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Abstract Erosion–corrosion of 6061 aluminum alloy was attenuated with a green inhibitor Boswellia serrata (BWS) under submerged jet impingement condition by using artificial seawater slurry. Erosion–corrosion rates in the absence and in the presence of inhibitor were achieved by potentiodynamic polarization techniques (PDP). Experiments were performed under the varying concentration of inhibitor at different flow rates and temperatures. Conditions were optimized to obtain maximum inhibition efficiency. Mechanistic aspects of the corrosion and inhibition process were studied in detail by the electrochemical impedance spectroscopy (EIS) technique by correlating the data with appropriate equivalent circuit models. Adsorption of inhibitor was confirmed by surface morphology studies using scanning electron microscopy technique (SEM). Suitable mechanism was proposed for corrosion inhibition process. The inhibition efficiency increased with an increase in its concentration and it decreased with an increase in the flow rate and temperature. The inhibition efficiency of 70% was obtained for 1000 ppm of inhibitor at 303 K at the flow rate of 4 L min−1. It was proved that the mechanism of corrosion inhibition under this tribological condition is charge transfer controlled. The effect of hydrodynamics on the inhibitor efficiency of Boswellia serrata extract was remarkable. Boswellia serrata emerged as an efficient green inhibitor of erosion–corrosion control of 6061 aluminum alloy under submerged jet impingement conditions. Graphical abstract

Results of anticorrosive performance of ionic liquid 1-methyl-1-propyl-piperidinium bromide (MPPB) on corrosion of 6061Al-10vol% SiC composite (Al-MMC) in 0.05 M HCl solution. Electrochemical techniques were adopted to study corrosion and corrosion inhibition rates. Experiments were conducted in the temperature range of 308–323 K by varying concentrations of MPPB. Conditions were standardized to accomplish maximum inhibition efficiency. Kinetic parameters were evaluated. Results were fitted into various adsorption isotherm models and they fitted best into the Langmuir adsorption isotherm. Using data from adsorption isotherms, thermodynamic parameters were calculated. The surface morphology was examined by energy-dispersive X-ray spectroscopy (EDAX), atomic force microscope (AFM), and scanning electron microscope (SEM). FTIR–spectra and X-ray diffraction (XRD) studies were performed to reaffirm the adsorption of MPPB. Adsorption of the inhibitor and mechanistic aspects of corrosion inhibition were supported and supplemented by quantum chemical calculations using density functional theory (DFT). The investigation revealed that percentage inhibition efficiency (% IE) improved with the increase in the concentration of MPPB, while it decreased with a rise in temperature. Maximum efficiency of 60% was observed with 400 ppm MPPB at 308 K. MPPB acted as a mixed inhibitor, obeyed the Langmuir adsorption model, and the mode of adsorption was physisorption. Quantum chemical calculations validated the results of the adsorption study. Graphical abstract

Anticorrosive coatings are extensively used to protect metals and alloys, especially in the marine environment. This study reports the enhancement of coating performance of epoxy primer coating on zinc in 3.5% NaCl at 303 K by impregnating the epoxy primer with micro and nano particulates of biopolymers. Initially, conditions were standardized to achieve optimum efficiency of Maltodextrin (MLD) and Glycogen (GLY) for corrosion of zinc in 3.5% NaCl. The optimum concentration of inhibitors was then added to the epoxy primer coating a applied on zinc. Anti-corrosion performance of epoxy primer with biopolymer was compared with that of standard coating, which was devoid of biopolymers. The coating characteristics were further enhanced by incorporating nanoparticles of MLD and GLY into the epoxy primer matrix. Potentiodynamic polarization measurement (PDP) and Electrochemical impedance spectroscopy (EIS) were employed to study corrosion rate measurement. Detailed surface morphology was studied using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) techniques. Electrochemical and surface studies clearly demonstrated the capability of micro and nanosized biopolymers in improving the anti-corrosion performance of the coating. The average efficiency of epoxy primer coating improved to a considerable extent by studying biopolymers. The overall efficiency of the coating formulation was found to be 99.5%. Surface morphology studies showed that coating thickness increased to 32.1 µm from 27.2 µm after incorporating biopolymers. In addition to this, there was a remarkable change in the surface roughness of epoxy primer coating in contact with 3.5% NaCl after the addition of biopolymers into it. The coating formulation developed turned out to be eco-friendly with significant environmental benefits.

The fouling behavior of Alloy 6061 aluminum in artificial seawater in the presence of Boswellia serrata extract was investigated. Fouling is one of the major issues that occurred commonly in the marine environment. Experiments were conducted to develop a model for fouling propensity. A response surface method was used to develop a model to predict fouling behavior. The model predicts the effect of the variables on fouling in artificial seawater medium in the presence of B. serrata extract. The experimental variables chosen were temperature, flow rate and time. Performance of the regression model calculated by the response surface methodology was verified with the analysis of variance technique. The model equation that was proposed using the response surface methodology showed good agreement with the experimentally obtained data.

The present study reports a sustainable source of lignin, from termite frass. Lignin was extracted using Klason’s method and subjected to polarization studies to check the inhibition efficiency and measured the electrochemical performance of the coated sample on the carbon steel using electrochemical impedance spectroscopy. The anticorrosive property was determined in a simulated corrosive environment (0.1 M NaOH and 0.5 M NaOH). The morphological analysis of the surface of both bare metal and the lignin-coated ones, before and after exposure to the corrosive environment, was recorded using atomic force microscopy (AFM), scanning electron microscopy (SEM), and energy-dispersive X-Ray spectroscopy (EDX). The lignin showed maximum inhibition efficiency at 600 ppm in 0.5 M NaOH solution. Moreover, the lignin coated on carbon steel exhibited about 70% corrosion inhibition efficiency as recorded by potentiodynamic polarization studies and electrochemical impedance spectroscopy. The AFM and SEM analyses further corroborated the protection of the metal surface from corrosion when coated with lignin. Hence, the study suggests lignin from termite frass as a sustainable biological source suitable for anticorrosive applications. Graphic abstract

Biological macromolecules are proven to be potential green corrosion inhibitors because of their outstanding structural features and eco-friendliness. This study is aimed at enhancing their corrosion mitigation capabilities by converting them into nanoparticles. This is the first work where nanoparticles of biological macromolecules are exploited for corrosion mitigation studies. Glycogen nanoparticles (GLY-Np) were synthesized by microwave�mediated nanoprecipitation method and characterized by ATR–FTIR, XRD, UV–Visible Spectroscopy, FESEM analysis, EDX, TEM, and Zeta potential measurements. They are used as an eco-friendly inhibitor for corrosion control of zinc in sulfamic acid (NH2SO3H). The electrochemical study was a primary experimental tool employed for corrosion rate measurement. Conditions were optimized to obtain maximum inhibition efficiency by varying concentrations of inhibitor and temperature. Activation and thermodynamic parameters were eval�uated and discussed in detail. A suitable adsorption isotherm was proposed to fit the experimental results. Adsorption of the inhibitor was confirmed by SEM, EDX, and AFM techniques. The inhibition efficiency of 92% was obtained for 0.02 gL− 1 GLY-Np. Thus, GLY-Np turned out to be an effective green inhibition with economic benefits

The study aimed to assess the alterations in the morphology, elemental composition, and biocompatibility of infra-zygomatic crest (IZC) miniscrews, before and after their insertion in the patient’s oral cavity. The study was conducted on 16 IZC miniscrews (8 as-received and 8 retrieved). Scanning electron microscopy (SEM) was used to evaluate the miniscrew surfaces. Micrographs were obtained at ×50, ×100, and ×500 magnification. The miniscrews were subjected to Energy-dispersive x-ray (EDX) analysis to investigate the elemental composition. It was performed at four zones of each miniscrew- head, neck, body, tip. Corrosion of the miniscrews was analyzed through the potentiodynamic polarization (PDP) test by immersing the stainless steel (SS) miniscrews in an artificial saliva medium (pH 5.8) and then allowing it to obtain a steady-state open-circuit potential (OCP) for 15 min. Gingival fibroblasts were cultured using gingival tissue which was used to check the biocompatibility of the miniscrews by observing their proliferation and viability by MTT colorimetric assay. The SEM analysis showed generalized surface dullness, variable corrosion, craters, and blunting in the retrieved miniscrews. EDX analyses showed the deposition of additional elements: carbon, oxygen, calcium, and nitrogen in the retrieved miniscrews. PDP tests showed a higher corrosion rate in the retrieved miniscrews, but the results were not significant. The MTT assay showed that the cell viability was higher in the as-received group and the results were statistically significant with apvalue of 0.002. It was concluded that the retrieved miniscrews exhibited morphologic surface changes in the form of dullness, blunting of threads and tips, corrosion, craters, and cracks which were not seen in the as-received miniscrews. A higher percentage of adsorbed elements were seen on the retrieved miniscrew surface. The corrosion rate assessed through the PDP test for both groups was comparable. The fibroblast cell viability was significantly reduced in the retrieved miniscrews when compared to as-received miniscrews.

Benzyl isothiocyanate (BITC) was used as anticorrosive agent for the corrosion mitigation of stainless steel in 0.5 M hydrochloric acid medium. The corrosion inhibition study of (BITC) was investigated by potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) techniques in the temperature range of 303–323 K. The study was done to get optimum inhibition efficiency. The surface morphology was studied using scanning electron microscopy (SEM). Elemental mapping was done by energy dispersive X-ray (EDX) studies. Suitable mechanism was proposed for corrosion and inhibition process. Quantum chemical calculations were done and discussed in detail using density functional theory (DFT). Maximum inhibition efficiency of 86% was achieved for the addition of 0.025 g L−1 of the inhibitor at 308 K. BITC acted as mixed inhibitor and obeyed Langmuir adsorption. Surface morphology studies reaffirmed the adsorption of BITC onto the surface of steel. Quantum chemical calculations supported experimental observations.

An eco-friendly green corrosion inhibitor Commiphora Mukul was tested for its efficacy to control material loss in 6061 aluminum alloy under collective influence of mechanical erosion and electrochemical corrosion in a submerged jet impingement rig. Electrochemical techniques were utilized in the current investigation which consisted of potentiodynamic polarization and electrochemical impedance spectroscopy. The effect of temperature and flowrate of artificial seawater slurry on the inhibitory effect of Commiphora Mukul is investigated. Under the experimental conditions of 303 K temperature and 4 L min−1 flowrate, the inhibitor showed an efficiency of 54% as determined by the potentiodynamic polarization studies. With the increase in temperature and flowrate of artificial seawater slurry, the protection efficiency of the inhibitor decreased. Protection efficiency of 35% was observed. Possible reasons for this phenomenon were discussed. Electrochemical impedance studies reported that the process is both charge transfer and diffusion controlled. At 323 K, the diffusion component was prominent for all the studied flowrates of 4 L min−1, 8 L min−1, and 12 L min−1. It seems that the moving medium makes it challenging for the inhibitor molecules to adsorb on the metal surface in the presence of abrasive particles.

The objective of the work is to introduce and establish anticorrosion capabilities of a novel biopolymer glycogen (GLY) against sulfamic acid (NH2SO3H) induced corrosion of zinc. The corrosion and inhibition studies were done by electrochemical techniques such as potentiodynamic polarization (PDP) measurements and electrochemical impedance spectroscopy technique (EIS). Conditions were optimized to get maximum inhibition efficiency by varying the concentration of the inhibitor in the temperature range of 303–323 K. Activation and thermodynamic parameters were evaluated and discussed in detail. Suitable adsorption isotherm was proposed to fit the experimental results. Scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and atomic force microscopy (AFM) studies were performed before and after the addition of inhibitor. Adsorption of inhibitor was further confirmed by UV–Visible spectroscopy. Quantum chemical calculations were done to establish the correlation between the structure of the inhibitor and its inhibition efficiency. Energy of HOMO, LUMO, energy gap ∆E, dipole moment (µ) Mullikan charges were calculated. Different theoretical factor descriptors like the hardness (η), and softness (σ) electronegativity (χ), global electrophilicity (ω), nucleophilicity (ε) and fraction of electron transferred (ΔN) were calculated. Inhibition efficiency of glycogen increased with increase in its concentration and with temperature. Maximum efficiency of 72% could be achieved for the addition of 0.05 g L−1 of GLY at 323 K. Results were fitted into Langmuir adsorption iostherm. The surface of the metal turned visibly smoother in the presence of GLY. In addition the EDX studies showed increase in carbon content which re-affirmed the adsorption of GLY on the metal surface. The density functional theory (DFT) based theoretical studies supported the experimental observations.

This study focuses on investigating the effect of Terminalia chebula Ritz. extract (TCE) for corrosion inhibition of Al in phosphoric acid (H3PO4) using potentiodynamic polarization (PDP) technique. In this study, the effect of concentration of TCE extract, the concentration of H3PO4 acid medium, and temperature (T) was investigated on the corrosion current density (icorr) and inhibition efficiency (IE). The TCE was characterized by FTIR analysis, and the adsorption of TCE was justified with the help of kinetic, thermodynamic, adsorption isotherm parameters. The surface morphology study was done using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDXS), and atomic force microscopy (AFM). The study also focuses on identifying the optimum process parameters for obtaining the maximum IE by applying the response surface methodology (RSM) and desirability function approach. The maximum IE of 83.24% was achieved at a temperature of 30 ℃, the concentration of TCE extract of 500 ppm, and H3PO4 acid concentration of 0.5 M. Regression analysis, Pareto chart, normal chart, main effect, and interaction effect plots are employed to acquire an in-depth understanding of process variables on IE. The IE obtained from the experiments and the predicted model is in a close match and a high value of the coefficient of determination (R2 = 99.98%) displays that the generated model was able to estimate the IE accurately from the selected process variables.

The studies on corrosion control of 6061Al–15%(V) SiC(P) composite (AlMMCs) in 0.025 M HCl have been carried out by employing electrochemical techniques like potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) using biopolymer pectin as inhibitor. Pectin showed increase in the inhibition efficiency, when the concentration of it was increased from 0.2 to 1.0 g L−1. Inhibition efficiency also increased with increasing the temperature of corrosive medium from 303 to 323 K. The thermodynamic and kinetic calculations showed that pectin underwent chemisorption by following Langmuir adsorption isotherm. Surface morphology studies were carried using scanning electron microscopy (SEM), and it was supported by elemental analysis performed by using energy-dispersive x-ray (EDX) analysis technique. Suitable mechanism was proposed for the corrosion inhibition process. Maximum inhibition efficiency of 95% was observed for the addition of 1 g L−1 of pectin. Pectin emerged as an excellent green corrosion inhibitor for the corrosion control of AlMMCs in acid medium, with environment benefits.

Erosion corrosion performance of 6061 aluminum alloy in simulated sea water slurry was investigated under multi-phase jet impingement conditions. The main objective of the work is to study erosion–corrosion of a material with engineering application and mitigate it using eco- friendly green inhibitor. Experiments were performed with the sand concentration of 0.3% and 0.3 μm size. The effect of temperature and flow rate on the performance of inhibitor was explored. Electrochemical methods were adopted for erosion-corrosion measurements. Experiments revealed that starch could mitigate erosion-corrosion with a maximum reduction efficiency of 58% at temperature of 303 K and flow rate of 4 L·min–1 . Inhibition efficiency decreased with increase in flowrate and temperature. EIS spectrum demonstrated that the corrosion process in the presence on inhibitor was both charge transfer and mass transfer controlled. A key role of hydrodynamics in the performance of corrosion inhibitor was confirmed by the present study.

The present work highlights the results of the application of a green inhibitor for material conservation. The anticorrosive performance of the pectin bio-polymer was established for the corrosion control of mild steel in a 1 M phosphoric acid medium. Electrochemical measurements such as potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) studies were adopted for the corrosion inhibition studies. The studies were carried out by varying the concentrations of pectin in the temperature range from 303 K to 318 K. Conditions were optimized to get maximum inhibition efficiency. The surface morphology study was done by scanning electron microscope (SEM), and elemental mapping was done using energy dispersive X-ray (EDX) studies to confirm the adsorption and interaction of the inhibitor with the material. Studies showed an increase in the inhibition efficiency with an increase in the concentration of pectin and also in the temperature. Maximum inhibition efficiency of 70% was achieved by the addition of 800 ppm of inhibitor. Pectin acted as a mixed type inhibitor by bringing down both cathodic and anodic reactions. Kinetic and thermodynamic parameters revealed chemical adsorption of pectin onto the mild steel surface. A suitable mechanism was proposed for the adsorption of pectin which was reaffirmed by the surface morphology studies. Pectin emerged as a potential eco-friendly green inhibitor for the corrosion control of mild steel, with economic benefits.

Zinc, an important nonferrous metal, is the fourth most used metal in the world. It has innumerable uses in industrial as well as in other segments. The primary utility of zinc is in galvanization and as an anode in the battery. Steel coated with zinc, which is known as galvanized steel, is widely used in industries. Even though zinc protects many metals from undergoing corrosion, by itself, it undergoes corrosion in several acidic, alkaline, and neutral environments. The corrosion behavior of zinc is significant in all industries where it is utilized either directly or indirectly in the form of a sacrificial coating. In-depth analysis of the reported literature indicated that corrosion attenuation of zinc in acidic and alkaline medium was studied by many researchers, and various classes of inhibitors were tried under varying experimental conditions. Most inhibitors can be amalgamated as excellent inhibitors with an inhibition efficiency of 80–90%. Even though this is a subject of intense research, systematic documentation on the same is not available in the literature. This review consolidates research work on corrosion and inhibition studies of zinc and galvanized steel over a period of three decades.

Fouling is known to be a prominent industrial problem which is greatly affected by parameters like temperature, time and flowrate. The aim of this work was to simulate the fouling process in AA 606...

The work highlights the utility of biopolymer blend as an effective corrosion inhibitor and proves its ability to improve the coating characteristics of epoxy resin on steel during acid corrosion. Biopolymer blend of starch and pectin was prepared and characterized by viscosity measurements and spectral studies. Initially conditions were optimized to get maximum inhibition efficiency of biopolymer blend for the acid corrosion control of steel. Electrochemical techniques such as potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) were adopted for the corrosion rate measurements. Later, same techniques were employed to study the corrosion rate of the epoxy resin coated steel before and after the addition of environmentally benign biopolymer blend. Detailed investigation of surface morphology of epoxy coated steel was carried out using scanning electron microscopy (SEM), energy dispersion X-ray (EDX) and X-Ray Diffraction (XRD) techniques

The liquid-solid erosion-corrosion behavior of aluminum in artificial seawater medium at open circuit has been investigated using a submerged jet impingement rig. The aluminum alloy 6061 coupons subjected to erosion corrosion condition were placed normal to the impinging jet. The gap maintained between the nozzle and the specimen was 5mm. In the present study, sea sand was used as an erodent. Erosion corrosion rate was measured using potentiodynamic polarization and electrochemical impedance spectroscopy methods. At a flowrate of 4 lpm passivation was observed in the potentiodynamic polarization plot which was confirmed by the appearance of inductive loop in the Nyquist plot. At higher flowrates no such condition was observed. The system response to impedance studies was characterized by a high frequency capacitive loop and a capacitive loop at the lower frequency. Surface morphology was studied with scanning electron microscopy (semi quantitative analysis) and atomic force microscopy techniques. Elemental mapping was done with electron dispersive X-ray studies. The erosion-corrosion rate increased with increase in the flow rate and temperature. The results of this work will aid in the selection of material for controlled or reduced material loss in sea water circulating equipment’ and pipelines.

Maltodextrin (MLD) is introduced as a novel, potent green inhibitor for the corrosion control of zinc in 0.1 sulfamic acid. The corrosion and inhibition studies were done by electrochemical techniques such as potentiodynamic polarisation measurements and electrochemical impedance spectroscopy technique. Conditions were optimised to get maximum inhibition efficiency by varying the concentration of the inhibitor in the temperature range of 303–323 K. Activation and thermodynamic parameters were evaluated and discussed in detail. Suitable mechanism was proposed for corrosion and inhibition process. Surface characterisation was done by SEM, EDX and AFM techniques before and after the addition of inhibitor. The density functional theory calculations were performed and compared with experimental observations. Results indicated that inhibition efficiency increased with the temperature and inhibitor concentration. Maximum inhibition efficiency was found to be 62.3% for the addition of 0.4 g L−1 MLD. Theoretical calculations confirmed the experimental observations.

The work highlights the results of application of green inhibitor biopolymer glycogen for the corrosion mitigation of 6061 aluminum alloy in 0.01 N sulfuric acid medium. The corrosion rate measurements were done by electrochemical methods like electrochemical impedance spectroscopy and potentio-dynamic polarization techniques. Conditions were optimized to get maximum inhibition efficiency by varying the concentration of the inhibitor in the temperature range of 308–318 K. Kinetic and thermodynamic parameters were evaluated and discussed in detail. Results were fitted into an appropriate adsorption isotherm. Suitable mechanism was proposed for corrosion and inhibition studies. Surface characterization was performed before and after the addition of inhibitor using SEM–EDX and AFM techniques. Inhibitor underwent physical adsorption onto the metal surface and obeyed Langmuir adsorption isotherm. Surface studies confirmed the adsorption of inhibitor onto the metal surface, and according to AFM studies, surface had become remarkably smooth after the addition of inhibitor. Results obtained by potentio-dynamic polarization and impedance studies were in very good agreement with each other. Glycogen emerged as potential green inhibitor for the corrosion control of 6061 aluminum alloy in 0.01 N sulfuric acid medium with a maximum efficiency of 54.73% at 308 K for the addition of 0.8 g L−1 Work is a contribution to corrosion chemistry using eco-friendly biopolymer as green inhibitor.

This work emphasizes the corrosion inhibition ability of pullulan, an environmentally benign fungal polysaccharide on acid corrosion of 6061Aluminum-15%(v) SiC(P) composite material (Al-CM). The electrochemical measurements such as potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) studies were carried out for the corrosion inhibition studies. Conditions were optimized to obtain maximum inhibition efficiency, by performing the experiment at varying concentrations of inhibitor, in the temperature range of 308K- 323K. Surface morphology studies were done to reaffirm the adsorption of inhibitor on the surface of composite material. Pullulan acted as mixed type of inhibitor with a maximum efficiency of 89% at 303K for the addition of 1.0 gL-1 of inhibitor. Evaluation of kinetic and thermodynamic parameters revealed that inhibitor underwent physical adsorption onto the surface of Al-CM and obeyed Freundlich adsorption isotherm. The surface characterization like SEM-EDX, AFM confirmed the adsorption of pullulan molecule. Pullulan can be considered as effective, eco friendly green inhibitor for the corrosion control of Al-CM.

Work undertaken introduces environmentally safe inhibitor to attenuate acid corrosion of Al-CM. Studies were done by PDP and EIS techniques. Conditions were optimized to get maximum inhibition efficiency. Kinetic and thermodynamic parameters were calculated and discussed in detail. SEM, EDX, AFM, XRD and FT-IR techniques were adopted for surface morphology studies. Inulin showed maximum inhibition efficiency of 90% at 303 K. It acted as mixed type of inhibitor, underwent physisorption and followed Langmuir adsorption isotherm. The remarkable surface smoothness of Al-CM was achieved due to adsorption on inhibitor. The work is a contribution to corrosion chemistry using eco-friendly inhibitor.

Pectin (PECT), a carbohydrate polymer, is presented as an active, environmentally benign inhibitor to attenuate the 6061 aluminium alloy acid corrosion. The study was performed by adopting electrochemical and spectroscopic procedures. Surface studies were performed by scanning electron microscopy (SEM), energy dispersion X-ray studies (EDX), and atomic force microscopic (AFM) technique. Mode of adsorption of PECT on the surface of the alloy was arrived at by applying appropriate adsorption isotherm, which is further confirmed spectral studies like FT-IR and UV–visible spectroscopy. Adsorption of PECT was reiterated by quantum chemical calculations using density functional theory (DFT). Pectin emerged as a potent green inhibitor with an inhibition efficiency of around 80% for the addition of 800 ppm of it. DFT calculations contributed a deeper insight in systematic understanding of the mechanism of the corrosion inhibition process.

In recent years, application of nanoparticles in various fields of physical science and natural science receiving tremendous attention from researchers. Nanoparticles can offer significant advantages in terms of high stability, enhanced mechanical properties, and high surface area to volume ratio. This work attempts to explore these noble characteristic properties of nanoparticles for preservation for materials of engineering applications. Nanoparticles of maltodextrin (MLD-Np) were prepared by microwave-mediated nanoprecipitation technique. Characterization was done by spectral, zeta potential measurement, X-ray studies, Scanning Electron Microscope (SEM) and Transmission Electron Microscopy (TEM) analysis. In the second part, these nanoparticles were tested for their surface protection ability due to interfacial adsorption. Corrosion inhibition study measurements were done by electrochemical methods, and interfacial adsorption of inhibitor was established by studying surface morphology. The efficacy of these nanoparticles was 93% for the addition of 50 ppm of it. In the last part of this work, an attempt is made to compare the inhibiting ability of various reported chemical inhibitors for acid corrosion of zinc with synthesized nanoparticles. Nanoparticles of maltodextrin emerged as an appreciably good green corrosion inhibitor with environmental and economic benefits.

Environmentally benign biopolymer dextran was used to control the corrosion of 6061 Al alloy in 1 M HCl. The electrochemical techniques employed for the studies were potentiodynamic polarization and electrochemical impedance spectroscopy. The surface morphology was studied by scanning electron microscopy and elemental mapping was done by the energy dispersive X-ray analysis. Dextran emerged as a potential green corrosion inhibitor for the corrosion control of 6061 Al alloy in an acidic medium. It acted as mixed inhibitor, underwent physisorption and followed the Langmuir adsorption isotherm.

The corrosion behavior of aluminum in the hydrochloric acid medium of pH 3 was studied usingTafel polarization and electrochemical impedance spectroscopy techniques in the presence or the absence ofthe Murraya koenigii (commonly known as curry) leaves extract at 303 K to 323 K. The concentration of theinhibitor used was in a range of 0.05–0.4 gL−1. The inhibition efficiency was found to increase with increasingthe inhibitor concentration and decreasing temperature. Polarization data showed that the curry leavesextract (CLE) acted as anodic type of inhibitor at lower concentrations of the inhibitor and as mixed type athigher concentrations of the inhibitor. The maximal inhibition efficiency of 91.79% was obtained with the CLE at its optimum concentration of 0.4 gL−1. Adsorption of the CLE was found to obey the Langmuiradsorption isotherm and underwent both physisorption and chemisorption process. The kinetic and thermodynamicparameters were calculated and discussed in detail. The results obtained by both methods were ingood agreement with each other. The protective film formed on the surface of aluminum by the adsorption of inhibitor molecules present in the CLE in the hydrochloric acid medium of pH 3 was confirmed by the scanning electron microscopy and energy-dispersive X-ray spectroscopy. So, the CLE emerged as a potential, cost-effective and eco-friendly natural inhibitor for the corrosion control of aluminum in the hydrochloric acid medium.

The acid corrosion control of 6061Aluminum alloy and 6061Al-15%(v) SiC(P) composite material (Al-CM) was carried by using inulin - a carbohydrate polymer as a green inhibitor. Potentiodynamic polarization (PDP) and Electrochemical Impedance Spectroscopy (EIS) techniques were adopted. Concentration of inulin was in the range of 0.2gL-1-1.0gL-1, and studies were done in the temperature range of 303-323K. The adsorption of inhibitor on the surface of Al alloy and Al-CM was confirmed by physical techniques such as Scanning electron microscopy (SEM), energy-dispersive X-Ray analysis (EDX), and atomic force microscopy (AFM) analysis. The studies showed that inhibition efficiency of inhibitor increased with increase in concentrations of inulin and decreased with increase in temperature. The adsorption of inulin on metal surface obeyed Langmuir adsorption isotherm through physical adsorption on both alloy and on Al-CM. Results obtained from potentiodynamic polarization method and electrochemical impedance spectroscopic methods were in good agreement with one another.

Protection against corrosion using Sinapis alba was studied for the corrosion control of stainless steel in 0.5 M HCl. The electrochemical techniques such as potentiodynamic polarization measurements and electrochemical impedance spectroscopy were used for the stainless steel protection studies. Surface morphology studies were done using scanning electron microscopy/energy dispersive X-ray analysis. Kinetic and thermodynamic parameters were evaluated and discussed. The mechanism for the corrosion inhibition was proposed. The obtained results showed that Sinapis alba acted as a mixed-type inhibitor, with the maximum inhibition efficiency of 88% for the concentration of 0.1 g L–1 at 323K. It was chemically adsorbed on stainless steel and obeyed the Langmuir adsorption isotherm. Sinapis alba emerged as an effective eco-friendly corrosion inhibitor for the corrosion control of stainless steel in the HCl acid medium. Surface morphology studies confirmed the adsorption of this inhibitor onto the surface of the metal. The results obtained via potentiodynamic polarisation and electrochemical impedance spectroscopy was in agreement with each other.

Corrosion inhibition characteristics of bio polymer dextran was studied for the corrosion control of 6061 Al-15% (v) SiC (p) composite and its base alloy in 1 mol·L − 1 HCl. Standard electrochemical techniques such as potentiodynamic polarization (PDP) measurements and electrochemical impedance spectroscopy (EIS) method were adopted for corrosion rate measurement. Surface morphology was studied by scanning electron microscopy (SEM) and elemental mapping was done by energy dispersive X-ray (EDX) analysis. Suitable mechanism was proposed for corrosion and inhibition process. Results indicated that dextran acts as an excellent anticorrosive agent for the corrosion control of 6061 Al-15% (v) SiC (p) composite, with maximum inhibition efficiency of 91% for the concentration of 0.4 g·L − 1 at 303 K. Dextran acted as a mixed type of inhibitor, and got physically adsorbed both on composite and base alloy by obeying Langmuir adsorption isotherm. Dextran is proved to be a green inhibitor with environmental and economic benefits.

This work describes the use of polymer dextran to enhance the corrosion protection of epoxy coating applied on 6061 Al-15%(v) SiC(p) composite material (Al-CM). Initially, conditions were established to obtain optimum inhibition efficiency of dextran. Electrochemical techniques such as potentiodynamic polarization and electrochemical impedance spectroscopy were adopted for the corrosion rate measurements. Later, the same techniques were employed to study the corrosion rate of the epoxy resin coated composite material (EC-CM) before and after the addition of environmentally benign dextran polymer. Detailed investigation of the surface morphology of the coated Al-CM was carried out using scanning electron microscopy, energy dispersion X-ray analysis, and atomic force microscopy techniques. The work which is done with dual purpose, establishes not only the anticorrosive property of dextran, but also proves its ability to improve the coating characteristics of epoxy resin on Al-CM.

Deterioration of metals in the form of corrosion is the major problem faced in almost all industries. Annual cost of corrosion world-wide has been estimated to exceed 3% of world’s GDP. Corrosion control of metals is an activity of economic, environmental, aesthetic, and technical importance. Zinc, one of the most important non-ferrous metals, has a wide range of applications in industry as well as in domestic sectors. It is used as a coating material on steel and iron. Corrosion of zinc and galvanized articles can be prevented by using chemical inhibitors. Even though they are proven to be effective for industrial applications, environmental hazards resulted as a consequence cannot be ignored. Over the last decades, research is more focussed towards the use of environmental friendly green inhibitors. In this regard, plant extracts have become important as an environmentally acceptable, readily available, and renewable source for a wide range of inhibitors. This review consolidates and documents an overview of the application of plant products as corrosion inhibitors for the corrosion mitigation of zinc.