Carbon Steel Research Articles

PERFORMANCE EVALUATION OF CASTOR SEED OIL AND MINERAL OIL BASED CUTTING FLUIDS IN TURNING AISI 1020 MILD STEEL

There is a global challenge with the roles of cutting fluids in machining operations with the setback associated with the use of mineral oil; the desire for eco – friendly, health related hazards elimination, biodegradability, minimized disposal cost and so on cannot be overemphasized. In this study, the focus is on comparing the performance of castor oil based cutting fluid (CBCF) with mineral oil based cutting fluid (MBCF) during turning of AISI 1020 Mild steel workpiece. Castor seed oil was used to formulate the oil-in-water emulsion cutting fluid with characteristics showing viscosity of 0.830 mm 2/s, pH value of 8.47, high stability, corrosion resistant and milky in colour. The FAC shows the ricinoleic acid as 86.43%. Palmitic, (0.72%) and Stearic, (0.85%) are the major saturated fatty acid. Octanoic acid, (0.34%) and Pentanoic acid, (1.38%) are the other fatty acid present. An approximately 94.48% unsaturated fatty acid with main contributors being 86.43% ricinoleic acid, 4.93% oleic acid, 2.97% linoleic acid and 0.15% linolenic acid with others. The S/N ratio for CBCF and MBCF are 800 CS, 0.4 FR and 0.8 doc; and 800 CS, 0.4 FR and 0.6 DOC respectively with R-sq and R-sq(pred) values as 95.52% and 92.83 under the CBCF and lastly 94.33% and 91.25% under the MBCF for surface roughness respectively. The R-sq and R-sq(pred) values are 88.48 % and 81.57 % under the CBCF and lastly 97.39 % and 95.82 % under the MBCF for tool wear respectively.

Study of Design and Analysis of S-glass Fiber Reinforced Epoxy Polymer Metal Laminate Composites in the Application of Propeller Shafts

The propeller shafts are utilized to transmit power from gear box to rear wheels in automobiles. It is found that the weight, cost, critical speed and buckling of shafts are the serious issues in conventional metallic propeller shafts. The propeller shafts made up of composite material are best suited for LMV due to single piece manufacturing. The fiber metal laminate propeller shafts are getting popular as the metal liner adds extra strength, rigidity and acts as a substrate and avoids leaking during manufacturing. The propeller shaft of light motor vehicle was selected for study. S-glass fibers, epoxy and a thin mild steel liner are the materials chosen. The design of the shaft was carried out according to ASME Standard code of design. The ply orientation and stacking sequence are selected as [±45°, 0°, 90°], to increase the torsional strength, enhance natural frequency and buckling strength respectively. The finite element analysis of the propeller shaft is carried out in Ansys APDL. It is found from the analysis that the weight, torsional strength, torsional stiffness and natural frequency of the S-glass fiber reinforced Epoxy Metal Laminate (FML) composites are superior than the conventional C-35 alloy steel material, and hence can be an alternative to the conventional alloy steel shaft.

Chitosan grafted with gallic acid and cerium dioxide hybrid nanocomposites as environmentally friendly corrosion inhibitors for mild steel: An experimental and computational study

Chitosan grafted with gallic acid (CS-GA), along with CS-GA doped with CeO2 nanoparticles (CS-GA-CeO2) were synthesized as novel environmentally friendly mild steel corrosion inhibitors. The formation of these derivatives was confirmed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), hydrogen nuclear magnetic resonance spectroscopy (1H NMR), and thermal analysis (TGA). Based on potentiodynamic polarization curves (PDP) measurements, the inhibitors acted primarily as hybrid inhibitors, while following the Langmuir adsorption theory model. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy(XPS) and 3D surface profiles, confirmed that CS-GA-CeO2 adsorbed on the mild steel forming a protective layer thus preventing the invasion of corrosive media. The corrosion protection mechanism of chitosan derivatives was investigated by molecular dynamics simulations. Electrochemical measurements were used to investigate the corrosion inhibition by CS-GA and CS-GA-CeO2 on mild steel in a 3.5 % NaCl solution. At room temperature, the highest inhibition efficiency (93.58 %) was achieved at 200 ppm CS-GA-CeO2. Modified chitosan nanocomposites were confirmed as promising corrosion inhibitors.

Design of Mold Flipper in an Effort to Improve The Efficiency of Mold Maintenance Process

Molding is a production process by forming raw materials using a rigid frame or model used in the manufacturing industry to mold materials called a mold. Injection molding is a technique in the manufacturing industry for molding thermoplastic materials. Thermoplasctic materials commonly molded with Injection Molding techniques are Polystyrene, Acrylonitrile Butadiene Styrene (ABS), PMMA (Polymethyl Methacrylatic) and others. The purpose of this research is to design and build a flipper molding tool for an easier and more efficient mold maintenance process. This research uses descriptive methods. Data is taken through direct observation and through reference books both from companies and websites and journals related to the report material. The data obtained was analyzed using descriptive analysis. it is found that the material used in the work is Carbon Steel (S45C). The process of making Flipper Clamps Mold has several stages, namely the Design Making Process, Material Selection Process, Cutting Process, Milling Process, Grinding Process, Drilling Process, Welding Process, and Assembly Process. With this Flipper Clamping tool, it is hoped that it can make it easier for operators to maintain and repair molds, because the previous mechanism requires two operators to flip molds that weigh more than 200 kg, now they only need to flip by turning the lever of this tool.

Structural frequency-based maintenance management method for steel truss bridges under atmospheric corrosion

Deterioration of steel truss bridges due to atmospheric corrosion can result in a degradation of performance that fails to meet basic safety requirements before the structure has fulfilled its design life. In order to prevent unexpected costs and premature structural damages caused by deterioration in steel truss bridges, cost-effective corrosion protection and maintenance strategies are required. In this study, a novel maintenance management method was proposed to keep the structural frequencies of steel truss bridges in between predefined boundaries throughout the service life. To pursue this aim, preventive and essential maintenance techniques were applied to provide appropriate atmospheric corrosion protection to steel truss bridges in a cost-effective way. Different repetitive repainting intervals were used for preventive maintenance, and member replacement alternatives with different ratios of total members were applied for essential maintenance approaches. Moreover, the replacement of members using conventional carbon steel, or A709-50CR was investigated separately. For the illustration of the proposed maintenance management method, a planar and a spatial steel truss bridge were selected from the literature, and maintenance strategies were applied considering two different corrosion classes. Life cycle cost analyses of steel truss bridges were conducted to evaluate different maintenance alternatives. Consequently, a cost-effective maintenance strategy was determined for each steel truss bridge in different corrosion environments.

Bioinduced corrosion of carbon and alloyed steel by thermophilic microorganisms in the presence of uranyl ions under anaerobic conditions

Intensification of corrosion in short-term experiments on carbon (СS) and stainless (SS) steel as materials for underground radioactive waste disposal by thermophilic microbial communities isolated from neutral (Tuva region) and alkaline thermal radionuclide-enriched environments (Tau Tona mine) in the presence of uranium under anaerobic conditions was studied. The corrosion rate of carbon and stainless steel in the presence of the Tau Tona culture increased up to 14 and 3.7 times, respectively. The increase correlated with the predominance of metal-reducing bacteria in the culture. The culture from Tuva, dominated by fermentative bacteria, increased the corrosion rate 6 to 4 times, depending on the type of steel and organic substrate. The main mechanism of microbial corrosion of both types of steel was the dissolution of passivating corrosion products, mainly magnetite, due to their reduction by iron-reducing bacteria or chelation by metabolic products of fermenting bacteria. Surface corrosion was observed on carbon steel and pitting on stainless steel. In the presence of uranyl ions, the corrosion rate of both types of steel increased up to 19 `. Uranyl ions can be reduced to UO2 by microorganisms and will not further affect steel oxidation, furthermore, accumulation of reduced forms of uranium in corrosion products may passivate steel corrosion. It was found that in the presence of organic substances in the environment it can intensify chemical corrosion processes of both types of steel due to the complexation of steel corrosion products, preventing the formation of a passivating corrosion layer. Thus, in the presence of acetate, the corrosion rate of black and stainless steel was 12–36 % higher, in the presence of trehalose it increased the corrosion rate by 1–24 %.

Corrosion of AISI1018 and AISI304 steel exposed to sulfates

This research analyses the behavior of corrosion, durability, and quality of reinforced concrete samples coated with two different materials when exposed to contaminated soil with sulfates. The initial assessment involved evaluating the water absorption rate of the coating materials before and after exposure to a solution containing 3% Na2SO4 + 3% MgSO4 + 3% K2SO4 + 3% CaSO4 to determine their durability. The corrosion potential and linear polarization resistance technique were employed to measure the corrosion rate. Carbon steel and AISI 304 steel bars were tested alongside a stainless counter electrode. The findings indicate that the solvent-based coating exhibited superior performance, demonstrating reduced corrosion and water absorption rates. Additionally, the presence of sulfates led to the formation of a surface layer on the concrete, initially aiding in limiting water penetration. However, over time, this layer eventually causes damage to the concrete from the inside out.

Evaluation of N80 Carbon Steel Corrosion in 15 wt.% HCl Using Isatin-hydrazones: A Comprehensive Approach with Chemical, Electrochemical Techniques, and DFTB Calculations

The adverse effects of corrosion on industrial metals, particularly N80 carbon steel under acidic conditions, call for developing effective corrosion inhibitors. Due to their structural and electrical properties, isatine-hydrazones have emerged as possible corrosion inhibitors. This study investigates the corrosion inhibition capabilities of two specific Isatin-hydrazones, (E)-1-octyl-3-(2-(5-oxo-4,4-diphenyl)-4,5-dihydro-1H-imidazol-2-yl)hydrazono)indolin-2-one (OPHIHI) and (E)-3-(2-(5-oxo-4,4-diphenyl)-4,5-dihydro-1H-imidazol-2-yl)hydrazono)indolin-2-one (OIHIHI), on N80 carbon steel in a highly acidic medium. The study assessed the corrosion inhibition efficacy of OIHIHI and OPHIHI using both computational and experimental approaches. Weight loss measurements, potentiodynamic polarization, and electrochemical impedance spectroscopy were used in the experiments. In contrast, density functional theory (DFT), molecular dynamics (MD), and tight-binding density functional theory (DFTB) were used in the computational analyses to elucidate the interaction mechanisms between the inhibitors and metal surfaces. The experiment demonstrated that both OPHIHI and OIHIHI effectively reduce corrosion rates in a 15 wt.% HCl solution at 303 K, achieving an inhibition efficiency of 96 % and 92 %, respectively, at an optimal 5 × 10−3 mol/L concentration. These inhibitors were discovered to form protective layers on the N80 carbon steel surface, offering mixed protective qualities (cathodic and anodic protection) with a preponderance of cathodic protection against carbon steel corrosion in 15 wt.% HCl. Computational studies supported the experiment's findings by demonstrating that isatin-hydrazones' superior electronic properties enabled them to form robust covalent bonds with the Fe (110) surface. Based on these results, OPHIHI and OIHIHI could be used as corrosion inhibitors in the oil and gas industry, particularly under highly acidic conditions.

The upper bound of the buckling stress of axially compressed carbon steel circular cylindrical shells

Abstract The buckling stress of axially compressed circular cylindrical shells (CCSs) is highly sensitive to imperfections. The literature proved that it is hard to generalize the imperfections and the designers are encouraged by the Eurocode EN 1993:1-6 (2007) to conduct geometric and material nonlinear with imperfections analysis (GMNIA) considering different possible forms of imperfections for the shell under design. As GMNIA type of analysis is difficult and requires highly skilled engineers, knowledge of the upper limit of the buckling stress serves as a guide and prevents the overestimation of the shell buckling resistance. It also encourages average skill designers to attempt GMNIA as far as the maximum possible limit is known. Thus, the objective of this study is to provide the upper bound of the buckling stress of carbon steel CCSs. Geometric and material nonlinear analysis (GMNA) of perfect circular cylindrical shells for a wide range of R/t ratio is conducted. It has been found that for cases of small and intermediate R/t values the buckling stress can be predicted by GMNA while the elastic buckling controls those of larger R/t values. The limiting R/t values depend on the steel grade and have been derived for the available standard grades of carbon steel. The obtained results are presented in terms of simplified formulas and a design chart to be used by engineers. Application of the proposed upper bound in simplified design approaches using knock down factor (KDFs) has also been discussed.

PRODUCTION OF CARBON DIOXIDE CORROSION INHIBITORS OF STEEL FROM DIAMINES AND TALL OIL FATTY ACIDS

Substituted imidazolines are one of the most common and effective surface-acting metal corrosion inhibitors. The main tasks of today are to reduce their cost and increase their hydrolytic stability, which is achieved through a targeted choice of the nature and structure of long-chain carboxylic acids in the synthesis of imidazolines. Another way to reduce the cost of producing corrosion inhibitors based on aliphatic ethylenediamines is to use imidazoline precursors – amidoamines and ammonium salts - to protect against corrosion, the production of which is much less energy-consuming.The synthesis of active substances of carbon steel corrosion inhibitors in the reaction of diamines with fatty acids of tall oil was carried out. It is shown that depending on the temperature of the reaction and the introduction of the catalyst – polycationite CU-2-8 - it is possible to selectively obtain derivatives of imidazolines, amidoamines, and ammonium salts, which are capable of inhibiting carbon dioxide corrosion of steel in mineralized water at 60 °C with a degree of protection from 85 % to 91 %. It is noted that the protective effect of amidoamines and ammonium salts is practically not inferior to the action of imidazolines.

Study of the thermal effect of hot and cold working on the mechanical properties of medium carbon steel

Medium carbon steel is widely used in industries due to its favourable strength and flexibility. However, they are highly prone to deformation processes that affect their impact resistance and corrosion rate. This research examines the effects of hot and cold working on the mechanical properties of medium-carbon steel. Experimental tests were conducted on medium carbon steel samples subjected to hot and cold working treatment procedures via funnels for the hot working. Deformation techniques such as rolling and bending are employed by subjecting the materials to a high temperature of 900oC. At the same time, in this study, cold working uses room temperature between 0oC to 22 oC for both rolling and bending. The results show that hot bending improves the hardness property in the bending analysis, having 185.64, as opposed to cold bending, which is 174.33. It can be seen that the cold rolling treatment of medium carbon steel increases the hardness property by 179.84 compared with hot rolling techniques, which have a hardness of 161.63. The results from the rolling test show that the tensile stress at the yield point of the zero slopes is lower during the hot working process, having 598.05090 MPa, compared with the cold working results of 665.43718 MPa. However, the results of the elasticity modules show that hot working increases it with a value of 32885.24170 MPa compared with 28923.17810, respectively. It can be concluded that parameter optimization of the specification of medium carbon steel determined the specific treatment needed for the manufacturing industry to produce quality materials.

Eco-Friendly Waterborne Polyurethane Coating Modified with Ethylenediamine-Functionalized Graphene Oxide for Enhanced Anticorrosion Performance.

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.

Synergistic effects of mixed microorganisms on the corrosion of X65 carbon steel in actual reinjection water

Complex microbiological interactions in reinjection water can lead to severe corrosion of pipelines. In this study, X65 specimen was used for corrosion simulation experiments to explore the microbiologically influenced corrosion (MIC) and mechanism in actual oilfield reinjection water. The results of scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) showed that the X65 carbon steel was severely corroded by microorganisms, with the maximum localized corrosion pit depth of 15.04 μm after 28 days of immersion. Electrochemical analysis and weight loss measurement further confirmed that the mixed microorganisms caused serious corrosion of X65 carbon steel, and the maximum corrosion rate was 0.249 mm/y. Furthermore, microbial community structure determination showed that mixed microorganisms in the actual reinjection water formed a corrosive biofilm on the surface of X65 steel, inducing severe pitting corrosion, which was mainly attributed to the synergistic effect of Pseudomonas, sulfur-oxidizing bacteria (SOB), sulfate-reducing bacteria (SRB) and methanogenic archaea. The results of this study have important guiding significance for the identification of MIC process for actual water samples of the oilfield and the timely adjustment of MIC control measures.

Performance of Acetone Extract of Anthocleista grandiflora as a Potential Bioinhibitor on Corrosion Behavior of Carbon Steel in Seawater Environment

In this study, we evaluated the potential of Anthocleista grandiflora leaf (AGL) plant extract as an environmentally friendly and cost-effective corrosion inhibitor for carbon steel in seawater. We employed various experimental methods, including gravimetric analysis, potentiodynamic polarization, electrochemical impedance spectroscopy, scanning electron microscopy (SEM) and Fourier transform infrared spectrophotometry (FTIR). Our findings indicate that increasing the concentrations of the AGL extract results in higher charge transfer resistance (Rct ) and reduced double-layer capacitance (Cdl ), suggesting the effective adsorption of AGL extract on the surface of carbon steel. The inhibition efficiencies were notably high, 98.7%, 92.40%, and 90.7% determined with gravimetric analysis, potentiodynamic polarization, and electrochemical impedance spectroscopy, respectively. Polarization analysis revealed that the AGL extract acted as a mixed-type inhibitor. Moreover, the results obtained from different techniques exhibited a consistent agreement. The SEM images revealed that the surface layer formed by the AGL extract on the mild steel surface further devoids the surface from pitting as the extract concentration increases. Comparative analysis with similar bio-based inhibitors suggested that the tested AGL extract holds a significant promise as a corrosion inhibitor for carbon steel in seawater. Therefore, our findings support the recommendation of utilizing this AGL extract as an effective anti-corrosion agent in marine industries, owing to its green, low-cost, and efficient characteristics.

Kinetic and Thermodynamic Properties of Locally Sourced Calcium in the Zinc Phosphating of Mild Steel

Kinetic and Thermodynamic Properties of Locally Sourced Calcium in the Zinc Phosphating of Mild Steel

A Study on the Corrosion Inhibition Impact of Newly Synthesized Quinazoline Derivatives on Mild Steel in 1.0 M HCl: Experimental, surface morphological (SEM-EDS and FTIR) and computational analysis

Two new quinazoline derivatives were investigated in this research, namely 12-(4-methoxyphenyl) and 3,3-dimethyl-12-(4-nitrophenyl)-3,4,5,12-tetrahydrobenzo[4,5]imidazo[2, 1-b]quinazolin-1(2H)-one (Q-NO2). In 1M hydrochloric acid (HCl), -3,3-dimethyl-3,4,5,12-tetrahydrobenzo[4,5]imidazo[2,1-b]quinazolin-1(2H)-one (Q-OMe) proved to be an extremely effective corrosion inhibitor for mild steel. The maximum inhibition efficiencies of 94.7% for Q-NO2 and 96.7% for Q-OMe were achieved when the performance of the inhibitors was evaluated using potentiodynamic polarization (PDP), electrochemical frequency modulation (EFM) and electrochemical impedance spectroscopy (EIS). According to these findings, the Q-NO2 and Q-OMe molecules have a remarkable ability to generate a dense, resistant protective film on the mild steel surface. This protective film acted as a barrier, effectively blocking the penetration of corrosive ions and their interaction with the mild steel substrate. The adsorption characteristics of these inhibitors on the mild steel surface conform to the Langmuir adsorption isotherm. PDP experiments show that Q-NO2 and Q-OMe act as mixed-type inhibitors for mild steel in 1.0M HCl. Surface characterization by energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) determined that a protective layer had formed on the steel surface, preventing corrosion. The experimental results were corroborated by theoretical insights from density functional theory (DFT), which further clarified the molecular adsorption processes. This work highlights the potential of Q-NO2 and Q-OMe as effective inhibitors to protect mild steel in acidic situation.

Study of multifaceted eco-friendly nanoparticle zinc coating incorporation on mild steel.

Mild steel's versatile application in various fields makes it a pivotal material, yet its vulnerability to corrosion demands effective protection methods. This work explores the potential synergy between plantain peel (PP) and snail shell particle (SSP) nanoparticles when combined in a Zn–MgO matrix to improve corrosion resistance in mild steel coatings. After a thorough investigation of various bath compositions and process conditions, the ZnO–MgO–20SSP–20PP coating was found to have improved electrical characteristics, decreased thickness with high-quality films, higher hardness (78 HRB), and excellent corrosion resistance. Corrosion tests showed a notable decrease (∼70% for the ZnO–MgO–20SSP–20PP sample) in the rate of corrosion, and optical micrographs confirmed the coating's capacity to reduce damage. A reliable predictive model (ANOVA) was produced by mathematical optimization utilising a central composite design, which highlighted the interplay of SSP and PP concentrations on corrosion rate. This extensive study provides eco-friendly alternatives for improved mild steel corrosion prevention by showcasing the diverse contributions of SSP and PP nanoparticles.

Corrosion Resistance Improvement of Mild Steel

Abstract Corrosion’s devastating consequences have become a big issue all over the world. One of the corrosion damage aspects are related to decontamination solutions which are essential for rapid degradation of toxic agents. The decontamination solutions should be non-corrosive to avoid deterioration of steel container. Decontamination solutions comprising have high chlorinating activity so they have a corrosive effect on mild which are used in fabrication of storage tanks. In this case, using inhibitors is one of the most effective strategies to limit the rate of corrosion. This work describes the effect of different compounds; (zinc chromate, cinnamaldehyde, sodium tripolyphosphate, zinc ortho-phosphate, ammonium molybdate and thiourea) on the rate of corrosion of mild steel within dichloroisocyanuric acid decontamination solution. Meanwhile, these inhibitors should not affect active chlorine content which is responsible for the decontamination process. By using kelthoff and AquaChec® methods for measuring active chlorine, it was found that only zinc chromate passed the tests. For measuring electrochemical behaviour of mild steel in decontamination solutions, different techniques were used. Zinc chromate inhibition on mild steel in a 0.5% dichloroisocyanuric acid solution at different temperatures (298–313 K) were studied utilising electrochemical impedance spectroscopy, weight loss, and potentiodynamic polarisation. The results reveal that zinc chromate is an excellent mild steel corrosion inhibitor in dichloroisocyanuric acid, with an inhibition efficacy of 96% at a concentration of 0.005 M. Finally, surface morphology of mild was also investigated using SEM.

Comprehensive Assessment of the Corrosion Inhibition Properties of Quinazoline Derivatives on Mild Steel in 1.0 M HCl Solution: An Electrochemical, Surface Analysis, and Computational Study

The efficacy of two compounds, namely 12-(4-chlorophenyl)-3,3-dimethyl-3,4,5,12-tetrahydrobenzo[4,5] imidazo[2,1-b]quinazolin-1(2H)-one (Q-Cl) and 3,3-dimethyl-12-phenyl-3,4,5,12-tetrahydrobenzo[4,5]imidazo[2,1-b]quinazolin-1(2H)-one (Q-H), in inhibiting corrosion on mild steel in 1.0M hydrochloric acid was evaluated. Surface analytical techniques and electrochemical procedures were employed for examination. The results demonstrated that both Q-Cl and Q-H significantly inhibit corrosion. Specifically, Q-Cl achieved an inhibition efficiency of 85.2% at a concentration of 10⁻³ M, while Q-H exhibited a higher inhibition efficiency of 91.5%. Electrochemical investigations suggested that both Q-Cl and Q-H acted as inhibitors of mixed-type corrosion. These chemicals efficiently prevented metal corrosion through adsorption, conforming to Langmuir's adsorption isotherm model. The adsorption mechanism of corrosion inhibition was further supported by surface investigations and scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX). Additionally, Density Functional Theory (DFT) and other computational approaches were employed to study the anti-corrosion mechanism of Q-Cl and Q-H. These simulations yielded theoretical results that aligned with the preceding experimental findings.

Insight into the corrosion inhibition mechanism of mild steel St1 in 2 M H2SO4 electrolyte by azithromycin

Mild steel is essential in modern industry due to its favorable mechanical properties and economic availability. However, its high susceptibility to corrosion, especially in acidic environments, poses a significant challenge, reducing service life, increasing operating costs, and raising the risk of failures. This study investigates the corrosion inhibition mechanism of mild steel St1 in a 2 M H2SO4 solution at various temperatures using the broad-spectrum antibiotic azithromycin (AZM). Experimental results indicate that AZM presence increases the polarization resistance of mild steel in the acidic solution. AZM acts as a mixed-type inhibitor, influencing the kinetics of both cathodic and anodic processes. The introduction of 200 mM AZM leads to an increase in the polarization resistance of the steel electrode in 2 M H2SO4 by up to 2.4 times. The inhibition mechanism involves forming a protective layer of protonated AZM forms on the negatively charged Fe surface. These protonated forms can also adsorb on cathodic areas, competing with hydronium ions (H3O+) and thereby inhibiting hydrogen evolution processes. The protective effect of AZM diminishes with increasing temperature of the corrosive environment, as confirmed by Monte Carlo simulations showing decreased adsorption energies for AZM and its protonated forms at higher temperatures. An assessment of the protective effect of 200 mM AZM showed that an increase in the temperature of the corrosive environment from 293 to 333 K leads to a decrease in the protective effect by almost 5.6 times. Quantum chemical calculations determined the reactivity of AZM and its protonated forms, identifying the molecular groups involved in the adsorption mechanism.