Corrosion Inhibition Characteristics Research Articles

Synergistic corrosion inhibition of mild steel by chalcone derivatives and KI in acidic media via computational and experimental methods

The corrosion inhibition characteristics of chalcone 4-hydroxy-6-methyl-3-(3-phenylacryloyl)-2H-pyran-2-one derivatives with different functional groups (H, Cl, -CH3, -NO2, -OCH3) studied employing density functional theory (DFT). The study identified the CH-OCH3 derivative as the most effective inhibitor among the compounds analysed. This derivative was synthesized and characterized through IR, 1H NMR and 13C NMR spectroscopy. The CH-OCH3 inhibitor then studied for its mild steel corrosion inhibition capability using Electrochemical and surface analysis in 1 M HCl. CH-OCH3 inhibitory efficacy rises in proportionately with their concentration, according to electrochemical results and reaches 85.4 % at 10−3 M. Potentiodynamic polarization revealed that it operates as mixed-kind of inhibiting nature. CH-OCH3 adheres to the Langmuir isotherm when they bind over the mild steel surface. The deposition of the inhibitors on metal surface is additionally verified by surface study utilizing AFM. Additionally, the influence of KI addition over CH-OCH3 inhibition property has been studied.

A curcumin quantum dot blended polyacrylonitrile electrospun nanofiber coating on 316 L SS for improved corrosion resistance in the marine environment.

Corrosion of 316 L SS is a significant global concern and recently polymeric nanofibers have been gaining attention for their potential in enhancing the corrosion resistance of metals. In this work, an electrospinning technique was deployed for the deposition of a curcumin quantum dot (CMQD) blended polyacrylonitrile (PAN) nanofibrous anticorrosive coating on 316 L SS. The optimized PAN-CMQD coated samples obtained from the weight loss studies were examined to assess their corrosion inhibition characteristics in 3.5 wt% NaCl electrolyte as the corrosion environment using potentiodynamic polarization and electrochemical impedance spectroscopy. The PAN-CMQD coated samples showed two-order reduction in I corr compared to the uncoated 316 L SS. The results of the long-term analysis for 30 days revealed no significant changes in I corr and E corr values and no pit formation for PAN-CMQD coated samples, proving the longevity of the coating. Thus, this work will serve as a cost-effective futuristic strategy for the large-scale development of anticorrosive nanofibrous coatings for enhancing the corrosion resistance behavior of metals and alloys in various industrial sectors.

Research on the corrosion inhibition performance and mechanism of pyrimidine quaternary ammonium salt

PurposeAt present, research on the preparation of corrosion inhibitors using modified pyrimidine derivatives is still blank. The purpose of this study is to synthesize a new cationic mercaptopyrimidine derivative quaternary ammonium salt, known as DTEBTAC, that can be used as a corrosion inhibitor to slow down the metal corrosion problems encountered in oil and gas extraction processes.Design/methodology/approachA new corrosion inhibitor was synthesized by the reaction of anti-Markovnikov addition and nucleophilic substitution. The weight loss method was used to study the corrosion inhibition characteristics of synthetic corrosion inhibitors. Electrochemical and surface topography analyses were used to determine the type of inhibitor and the adsorption state formed on the surface of N80 steel. Molecular dynamics simulations and quantum chemistry calculations were used to investigate the synthetic corrosion inhibitor’s molecular structure and corrosion inhibition mechanisms.FindingsThe results of the weight loss method show that when the dosage of DTEBTAC is 1%, the corrosion rate of N80 steel in hydrochloric acid solution at 90? is 3.3325 g m-2 h-1. Electrochemical and surface morphology analysis show that DTEBTAC can form a protective layer on the surface of N80 steel, and is a hybrid corrosion inhibitor that can inhibit the main anode. Quantum chemical parameter calculation shows that DTEBTAC has a better corrosion inhibition effect than DTP. The molecular dynamics simulation results show that DTEBTAC has stronger binding energy than DTP, and forms a network packing structure through hydrogen bonding, and the adsorption stability is enhanced.Originality/valueA novel cationic mercaptopyrimidine derivative quaternium-ammonium salt corrosion inhibitor was designed and provided. Compared with the prior art, the preparation method of the synthesized mercaptopyrimidine derivative quaternary ammonium salt corrosion inhibitor is simple, and the presence of nitrogen-positive ions, sulfur atoms and nitrogen-rich atoms has an obvious corrosion inhibition effect, which can be used to inhibit metal corrosion during oil and gas field exploitation. It not only expands the application field of new materials but also provides a new idea for the research and development of new corrosion inhibitors.

Green Synthesizing and Corrosion Inhibition Characteristics of Azo Compounds on Carbon Steel under Sweet Conditions: Experimental and Theoretical Approaches.

The deterioration of carbon steel in saline solutions enriched with carbon dioxide represents a significant challenge within the oil and gas industry. So, this study focuses on the design and structural analysis of four azo derivatives: 4-(2-quinolinylazo)-catechol (AZN-1), 4-(4-phenoxyphenylazo)-1-naphthol (AZN-2), 4-(4-pyridylazo)-1-naphthol (AZN-3), and 4-(2-pyridylazo)-1-naphthol (AZN-4), and their first application as effective corrosion inhibitors for carbon steel in a carbon dioxide saturated 3.5% sodium chloride solution. Spectroscopic methods were used to characterize the structural configurations of these compounds. The corrosion protection properties of these compounds on carbon steel in a carbon dioxide saturated 3.5% sodium chloride solution (under sweet conditions) were investigated using Tafel polarization (PDP), electrochemical impedance spectroscopy (EIS), and field emission-scanning electron microscopy (FE-SEM) studies. The results indicate that the inhibition efficiency increases as the concentration of the inhibitors increases. There is a notable agreement between the results obtained from the PDP and EIS measurements, supporting the findings. Moreover, the results displayed that these compounds had significant corrosion protection capabilities at low concentrations, ranging from 91.0 to 98.3% at an additive concentration of 5 × 10-4 M. The PDP profiles showed that these compounds acted as mixed inhibitors, and their adsorption behavior followed the Langmuir isotherm model. Besides, EIS results corroborate the adsorption of AZN compounds through a reduction in double-layer capacitance (Cdl) alongside an augmentation in polarization resistance (Rp) after the addition of AZN compounds into the corrosive solution. Field emission scanning electron microscopy (FE-SEM) and Fourier-transform infrared spectroscopy (FTIR) analysis confirmed the formation of a protective layer on the surface of carbon steel when these inhibitors were applied. In addition, computational calculations and Monte Carlo simulations were performed to support the experimental observations, gain insights into the adsorption properties, and elucidate the corrosion inhibition mechanisms of these compounds.

Characterization of the aluminium-air battery utilizing a polypropylene separator with corrosion inhibition ability

Battery energy storage systems are widely used in modern electronic devices and electric vehicles. Metal-air batteries are among the electrochemical energy storage systems that provide high energy density and eco-friendly solutions. Aluminium-air batteries hold a significant advantage with their high theoretical specific energy and have the potential to replace lithium-ion batteries in the future. In this study, the electrical performance and corrosion inhibition characteristics of a polypropylene-based single and dual electrolyte system for aluminium-air batteries were investigated experimentally. The study revealed that a polypropylene separator can reduce the corrosion of the aqueous aluminium-air battery system by up to 40 %, improving the anodic utilization efficiency to 93 %. Electrochemical impedance spectroscopy analysis was used to characterize the single and dual electrolyte aluminium-air battery and propose equivalent circuit models. Compared to 1 M KOH electrolyte in a single electrolyte system, the solution resistance of a dual electrolyte aluminium-air battery was reduced by about 40 % using a combination of 1 M of KOH electrolyte and 1 M of H2SO4. This reduction is attributed to the enhancement of the oxygen reduction reaction at the air cathode. A high KOH electrolyte concentration will increase the corrosion of the aluminium anode but can improve the battery’s voltage. At 3 M KOH electrolyte, the plateau voltage is recorded at about 0.6 V while the discharge time reached 44 min when using aluminium alloy 6061 as the anode. The battery model developed in this work provides a fundamental basis for predicting the performance of aluminium-air battery packs.

Electrochemical behaviour of sputter-coated titanium films on AZ31 magnesium alloy

Lightweight magnesium-based structural alloy AZ31 is normally prone to high corrosion in an aqueous environment. A detailed study is reported in this work on AZ31 Mg alloy coated with Ti thin films of different thicknesses by DC sputtering to investigate the capability of Ti coating to prevent corrosion of AZ31 under an aqueous environment similar to seawater. Ti films have been fabricated to 50, 100 and 150 nm thicknesses. Utilising grazing incidence-XRD and SEM, the films’ structure and microstructure were studied. The films were amorphous. Due to corrosion, interesting micro-structures evolved. Corrosion inhibition characteristics of the Ti films were characterised by electrochemical techniques such as potentiodynamic polarisation and impedance spectroscopy. Ti films with 100 nm and 150 nm thickness show a good inhibition capability. The corrosion mechanism was investigated using XPS and X-ray energy dispersive spectra.

Elucidating the mechanisms of novel thiazole-based corrosion inhibitors in carbon steel/HCl interface: An integrated approach combining experimental and computational studies

Corrosion inhibitors serve as a paramount strategy in the domain of metal protection. This study investigates the efficacy of two thiazole derivatives, namely methyl (E)-5-(4-chlorophenyl)-2-((2-(1-hydroxynaphthalen-2-yl)vinyl)amino)thiazole-4-carboxylate (ThN), and methyl (E)-5-(4-chlorophenyl)-2-((2-hydroxystyryl)amino)thiazole-4-carboxylate (ThP) in mitigating corrosion of carbon steel in a 1 mol/L hydrochloric acid medium. Electrochemical Impedance Spectroscopy (EIS), Potentiodynamic Polarization (PDP), Scanning Electron Microscopy coupled with Energy-Dispersive X-ray Spectroscopy (SEM-EDX), and X-ray Diffraction analysis (XRD) were used to experimentally assess the corrosion inhibition performance of compounds under study. Experimental results revealed a concentration-dependent increase in the corrosion inhibition efficiencies of the thiazole derivatives, with ThP achieving 90 % and ThN attaining 93 %. The adsorption of both compounds adhered to the Langmuir adsorption model, indicating a physicochemical inhibition mechanism. PDP analyses revealed a mixed-type inhibitory behavior. Furthermore, SEM-EDX assessments validated the ability of the thiazole derivatives to enhance corrosion resistance. XRD studies revealed a marked decrease in corrosion-associated peaks upon the introduction of thiazole derivatives. The potential of zero charge (PZC) for the carbon steel was ascertained via EIS, clarifying the adsorption mechanism. Employing Conductor like Screening Model for Realistic Solvents (COSMO-RS), the solvation properties of the compounds were evaluated, while Quantum Chemical Calculations (QCCs) and Molecular Dynamics (MD) simulations contributed insights into reactivity descriptors and adsorption configurations on the Fe(110) surface. This study highlighted the impact of the aryl group on the adsorption and corrosion inhibition characteristics of investigated compounds, offering valuable guidance for future design and development.

Imidazole-based ionic liquid as a corrosion inhibitor for aluminum alloy and it’s composite in HCl – A comparative study

The corrosion inhibition characteristics of ionic liquid 1-butyl-3-methyl-1H-imidazol-3-ium hexafluorophosphate (BMIF) on the corrosion behavior of 6061 Al–10 vol(%) SiC(p) composite (6061 Al-CM) and 6061 aluminum alloy(base alloy) were studied at different temperatures in 0.1 M HCl medium. The potentiodynamic polarisation technique and AC impedance spectroscopy (EIS) were used for corrosion rate determination. The obtained results showed that inhibition efficiencies increased with the increase in inhibitor concentration and temperature. The adsorption of BMIF on both 6061 Al–CM and base alloy was through chemisorption obeying the Freundlich adsorption isotherm. From the adsorption data thermodynamic parameters were evaluated. Surface morphology studies confirmed the adsorption of BMIF. Maximum inhibition efficiencies were 78 % for 6061 Al-CM and 68 % for base alloy for the concentration of 50 ppm BMIF in 0.1 M HCl at 323 K.

Corrosion inhibition and Adsorption characteristics of 3,4,5-trihydroxy-n-(3,4-dimethoxy benzylidene) benzo hydrazide schiff base on aluminium in different concentration of Hydrochloric acid environment

In the present paper we are presenting our studies on the synthesis of Schiff bases typically formed by condensation of 3,4,5-trihydroxy benzohydrazide and 3,4-dimethoxy benzaldehyde by microwave induced irradiation, reaction showed enhanced yield and less time, easier workup. The characterization of synthesized compound has been done on the basis of elemental analysis, spectral studies (FTIR,1HNMR, Mass) and surface morphology by Scanning Electron Microscopic (SEM). The structural composition of synthesized compound has been determined by X-Ray diffraction (XRD). The inhibition property of Schiff base 3,4,5-trihydroxy –N-(3,4dimethoxy benzylidene) benzo hydrazide on the corrosion of aluminum in 0.5N HCl,1NHCl, 2N HCl were studied using weight loss technique and electrochemical studies revealed mechanistic aspects of corrosion inhibition like potentiodynamic polarization measurements indicated the nature of inhibitor is a mixed type and impedance studies supported the formation of a protective layer of inhibitor on a metal surface. Adsorption of the inhibition molecule on aluminium surface was consistent with the Langmuir isotherm.

DFT, Fukui indices, and molecular dynamic simulation studies on corrosion inhibition characteristics: a review

DFT, Fukui indices, and molecular dynamic simulation studies on corrosion inhibition characteristics: a review

ZIF-8 and benzimidazole co-modified h-BN for enhancing anti-corrosion performance of epoxy coatings

Two-dimensional hexagonal boron nitride (h-BN) has excellent corrosion resistance and barrier ability, showing unique advantages in the field of anti-corrosion. The h-BN was assembled with Zeolite imidazolate framework material (ZIF-8) and benzimidazole (BI), and an active filler (h-BN/ZIF-8@BI) with shielding and active corrosion resistance was prepared. Zeolite imidazolate framework material was in-situ grown on h-BN surface and loaded with benzimidazole (BI), prepared an active anticorrosive filler with high shielding property (h-BN/ZIF-8@BI). The microstructure, crystal form, element composition, corrosion inhibition ability and thermal stability of h-BN/ZIF-8@BI were studied. The barrier, corrosion inhibition and anti-friction properties of EP/h-BN/ZIF-8@BI combined with F51 epoxy resin were explored. EIS test shows that the corrosion inhibition efficiency of h-BN/ZIF-8@BI is as high as 81.8 %. The impedance modulus of the steel matrix protected by the composite coating was about 2 orders of magnitude higher than that of the control sample, showing excellent barrier ability. In addition, the salt spray test proves that the composite coating has excellent corrosion inhibition characteristics. Taber testing machine shows that the wear mass loss of EP/h-BN/ZIF-8@BI coating is 34.5 % lower than that of EP coating. This work provides a novel idea for the preparation of high barrier, active anticorrosive and wear resistant anticorrosive coatings, and provides a new horizon of the composite coatings.

Anticorrosive properties of Eucalyptus (Nilgiris) leaves extract on 2S grade aluminium in acid solutions

The study is on the application of Eucalyptus leaves extract (ELE) as anticorrosive properties for aluminium alloy in 0.5 M HCl by using potentiodynamic polarization (PDP), gravimetric weight loss, and Electrochemical impedance spectroscopic (EIS) methods. The corrosion inhibition characteristics of ELE on aluminium in HCl solution have been examined. This investigation showed the finest inhibition efficiencies of 95.0%, 92.0% and 89.3% that were obtained from weight loss, PDP and EIS at concentration of 0.5% ELE at 303 K respectively. As per Langmuir adsorption isotherm models, an extract of Eucalyptus leaves was adsorbed on the metal surface. The effect of the temperature on the corrosion behaviour with adding of the best concentration of ELE was studied in the temperature range 313–333 K. It was found that inhibition efficiency is independent of temperature. The negative Gibb's free energy and activation parameters of the ELE were recorded and the results indicated that the adsorption rates were spontaneous. The results obtained from PDP and EIS shows that the corrosion inhibition procedure is charge transfer controlled, and the ELE works as a mixed-type inhibitor. The findings of SEM (Scanning electron microscopy) and AFM (Atomic forcemicroscopy) studies support the adsorption inhibition mechanism. The results of all the experiments conduct are consistent. The functional groups of the ELE were identified using Fourier transform infrared (FTIR) spectroscopy.

Electrochemical and molecular modelling studies of corrosion inhibition characteristics of imidazolines on 1Cr steel under sweet conditions

ABSTRACT Organic compounds like imidazoline derivatives are commonly used as corrosion inhibitors. This study characterised the corrosion inhibition properties of two forms of imidazoline, 2-Methyl-2-imidazoline (2-MI) and 2-Phenyl-2-imidazoline (2-PI), with and without the presence of mono ethylene glycol (MEG) on steel surface under CO2 corrosion condition. Electrochemical, surface characterisation and molecular modelling were used to study corrosion inhibition properties and underlying mechanisms. In the pure form, 2-PI had higher corrosion inhibition efficiency than 2-MI, likely due to stronger adsorption to the steel surface, as confirmed by molecular modelling. The addition of MEG improved the inhibitor efficiency of both 2-MI and 2-PI.

A synthesized pyrimidine derivative with highly efficient long-term corrosion protection for API X60 steel in CO2-saturated NACE brine ID196 under hydrodynamic condition

This research investigates the CO2 corrosion inhibition characteristics of a synthesized pyrimidine derivative whose molecular structure is embellished with nitrogen-based functional groups with the intention of achieving highly effective and stable film formation, at low doses, after prolonged corrosion period under turbulent hydrodynamics. For this purpose, 5-(4-(dimethylamino)phenyl)-2,7-dithioxo-2,3,5,6,7,8-hexahydropyrimido[4,5-d]pyrimidin-4(1H)-one (DPP) was synthesized using the one-pot method, and investigated as inhibitor against the corrosion of API X60 steel after instantaneous and prolonged (72 h) immersion in CO2-saturated NACE ID196 brine under 1000 rpm rotation speed. Results from potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) measurements show that DPP is a mixed-type inhibitor which lowers the double layer capacitance and rate of charge transfer across the steel-solution interface with 97% efficiency. Its instantaneous adsorption blocks the steel surface from any noticeable microstructural damage, based on scanning electron microscopy (SEM) characterization. After prolonged exposure (72 h), the uninhibited steel experiences enhanced resistance, which inversely depreciated the DPP efficiency to > 73%. With DPP, however, the steel is significantly protected against surface microstructural degradation, based on SEM assessment. Computational modeling with density functional theory (DFT) and molecular dynamics simulation (MDS) provided molecular-level confirmation of the experimental results.

Revealing the Correlation between Molecular Structure and Corrosion Inhibition Characteristics of N-Heterocycles in Terms of Substituent Groups

Controlling metal corrosion can directly address the waste of metal and the environmental pollution and resource depletion caused by metal recycling, very significant factors for green and sustainable development. The addition of corrosion inhibitors is a relatively cost-effective means of corrosion prevention. Among these, N-heterocycles have been widely used because heteroatoms contain lone pairs of electrons that can be strongly adsorbed onto metals, protecting them in highly corrosive environments at relatively low concentrations. However, due to the large variety of N-heterocycles, their corrosion inhibition characteristics have seldom been compared; therefore, the selection of appropriate N-heterocycles in the development of anti-corrosion products for specific applications was very difficult. This review systematically analyzed the influence of different substituents on the corrosion inhibition performance of N-heterocycles, including different alkyl chain substituents, electron-donating and electron-withdrawing substituents, and halogen atoms, respectively. The correlation between the molecular structure and corrosion inhibition characteristics of N-heterocycles was comprehensively revealed, and their action mechanism was analyzed deeply. In addition, the toxicity and biodegradability of N-heterocycles was briefly discussed. This study has provided a significant guideline for the development of green, promising corrosion inhibitors for advanced manufacturing and clean energy equipment protection.

Assessment of the inhibitive performance of a hydrazone derivative for steel rebar in a simulated concrete medium: Establishing the inhibition mechanism at an experimental and theoretical level

In the present work, a low-cost and practical approach based on an eco-friendly corrosion inhibitor is suggested for protecting steel rebar. To this end, a new hydrazone derivative, namely N'-(furan-2-ylmethylene)-2-(5-methoxy-2-methyl-1H-indol-3-yl) acetohydrazide (FMAH) was synthesized and its corrosion inhibition characteristics for steel rebar (STR) in chloride contaminated simulated concrete pore solutions (ClSCPS) were evaluated using experimental and theoretical methods. The electrochemical studies, which were conducted at several periods ranging from 1 h to 30 d indicated that the addition of FMAH to the ClSCPS significantly improved the passive film formation. It considerably increased film and charge transfer resistances at an early immersion stage, then decreased at longer immersion periods. Potentiodynamic polarization curves (PPCs) revealed that the investigated compound could be categorized as a mixed inhibitor with a predominance anodic effect. The gravimetric and potentiodynamic polarization studies confirmed corrosion inhibition efficiencies of 80.9% and 81.1%, respectively, for 1.0 mmol.L-1 FMAH after 30 d of exposure. Surface characterization of corroded and inhibited STR surface by X-ray photoelectron spectroscopy (XPS), SEM coupled with EDS, Raman spectroscopy, atomic force microscopy (AFM) and X-ray diffraction spectroscopy (XRD) revealed that inhibitor molecules chemically adsorbed on the STR forming a highly resistant protective layer against corrosive species. Theoretical modeling of inhibitor’s adsorption on the iron surface by the self-consistent-charge Density-functional tight-binding (SCC-DFTB) indicated the formation of several covalent bonds between carbon and oxygen atoms with the iron atoms. The analysis of FMAH-Fe (110) adsorption systems by projected density of states revealed that FMAH molecules adsorbed on the iron surface through a charge transfer process. The interesting results from the present work would open great opportunities for exploring the anti-corrosion performance of the investigated compound in concrete.

Soybean extract firstly used as a green corrosion inhibitor with high efficacy and yield for carbon steel in acidic medium

The soybean extract (SE) was firstly investigated for corrosion inhibition characteristics on carbon steel in sulfuric medium. The weight loss and electrochemical methods were used to research the inhibition performance and adsorption properties of SE in combination with halide ions. Results showed the SE + I - inhibitors possessed outstanding corrosion inhibition efficiency, ~98%. Furthermore, the effective compound of SE was identified to be responsible for the corrosion inhibition effect. The AFM , water contact angle and XPS measurements confirm the formation of a corrosion inhibitor film on carbon steel. Combining differential capacitance curves, corrosion inhibition mechanism was further interpreted. Good inhibition efficiency, green extract solvent, facile extraction procedure, high yield and environment sustainability, endow SE as novel corrosion inhibitor with a promising future for industrial application. ● Soybean extract (SE) was firstly utilized as an eco-friendly, promising corrosion inhibitor. ● SE exhibited excellent inhibition efficiency (~98%) in combination with I - for carbon steel in sulfuric solution. ● Characteristic adsorption of I - would make for protonated SE adsorption on positively charged carbon steel surface.

Evaluation of corrosion inhibition characteristics of an N-propionanilide derivative for mild steel in 1 M HCl: Gravimetrical and computational studies

Evaluation of corrosion inhibition characteristics of an N-propionanilide derivative for mild steel in 1 M HCl: Gravimetrical and computational studies

Influence of positive pulse voltages on structure, mechanical, and corrosion inhibition characteristics of Si/DLC coatings

In this study, Si/DLC films were effectively deposited on 2024-Al alloy using a plasma-enhanced chemical vapor method at different pulse voltages. Scanning electron microscopy, X-ray diffraction spectroscopy, 2D optical profilometer, Raman spectroscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy were used to characterize the structure of the DLC coatings. The adhesion strength was performed using Scratch Tester. Further, the Nano Indenter G200 apparatus was used to measure the hardness and Young's modulus of coatings. The Ball-on-Disk Tester was used to measure the friction coefficient of the specimens. A Potentiostat/Galvanostat electrochemical workstation was used to examine the corrosion performance and passive stability of DLC coatings in 3.5 wt% NaCl solution. The findings demonstrated that the thickness of the coatings increased with increasing the pulse voltage to 1800 V, causing an improvement in mechanical properties and corrosion resistance. This is due to an increase in the amount of sp3 hybrid in the coating, which reduces the electrical conductivity of DLC and limits electron transfer and electrical charge exchange at the coating surface. However, the corrosion rate of the coatings increased when the pulse voltage increased to 2200 V.

Novel cationic aryl bithiophene/terthiophene derivatives as corrosion inhibitors by chemical, electrochemical and surface investigations

Two novel bithienyl fluorobenzamidine derivatives namely, 4-([2,2′:5′,2′′-terthiophen]-5-yl)-2-fluorobenzamidine hydrochloride salt (MA-1615), 5′-(4-amidino-3-fluorophenyl)-[2,2′-bithiophene]-5-carboxamidine dihydrochloride salt (MA-1740) were synthesized, characterized and their corrosion inhibition properties were evaluated by electrochemical methods for carbon steel (C-steel) in 1 M HCl. Experimental investigations revealed that the inhibition effectiveness of the investigated inhibitors (INHs) by the Tafel polarization method followed the order: MA-1740 (96.9%) > MA-1615 (95.6%), demonstrating higher efficiency than inhibitors of similar structure reported in the literature. The investigated bithiophene derivatives exhibit mixed-type corrosion inhibition characteristics by blocking the active sites on the surface of C-steel. EIS study revealed that the INHs behave as interface-type corrosion inhibitors. UV–Visible spectrometric measurements confirmed a complex formation between the Fe2+ cation released during the corrosion reactions and inhibitor molecules.