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Seawater, which has been frequently applied in cooling and injection water systems, imposes severe pitting corrosion to mild steel. Addition of green and sustainable inhibitors based on renewable sources is one of the promising methodologies for restricting metal corrosion in chloride-containing electrolytes. In this study, for the first time, from both theoretical and experimental faces, the role of Juglans regia green fruit shell (JRS) extract as a sustainable potent corrosion inhibitor for mild steel was studied. The chemical structure of the JRS extract was deliberated by Fourier transform infrared spectroscopy (FT-IR). By electrochemical techniques including polarization, EIS and electrochemical current noise analyses, the corrosion inhibition performance of 1000 ppm JRS extract in the saline solution was examined. The surface characterization of the plates after 24 h immersion in the saline solution was done applying ATR-FTIR and FE-SEM-EDS analyses. The polarization test results illustrated that in the attendance of 1000 ppm JRS extract, both of cathodic and anodic reactions rates were noticeably retarded. Also, the corrosion inhibition efficiency of the mild steel plates reached ~ 94% in presence of 1000 ppm JRS extract. EIS results revealed that in the attendance of the JRS extract and with the immersion time progress up to 48 h, the inhibition capacity of inhibitor was promoted. The theoretical investigation results revealed the efficient adsorption of the organic components existed in the JRS extract on the surface of plates constructing a corrosion protecting barrier film.

Combining silane formulation with appropriate non-toxic chrome-free corrosion inhibitors provides high performance coatings with superior anti-corrosion properties. The aim of this work is development of an environmentally friendly sol-gel based silane coating with smart self-healing corrosion resistance properties utilizing the mixture of organic-benzimidazole/inorganic-praseodymium inhibitors. Results of electrochemical impedance spectroscopy (EIS), electrochemical noise (EN), scanning vibrating electrode technique (SVET), potentiodynamic polarization, and salt spray tests declared the effective self-healing characteristics of the coating incorporated with the mixture of inhibitors. The healing capability of the modified coatings was demonstrated by SVET. The current distribution results indicated that both anodic and cathodic inhibition occur at the scratched area with a dominant effect on the cathodic zones.

The Persian Liquorice was introduced as a sustainable corrosion inhibitor with excellent inhibition action for mild steel in sodium chloride solution. Persian Liquorice is a root of Glycyrrhiza glabra including many active compounds like Glycyrrhizin (GL), 18β- Glycyrrhetinic acid (GA), Liquritigenin (LTG), Licochalcone A (LCA), Licochalcone E (LCE), and Glabridin (GLD). The Fourier transform infrared (FT-IR) spectroscopy was utilized to track various active components exist in the Persian Liquorice extract. Electrochemical impedance spectroscopy, potentiodynamic polarization and electrochemical current noise measurements were conducted to investigate the corrosion inhibition role of various concentrations of Persian Liquorice extract toward mild steel corrosion in sodium chloride solutions. Surface analysis, molecular dynamics and quantum mechanics simulation methods were combined to get insights of inhibitor molecules adsorption on the mild steel surface. The electrochemical investigations revealed that in the presence of 600 ppm Persian Liquorice extract the maximum inhibition efficiency of 98.8% was obtained, which is connected to the build-up of a protecting layer over the mild steel surface, blocking the pathway of harsh ions diffusion. There is no report on use of any sustainable corrosion inhibitor for mild steel in chloride solution with this high level of inhibition power even after long immersion time (72 h). The formation of protecting layer on the mild steel surface was proved by scanning electron microscope and atomic force microscope results. The results derived from MD simulations and QM calculations revealed the adsorption of Persian Liquorice components on the steel substrate via donor-acceptor interactions.

International audience; The objective of this study was to develop multifunctional protective biocompatible (Cu, Zr)/a-C: H coatings with good mechanical properties and high corrosion resistance using a sputtering system on the surface of TC4 alloy. Coatings with a higher Zr/Cu ratio showed higher hardness, Young's modulus, and superior bio-corrosion resistance. It was demonstrated that charge transfer resistance of the coating with a higher Zr/Cu ratio enhanced from ∼40 kΩ. cm2 to ∼990 kΩ. cm2 after 168 h of immersion time. The results also showed strong synergistic effects of Cu and Zr, as well as the formation of the zirconium carbide phase on the surface.

This study aims at studying the effect of silane hydrolysis time and concentration on the corrosion protection performance of an eco-friendly hybrid silane coating based on tetraethylorthosilicate (TEOS) and trimethoxymethylsilane (TMOMS) on mild steel substrate. By electrochemical impedance spectroscopy (EIS) and salt spray test the corrosion evaluations were done. Results of Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA) and water contact angle tests measurements revealed the effective impact of the hydrolysis time and silane concentration on the curing process of the coating. Results revealed that the mixture of 50% silanes (TEOS/ TMOMS: 50/50 w/w) hydrolyzed for 24 h resulted in the highest corrosion resistance. The enhancement in protective performance of the hybrid coating was connected to the better condensation reaction, denser Si–O–Si network formation and less hydrophilicity of the coating.

Progress in tissue engineering and regenerative medicine necessitates the use of novel materials with promising bio-surface for biomedical applications. In this work, TixNy thin films are applied on biological TC4 substrates in a mixed atmosphere of Ar and N2 via magnetron sputtering system for the protection of TC4 alloy. The effects of N/Ti ratio on the phase structure, growth orientation, contact angle, and the mechanical and corrosion performances of thin films are discussed by implementation of composition-microstructure-property interrelationships. The phase structure of TixNy thin films is changed from amorphous-like to single phase Ti2N structure with increasing N/Ti ratio. In the same direction, the growth orientation changed from (112) to (200). The contact angle of TC4 alloy increased by applying TixNy thin films on the substrate. TixNy thin films prepared at higher N/Ti ratios resulted in higher contact angle, mechanical properties, corrosion resistance and biocompatibility. The hardness value of the films varied between 7.5 to 28 GPa, while the Young’s modulus, EIT, of the films ranged from 152 to 476 GPa. The maximum protection efficiency in SBF solution was found to be about 99.4%. Based on equivalent circuit model of MG63 cell, the TiN-4 exhibited the nearest similarity with best biocompatibility. The results of this work uncovered the critical roles of nitrogen content and growth orientation on the mechanical and biological properties of TixNy thin films. The upshots illuminate the appropriate properties of such system, which can be potentially used in different application such as metal orthopedic and neural electrodes. Development of such surface-coated titanium alloy showing superior corrosion resistance and biocompatibility can pave the way towards advanced bio-coatings with multifaceted features.

The corrosion inhibition mechanism of mild steel in acidic solution and in the presence of two cationic gemini surfactants have been studied. These are two surfactants having 12-carbon hydrophobic tails: one with a tetramethylene spacer and the other one with the same spacer containing two hydroxyl groups. EIS and polarization and electrochemical noise measurements revealed superior corrosion inhibition of hydroxyl functional surfactant compared with its counterpart with no hydroxyl group. Surface analysis including AFM, and SEM confirmed less corrosion attacks on the sample exposed to hydroxyl functional surfactant solution. Quantum chemical parameters revealed a good correlation with electrochemical results.

The objective of this study is to investigate the inhibition of Glycyrrhiza glabra extract, commonly known as licorice, as a green source of corrosion inhibitor against mild steel corrosion in 1 M HCl solution. The extract of Glycyrrhiza glabra has been used for mild steel inhibition in 1 M HCl solution. By means of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) the corrosion inhibition performance and by atomic force microscopy (AFM) and contact angle test the surface characteristics were evaluated. The results of polarization test revealed that the Glycyrrhiza glabra leaves extract acted as mixed type inhibitor and retarded both anodic and cathodic reactions rates. Results revealed that by addition of Glycyrrhiza glabra leaves extract the corrosion current density of mild steel significantly decreased from 260 μA/cm2 for the sample without inhibitor to 40.2 μA/cm2 for the sample containing 800 ppm inhibitor. In addition, it was found that in the presence of Glycyrrhiza glabra leaves extract the hydrogen evolution mechanism did not change but the anodic dissolution mechanism of iron was affected in the presence of inhibitors. The EIS results showed that the increase of Glycyrrhiza glabra leaves extract concentration and immersion time resulted in the increase of corrosion inhibition efficiency. The maximum corrosion inhibition efficiency (about 88%) and surface coverage (about 72%) were obtained in the presence of 800 ppm Glycyrrhiza glabra leaves extract after 24 h immersion. Atomic force microscopy test results showed lower mild steel surface degradation in the HCl solution with 800 ppm Glycyrrhiza glabra leaves extract. Also, the decrease in surface hydrophilicity in the presence of Glycyrrhiza glabra leaves extract confirmed the adsorption of organic molecules of the inhibitors, such as Glycyrrhizin (GL), 18β-Glycyrrhetinic acid (GA), Liquritigenin (LTG), Licochalcone A (LCA), Licochalcone E (LCE), and Glabridin (GLD), on the active sites of mild steel. In addition, the modeling studies based on classical molecular dynamics (MD), Monte Carlo (MC) and quantum mechanics (QM) techniques evidenced that all corrosion inhibiting materials exist in Glycyrrhiza glabra adsorbed to steel surface, and thereby form a corrosion-protective film over the steel surface.

In this study an epoxy-ester coating was filled with zinc acetyl acetonate (ZnAA). The active corrosion inhibition properties of the ZnAA pigment were studied by electrochemical noise (EN), electrochemical impedance spectroscopy (EIS) and polarization techniques. Also, the surface morphology and composition of the steel panels were examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The electrochemical measurements revealed the effective corrosion inhibition properties of the ZnAA pigment in the solution phase. Polarization test results revealed that in the presence of ZnAA both cathodic and anodic current densities decreased. In fact, the Zn2+ cations and acetyl acetonate anions formed inhibitive films based on Fe2+-acetyl acetonate and zinc oxide/hydroxide complexes on the anodic and cathodic regions. Results of theoretical ab initio quantum mechanics and molecular dynamics simulations evidenced that the inhibitors strongly adsorbed to iron surface through donor–acceptor interactions. The EIS results showed that the epoxy-ester coating protection performance was significantly enhanced by addition of ZnAA hybrid pigment. The ZnAA pigment enhanced the barrier performance of the coating and provided active inhibition properties.

A hybrid corrosion inhibitive pigment based on zinc cation-basil leaf extract was synthesized for application in protective construction coatings. Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS), UV–vis spectroscopy, and thermal gravimetric analysis (TGA) were used for characterization of the hybrid pigment. Electrochemical impedance spectroscopy (EIS) was utilized to evaluate the corrosion inhibition efficiency of the hybrid pigment in 3.5 wt% NaCl solution on mild steel. The protective functioning of the synthesized pigment as incorporated into the epoxy coating was studied via salt spray test and EIS. Results showed a significant corrosion inhibition by the hybrid pigment in the solution phase. Besides, the hybrid pigment provided considerable improvement in corrosion protection in intact and artificially scratched coatings.

The application of corrosion inhibitors on metallic surfaces is sorely vital for increased longevity with lessened maintenance costs. In this paper, Cynara scolymus L extract was tested as a green/bio-degradable corrosion inhibitor for mild steel in sodium chloride solution by using electrochemical techniques. Hence, the ultraviolet-visible spectrophotometry (UV–Vis) and Fourier transform infrared (FT-IR) spectroscopy were conducted for Cynara scolymus L extract characterization. The electrochemical results indicated that the values of corrosion current density and double-layer capacitance decreased as time increased. The polarization results revealed that the nature of Cynara scolymus L adsorption is mixed with dominantly anodic. The results also suggest that the inhibition power is 96.1% at 1000 ppm in the sodium chloride solution. The corrosion inhibiting action of the Cynara scolymus L is ascribed to the process prohibition due to the surface film formation over the mild steel surface. The computer modeling (including molecular dynamics (MD), density functional theory including dispersion corrections (DFT-D), and Monte Carlo (MC)) achievements further supported the adsorption of Cynara scolymus L molecules on the mild steel surface. Furthermore, the DFT-D calculations suggested the adsorption of the inhibitor via electronic donor-acceptor interactions. As a result, the Cynara scolymus L is a practical green/bio-degradable inhibitor that helps to tailor the corrosion obstacles of mild steel for injection water and cooling systems.

This work intends to study the effect of a polydimethylsiloxane additive on the protection performance of a hybrid silane coating on mild steel. Electrochemical impedance spectroscopy, polarization and electrochemical noise measurements and salt spray showed an increase in corrosion resistance of the silane coating in the presence of the additive. Silane films were examined by FTIR, water droplet contact angle, Vickers hardness and SEM. Results showed decrease in crosslinking density in the presence of the additive. Superior corrosion protection in the presence of additive was attributed to the enhanced hydrophobic character and flexibility of the coating.

Mg-Al-PO 4 3− layered double hydroxide (LDH) nanoparticle was synthesized through an anion exchange method and characterized by XRD, IR spectroscopy and SEM. The phosphate and Mg 2+ release ability of Mg-Al-PO 4 3− LDH in the 3.5 wt. % NaCl solution was measured by inductively coupled plasma-optical emission spectrometer (ICP-OES). Results showed the release of Mg 2+ from the LDH scaffold along with phosphate anion from LDH gallery, illustrating importance of solubility rather than ion-exchange mechanism. Then, the corrosion inhibitive behavior of Mg-Al-PO 4 3− LDH in 3.5 wt. % NaCl solution was assessed by electrochemical measurements and FE-SEM in comparison with the Mg-Al-NO 3 − LDH. The results showed that Mg-Al-PO 4 3− LDH forms inhibitive film on the mild steel and significantly mitigate corrosion compared to Mg-Al-NO 3 − LDH. The LDHs were also employed in a silane primer top-coated by epoxy-polyamide on mild steel. The results of electrochemical measurements showed significant active corrosion protection ability of Mg-Al-PO 4 3− LDH in the coating with an artificial defect. Furthermore, the adhesion strength of the coating including Mg-Al-PO 4 3− LDH to mild steel after exposure to salt spray (5% NaCl solution) was improved.

This study aims at synthesis and characterization of Zn-Al-PO 4 3− and Zn-Al-NO 3 − layered double hydroxides (LDHs) through employing FE-SEM, EDS and X-ray photoelectron spectroscopy (XPS) analyses. The smart release ability of the inhibitive spices from LDHs were checked by EIS, polarization and surface analysis tests in 3.5 wt.% NaCl solution. A two-layer coating system consisting of silane primer filled with LDHs and epoxy-polyamide top coat were applied on steel and then the active inhibition capability of the coatings was investigated. The addition of Zn-Al-PO 4 3− LDH to the silane coating provides efficient inhibition behavior by releasing PO 4 3− anions through ion exchange process.

Regarding the favorable advantages of green inhibitors, there are a number of studies to introduce the inhibition behavior of this type of material to enhance the protection of metals. In the present study, the mild steel substrates are protected in the acidic process by Artichoke as a green corrosion inhibitor. Some professional measurements were chosen for the corrosion inhibitive action evaluation of the Artichoke at various concentrations in the acidic solution. The electrochemical outcomes implied that the Artichoke revealed a superior inhibition action to mild steel. It was demonstrated that the charge transfer resistance of the Artichoke with a higher concentration (1000 ppm) enhanced from ~9.9 Ω. cm2 to ~795.2 Ω. cm2 after 24 h of immersion. The maximum corrosion inhibition efficiency (about 98.7%) and surface coverage (about 76.3%) were obtained in the presence of 1000 ppm Artichoke extract after 24 h immersion. The polarization results also revealed that by the addition of Artichoke extract, the corrosion current density of the mild steel significantly decreased from 6.3 μA/cm2 for the sample without inhibitor to 0.1 μA/cm2 for the sample containing 1000 ppm inhibitor. The Artichoke could effectively protect the steel through physicochemical interaction and film formation to mitigate the serious demolition of cl−. This green corrosion inhibitor is applicable to work out the corrosion obstacles of metallic equipment in the acidic process. Also, the adsorption of anticorrosive chemicals on the substrate was computationally ascertained by molecular/DFT (density functional theory) modelings

The energetic bombardment of a growing coating with energetic particles is an efficient strategy for tailoring the structure and properties of a protective coating for a specific application. Applying the pulsed substrate bias voltage (PSBV) on the metal substrate is a recently developed technique with the aim of the energetic bombardment of a growing coating. Amorphous-Carbon: Niobium (a-C: Nb) thin layers were applied on GTD-450 stainless steel substrates at various PSBV. Coatings microstructures, mechanical characteristics, coefficient of friction (COF), and corrosion protection ability of the deposited substrates were studied. The outcomes of XRD investigation certified the establishment of face-centered cubic (fcc), Nb-C phase, and the dominant orientation of the structure transformed from {1 1 1} into {2 2 0} as the PSBV increases. The outcomes from Raman spectroscopy showed a higher proportion of sp2 hybridization Carbon is formed inside the structure of the coatings, which was prepared under lower PSBV. On the contrary, a higher percentage of sp3 hybridization Carbon is developed under higher PSBV. Coatings internal stress, hardness, and plasticity index also increase as the bias voltage increases. Moreover, the pulsed biased coatings showed higher hardness compared to non-biased coating. The COF of (a-C: Nb) thin coatings demonstrated a non-linear correlation in a way that raised by increasing the PSBV to −100 V and then reduced as the PSBV decreased. Electrochemical impedance spectroscopy evaluation demonstrated that significant enhancement in corrosion protection of (a-C: Nb) thin coating is obtained as PSBV gets higher and immersion time prolongs. As a result, the PSBV is a promising deposition parameter that helps to tailor mechanical and electrochemical properties of GTD-450 alloy for a specific application.

In this work, graphene oxide (GO) based nano-platforms were applied as a non-hazardous solid container with high encapsulating capacity and controllable release activity of eco-friendly inhibitor. For the first time, the adsorption and release properties of the praseodymium cations (Pr3+) on GO nanosheets functionalized with polyaniline (PANI) were investigated. The Pr3+ cations adsorption/desorption capacity of GOPANI nano-sheets was assessed by Inductively Coupled Plasma (ICP), X-ray photoelectron spectroscopy (XPS), Field Emission Scanning Electron Microscopy (FE-SEM), and High-resolution transmission electron microscopy (HR-TEM) techniques. The obtained results proved that the container modified with Pr3+ cations at pH of 7, 600 ppm of adsorpt, and 1 mg/cc of adsorbent dosage provided the highest capacity of inhibitors adsorption/release rates. The adsorption capacity of the GO-PANIs reached more than 500 mg/g. Also, the modified carrier desorbed about 70 % of loaded Pr3+ cations in the corrosion simulated condition. The self-healing anti-corrosion ability of the constructed containers in an organic-inorganic hybrid coating (OIHC) was shown by electrochemical analyses results. The resistance of coating with the loaded carriers has increased about 1 order of magnitude in comparison with the neat silane. Moreover, the scratched coatings containing the inhibitor loaded GO-PANIs showed extraordinary total resistance of about 25 Kohm. cm2.

Graphite like Carbon: Niobium (GLC:Nb) thin films with different Nb contents were applied on GTD-450 stainless steel substrates. The microstructure, mechanical properties, friction coefficient and anti-corrosion performance of the coatings were investigated. The outcomes from Raman spectroscopy confirmed the formation of GLC phase. The results from X-ray diffraction (XRD) analysis also endorsed the formation of face center cubic Nb-C phase and by increasing the Nb content, the grain size of this phase increased. The hardness of the coating increased with increasing the Nb content, reaching to the value of ~12 GPa for Nb content of ~50 at% (N-4). On the contrary, the friction coefficient of the coated substrates decreased by increasing the Nb content. Electrochemical impedance spectroscopy (EIS) measurements depicted a remarkable improvement in the corrosion resistance of the GTD-450 stainless steel substrate coated by GLC:Nb. Altogether, considering the outstanding mechanical and anti-corrosion properties of the coated steel, the GLC:Nb coating can be propounded as an auspicious candidate to be applicable as a heavy-duty protective coating for the metal substrate which is used in harsh environments such as turbine blades.

High performance double-layer coatings composed of copper (Cu) interlayer and the Cu/diamond-like carbon (DLC) composite top layer were prepared via magnetron sputtering for protection of carbon steel. The effect of Cu content in the composite layer on the internal stress, contact angle, mechanical, tribological, and corrosion performance of coatings was discussed. Raman spectroscopy confirmed formation of DLC phase. Double-layer Cu-rich coatings exhibited high degree of sp2 carbon clustering, but low diamond-like sp3 bonding. The internal stress of double layer Cu-(Cu/DLC composite) coatings was decreased with Cu content increase. The double-layer Cu-(Cu/DLC composite) thin films with low Cu content did not pose a significant effect on hardness and Young's modulus of the steel substrate, while increase of Cu content enhanced hardness of coating up to 28 GPa. The contact angle of steel substrate showed an increase when coated with double-layer Cu-(Cu/DLC composite) thin film, but not that much at such inadequate Cu content. Inclusion of Cu interlayer improved to some extent corrosion properties, where increase of Cu content assisted in protection. Double-layer coatings with the highest performance were compared with single-layer Cu/DLC coating. Elimination of interlayer deteriorated mechanical properties, but increased electrochemical performance, signifying the importance of controlling Cu/DLC composition and Cu interlayer inclusion.

In this paper, the influence of sol–gel surface modification of lithium zinc phosphate (LZP) pigment by methacryloxy propyl trimethoxy silane on corrosion inhibition, dispersion stability and adhesion strength was studied. IR spectroscopy and thermogravimetric analysis confirmed that organic functional group was successfully grafted onto the LZP surface. EIS and polarization measurements of mild steel showed an improvement in corrosion resistance for the extract of surface modified pigment in 3.5 % NaCl solution which was connected to better solubility proved by ICP-OES. The dispersion stability of the pigment in epoxy resin was found to be improved after surface modification. In addition, the adhesion strength of the epoxy coating containing surface modified pigment to mild steel after exposure to salt spray (5 % NaCl solution) was enhanced. The sol–gel surface modification had led to increase in hydrophobicity of the pigment particle surface, but simultaneously increased solubility of the pigment in water possibly due to the lower degree of agglomerates or aggregates of the pigment particles.

A sodium zinc phosphate pigment synthesized using a co-precipitation method and characterized by X-ray diffraction was investigated for its corrosion inhibition activity in comparison with the commercial zinc phosphate using EIS in a 3.5% NaCl solution. A mild steel surface analysis after exposure to the test solutions was conducted using scanning electron microscope-energy dispersive X-ray and infrared spectroscopies. The results indicate that the corrosion inhibitive performance of the synthesized pigment is higher than that of the commercial zinc phosphate. This can be the result of the synthesized pigment's relatively high solubility, which affects the precipitation of a phosphate layer onto the mild steel surface and the modification of the crystalline structure of the corrosion products in the presence of the inhibitive pigment. The salt spray and wet pull-off tensile strength results revealed an improved corrosion protection of the coatings formulated with SZP.

Lithium zinc phosphate (LZP) has been synthesized through a co-precipitation process and characterized by XRD and IR spectroscopy. The inhibitive performances of this pigment for corrosion of mild steel have been discussed in comparison with the zinc phosphate (ZP) in the pigment extract solution by means of EIS and in the epoxy coating by means of salt spray. The EIS and salt spray results revealed the superior corrosion inhibitive effect of LZP compared to ZP. Moreover, adhesion strength and dispersion stability of the pigmented epoxy coating showed the advantage of LZP compared to ZP.

The synthesis condition of potassium zinc phosphate pigment was optimized with respect to corrosion inhibition in extract solution and dispersion stability in an epoxy resin by application of Taguchi experimental design. Processing parameters, including calcinations time, quiescent time, mixing rate and KOH/ZnCl 2 mole ratio are selected as the influential parameters. Corrosion inhibition of the pigments in the extract solutions and dispersion stability in the epoxy resin were evaluated by electrochemical impedance spectroscopy (EIS) and turbidity measurement, respectively. The pigment synthesized under optimal condition was characterized by XRD, which showed formation of KZnPO 4 and KZn 2 PO 4 (HPO 4 ). Corrosion protection of the epoxy coating containing synthesized pigment at optimal condition was evaluated by salt spray and compared to the unpigmented epoxy coating. Salt spray results showed higher corrosion protection of the epoxy coating in the presence of potassium zinc phosphate, which could be attributed to lower diffusivity of the pigmented coating to Cl − or formation of phosphate layer confirmed by SEM–EDX.