-friendly CI for acid pickling or rust removal from CS.

Effect of linking group on the corrosion inhibition performance of triazine-based cationic Gemini surfactants: Experimental and theoretical investigation

Three kinds of triazine-based cationic Gemini surfactants (TCGSII, TCGSIV and TCGSVI) with different lengths of the linking group were synthesized and characterized by FT-IR, 1H NMR and ESI-MS. The surface activity test showed that the surface activity of the surfactants decreased with the increase in the length of the linking group from 2 to 6. At the same concentration, the corrosion inhibition rate decreased with the increase in the length of the linking group, decreasing in the following order: TCGSⅡ > TCGSⅣ > TCGSⅥ. The corrosion inhibition effect of 0.2 mM TCGSⅡ reaches 98.03 %. The adsorption of the synthesized surfactants on the surface of carbon steel conforms to the Langmuir adsorption isotherm, and included physisorption and chemisorption on the metal surface. Quantum chemical calculations and molecular dynamics simulations verify this conclusion.

Facile route for processing natural polymers for the formulation of new low-cost hydrophobic protective hybrid coatings for carbon steel in petroleum industry

This research helps with the creation, assessment, and characterization of a new hybrid protective coating for carbon steel alloy in acid conditions. The findings of this study will be useful for both chemical and petrochemical companies as well as scientists. This study aims to protect C-steel in acid pickling solution 1.0M HCl and formulate new hydrophobic protective hybrid organic–inorganic coatings from biopolymers chitosan and plant resin guar gum. Eight coating samples of chitosan in the absence and the presence of guar gum, silica and two heterocyclic compounds are prepared at feasible operational conditions using hot melt method. The aiding additives improved compatibility between coating constituents as confirmed by using different methods of analysis. This new processing approach has addressed the problems of using chitosan in corrosion control such as solubility in acid media and low mechanical strength. Coating samples of chitosan and its composites with the heterocyclic compounds (2-Hydrazinyl-6-methyl-4, 5-dihydro pyrimidine-4-on) or (2-Hydrazinyl-6-phenyl-4, 5-dihydro pyrimidine-4-on) are potent biocides. Coating shifts corrosion potential of carbon steel by 30 mV to more noble direction relative to the active potential 520 mV of bare carbon steel surface. Impedance and polarization measurements indicate that coating samples protect metal surface as mixed-type inhibitor by adsorption mechanism. There is a good agreement between percentages protection %P of coating calculated using the values of charge transfer resistance, Rct, and corrosion current density, icorr. All %P values are above 99% for all coating samples. Guar gum plant resin increases gloss of the coating film. Silica fills the pores in the polymeric film and increases the stuffiness of the polymeric coating film by modifying the particle size. All coated samples have high contact angle ranging from 150° to 165° indicating low wettability and high hydrophobicity of coating film on the metal surface.

Evaluation of green corrosion inhibitors of chitosan oligosaccharide derivatives for CO2 corrosion inhibition on 20# carbon steel

Two chitosan oligosaccharide derivatives, VCOS and GCOS, were synthesized and explored as corrosion inhibitors, the synergistic inhibition effect of KI and VCOS was also studied. Their structures were elucidated using Fourier Transform Infrared Spectroscopy and Nuclear Magnetic Resonance. The inhibition efficacy of VCOS+KI and GCOS on 20# steel within an 80℃, 3 wt% NaCl, CO2-saturated solution system was investigated employing various techniques, including gravimetric measurement, electrochemical analysis, Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), and molecular dynamics simulations. The results reveal that the inhibition efficiency of VCOS is relatively low when it acts alone. When VCOS and KI are combined, they have a good synergistic effect, and the synergistic parameter is the highest at 6.209. In the weight loss experiment, the corrosion inhibition efficiency increased with the concentration of the corrosion inhibitor. The inhibition rates of VCOS+KI and GCOS were 90.5 % and 90.2 %, respectively. The adsorption on 20# steel conformed to the Langmuir isotherm adsorption equation. The measurement results of SEM, Energy Dispersive Spectroscopy, and AFM show that VCOS+KI and GCOS adsorbed on the surface of carbon steel to form a dense inhibitor film, which effectively protected the metal substrate. According to the polarization test results, both VCOS+KI and GCOS are mixed-type inhibitors primarily exhibiting anodic inhibition, with inhibition efficiencies reaching 98.9 % and 95.1 %, respectively. Electrochemical impedance spectroscopy tests showed that with increasing inhibitor concentration and immersion time, Rct increased and Cdl decreased, resulting in a gradual increase in inhibition efficiency and the formation of a dense and stable inhibitor film. The results indicate that VCOS+KI and GCOS are non-toxic, water-soluble, and environmentally friendly inhibitors with good anti-corrosion performance.

Electrodeposition of myristate based superhydrophobic coatings on steel with enhanced corrosion resistance and self-cleaning property

In recent decades, superhydrophobic (SHP) coatings have gained significant attention because of their versatile applications. Superhydrophobic coating is considered as a promising solution to combat corrosion and biofouling issues encountered by steel components in various industries. Using a one-step electrodeposition technique, a superhydrophobic coating with strong corrosion resistance and anti-biofouling property was fabricated on carbon steel in this work. With a water contact angle (WCA) of 170.3 ± 4.2° and a sliding angle (SA) of ∼1°, the wettability of the surface was optimized by varying the electrodeposition potential and deposition time. The as-developed superhydrophobic carbon steel surfaces were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), laser Raman spectroscopy (LRS), Energy dispersive X-ray (EDS) spectroscopy and X-ray diffraction (XRD). Employing field emission scanning electron microscopy (FESEM), the morphology of the superhydrophobic coatings was examined. Potentiodynamic polarization (PDP) technique was used to study the anti-corrosion property of SHP coating and bare sample in 3.5 wt% NaCl solution. The superhydrophobic coating was found to exhibit 99 % corrosion inhibition efficiency. In addition, the biofouling resistance of the coating was evaluated in both gram-negative and gram-positive bacterial cultures and compared with the uncoated sample. Total viability count (TVC) for the SHP coated samples was 5 orders less as compared to the uncoated sample exposed to gram-negative bacterial culture. Similarly, 4 orders reduction in TVC was estimated for the SHP coated sample as compared to the uncoated sample in gram-positive bacterial culture. The impact of superhydrophobic coating on the corrosion performance and biofouling properties of carbon steel was investigated along with the self-cleaning property and robustness of the coating.

Evaluation of Corrosion Inhibition of Low-Carbon Steel Using Chamomile Plant Extract

The investigation focused on elucidating the corrosion inhibition mechanism of chamomile extract, serving as an environmentally sustainable inhibitor, across various concentrations (0.2, 0.4, 0.6, 0.8, 1.0 w/v %) applied to carbon steel immersed in a 0.6 M NaCl variations in temperature affect the solution. (303, 313, 323, 333 K). The analytical approach involved Assessment of weight reduction metrics complemented by sophisticated techniques, Scanning Electron Microscopy (SEM), Gas Chromatography-Mass Spectrometry (GC-MS), and Energy Dispersive X-ray Spectroscopy (EDS) were used to analyze the carbon steel surface with and without the extract. The principal aim was to conduct a detailed examination of the development of a layer of adsorption layer. The obtained results consistently validated a positive correlation between inhibition efficiency and extract concentration. SEM imaging visually substantiated a more extensive protective film at higher inhibitor concentrations, and EDS analysis corroborated these findings by detailing the elemental composition of the adsorbed layer. The observed reduction in inhibition efficiency with elevated temperatures suggests a thermodynamic effect, where increased temperatures diminish the adsorption of the inhibitor onto the metal surface. This comprehensive investigation establishes the potential of chamomile extract as an eco-friendly inhibitor for effectively mitigating corrosion on carbon steel in corrosive environments. The pinnacle of inhibition efficiency, reaching 96.55%, was achieved at the concentration of the inhibitor.

Investigation into Morphology of Cavitation Erosion-Corrosion Pits on the Surface of Carbon Steel

Nano-sized films associated with the ring areasformed around micropits in cavitation erosion experimentswere investigated. The corrosion behavior and vibratory cavitation erosion tests of mild carbon steel in 3% NaCldistilled water were carried out. The results showed that thenano-sized films associated with the ring areas formedaround micropits in cavitation and free cavitation tests havea similar shape. The study proved that the nano-structure and the ring areas formed around micropits are the result ofcorrosion effects and not as a result of thermal effectsrelated to the collapse of the bubbles.

Investigating the synergistic effect of iodide ion and Michelia alba leaf extract on carbon steel in 0.5 M H2SO4

The study examined the inhibitory effect of Michelia alba leaf extract (MALE) on carbon steel (CS) in 0.5 M H2SO4 solution. Furthermore, the investigation explored the effect of KI to enhance the protection provided by MALE. The study demonstrates that both MALE and KI have corrosion inhibiting properties on CS in acidic solutions. However, when MALE and KI are combined, they exhibit a greater inhibitory effect. Corrosion inhibition efficiency was limited to 86.55 % with 400 mg/L MALE. The maximum corrosion inhibition efficiency was 51.84 % when 400 mg/L KI was used alone. However, when 800 mg/L MALE was combined with 400 mg/L KI in 0.5 M H2SO4 solution, the efficiency increased to 95.02 %. This increase can be attributed to the synergistic effect between MALE and KI. The SEM and XPS results further confirmed that the addition of KI could be more effective in preventing the corrosion of CS. The theoretical calculations demonstrate that constituents found in the extract, which are rich in hydroxyl groups, benzene rings, N and S atoms have a higher probability of adsorption onto the CS surface in parallel, thereby increasing the efficiency of corrosion inhibition significantly.

Adsorption kinetics and inhibition mechanisms of a film-forming amine on carbon steel surfaces

In the present study, the inhibition mechanisms and the adsorption kinetics of a film-forming amine (N-oleyl-1,3-propanediamine, OLDA) were investigated on a carbon steel surface in various corrosive environments, relevant to industrial water/steam circuits. In situ electrochemical characterizations including Electrochemical Impedance Spectroscopy (EIS) and polarization curves were combined with ex situ surface analysis, such as Polarization Modulation Infrared Reflection Absorption Spectroscopy (PM-IRRAS) and Raman Spectroscopy. OLDA acts as a mixed inhibitor for all the studied conditions. In a deaerated medium, OLDA adsorption is temperature-independent (25 °C–50 °C) and PM-IRRAS analyses reveal the formation of a monolayer (thickness of about 1.6 nm) on the steel surface. In aerated media, mixed OLDA/corrosion products layers are formed exceeding the monolayer thickness (about 20 nm). Finally, the presence of a well-defined time constant in the high frequency range in impedance spectra is correlated with the accumulation of OLDA molecules with corrosion products.

Clathrate Hydrate-Solid Surface Adhesive Shear Strength Measurements on Carbon Steel Surfaces.

Oil and gas flowlines operating in subsea or cold terrestrial environments face the risk of forming hydrate deposits and plugs. The pressure differential across a hydrate plug can cause the plug to detach from the pipe wall and travel through the pipeline, potentially impacting a bend or inline equipment, causing damage or injury to personnel. Therefore, the hydrate-solid adhesive shear strength is of interest in estimating the maximum allowable differential pressure across a plug during depressurization procedures before the plug is likely to detach from the pipe wall. Quantifying the changes in adhesive shear strength with time and operational conditions is essential in estimating the potential of hydrate deposits to slough from the pipe wall. This work used a force meter with a cylindrical "pig-style" probe mounted to a single axis motorized test stand to measure the force required to dislodge model THF structure II hydrate plugs in carbon steel pipes. Profilometry measurements were used to quantify the mean surface roughness and relative peak frequency of the pipe surfaces. Contact angle measurements were performed of a water droplet on pristine, sanded, and corroded pipe surfaces immersed in nonpolar solvents. The adhesive shear strength of the hydrate plugs was measured for different subcoolings, solid surface roughness, and surface wettabilities. Subcooling was shown to impact the hydrate-solid adhesive shear strength, and a mixed adhesive/cohesive failure mechanism was observed at the highest subcooling tested. The surface roughness and wettability were also shown to influence the hydrate-solid adhesive shear strength, with readily wetting corroded and sanded carbon steel surfaces resulting in greater interface adhesive strength than the pristine carbon steel system. This is likely due to a Wenzel wetting mode at the interface, resulting in a higher ratio of actual to apparent wetted area as well as establishing a mechanical interlocking mechanism.