Corrosion Prevention Strategies Research Articles

Experimental and theoretical simulations to examine the influence of nonionic surfactant on the corrosion control of mild steel in hydrochloric acid

The increasing demand for corrosion prevention strategies that are both effective and sustainable is part of the research the background. Nonionic surfactants offer a potential replacement for traditional corrosion inhibitors. These surfactants are well-known for their low toxicity and biodegradability. The research involved conducting experimental tests (such as weight loss, polarization and impedance spectroscopy) and theoretical computations to investigate the role of nonionic surfactant (polyoxyethylene (7) tribenzyl phenyl ether) (PETPE) in controlling the corrosion of mild steel in hydrochloric acid (1.0 M HCl) environment. The results of the study demonstrated that PETPE exhibited significant corrosion inhibition properties for mild steel in HCl solution. The inhibition efficiency of PETPE was found to increase with increasing PETPE concentration. PETPE is an excellent corrosion inhibitor because it significantly reduces the rate of corrosion, as seen by the notable inhibition efficiency result (95.4%) at a relatively low dose of PETPE (100 ppm). Thermodynamic studies were used to discuss the fundamental mechanisms that control PETPE-acid interactions. The adsorption process followed Langmuir adsorption isotherm, indicating a monolayer adsorption of the PETPE on the mild surface. Theoretical computations confirm the strong inhibition behavior of PETPE. The innovative feature of this research is its comprehensive strategy, which integrates experimental studies and theoretical simulations to evaluate the impact of PETPE on the corrosion control of mild steel in hydrochloric acid. The combined effort has the ability to supply valuable knowledge into the mechanisms of corrosion that will lead to the establishment of powerful corrosion control strategies.

In-depth assessment of new coumarin derivative based on azo dye and Schiff base as an effective corrosion inhibitor for steel in 1 M HCl solution and anti sulphate reducing bacteria: Insights from computational and experimental techniques

This paper examines the innovative application of PAEOD as a corrosion suppressant for steel in an acidic environment with a concentration of 1.0 M HCl. The inhibitory potential of PAEOD has been comprehensively evaluated through the utilization of diverse analytical approaches, including electrochemical tests, gravimetric analysis, and scanning electron microscopy (SEM) assessments. The results suggest that there is a correlation between concentration and the enhancement of corrosion resistance, hence categorizing PAEOD as a mixed-type inhibitor. The maximum inhibitory efficiency was observed at a concentration of 7.50 × 10-4 M, resulting in a remarkable efficiency of 98.84 % at a temperature of 298 K. The electrochemical investigation demonstrated a significant rise in the values of charge transfer resistance (Rct) and polarization resistance (Rp), accompanied by a reduction in the Constant Phase Element (CPE.Yo) value to 74.01 μF. These findings suggest an improved capacity for inhibiting corrosion. Theoretical studies have revealed a significant interaction between PAEOD and the steel surface, as evidenced by the utilization of density functional theory (DFT) and Monte Carlo/ Molecular dynamic (MC/MD) techniques. This interaction indicates the presence of exceptional anti-corrosion properties at the micro-level. The impact of PAEOD on the growth of sulphate reducing bacteria (SRB) was found to be substantial, as indicated by the findings derived from BART™ Vials. In summary, this work establishes PAEOD as a potentially effective corrosion inhibitor, offering significant contributions to the field of corrosion prevention strategies through its important insights.

Semi-Quantitative Categorization Method for the Corrosion Behavior of Metals Based on Immersion Test

Corrosion processes are complex in nature and their studies have become an interdisciplinary research field, combining fundamental sciences and engineering. As the quantification of corrosion processes is affected by many variables, standard guidelines to study such phenomena had been developed, such as ASME and ISO, and are broadly used in industry and academics. They describe methods to perform immersion test experiments and to quantify the corrosion rates of metals exposed to corrosive environments, but do not provide any guidelines for post-exposure analysis of the as-obtained corroded samples, which might provide useful information to understand the underlying physicochemical mechanisms of corrosion. This knowledge is useful for selecting optimal construction materials and developing corrosion prevention strategies. In this work, a semi-quantitative categorization method of the corrosion behavior of metals exposed to a corrosive medium based on their mass loss and aspect is presented. For each category, the mathematical aspects of gravimetric measurements of mass change rate and the analytical techniques that can be used for the characterization of materials are discussed. The following method does not intend to replace industrial standards, but to expand them in order to maximize the amount of information that can be extracted from immersion tests.

Mechanistic insights into the corrosion inhibition of mild steel by eco-benign Asphodelus Tenuifolius aerial extract in acidic environment: Electrochemical and computational analysis

This study explores the novel application of Asphodelus Tenuifolius aerial extract (ATAE) as a corrosion inhibitor for mild steel in a 0.5 M HCl acidic environment. By utilizing techniques such as electrochemical measurements, gravimetric analysis, SEM, and CA assessments, the inhibitory potential of ATAE has been comprehensively evaluated. The results revealed a concentration-dependent enhancement in corrosion resistance, classifying ATAE as a mixed-type inhibitor by measuring the anodic (βa) and cathodic (βc) polarization slope values of 108.89 and −129.33 mV/dec. The peak inhibition efficiency was observed at 250 ppm, reaching an impressive IE% of 94.40 % at 298 K (Kelvin). The electrochemical analysis demonstrated a significant increase in charge transfer resistance (Rct) and polarization resistance (Rp) values, coupled with a decrease in Constant Phase Element (CPE.Yo) value to 162.94 μF, indicating heightened corrosion inhibition potential. Additionally, Theoretical calculations emphasized a strong interaction between ATAE and mild steel surface, characterized by a low energy gap (ΔE), indicating excellent anti-corrosion abilities at the micro-level. This study positions ATAE as a promising corrosion inhibitor, offering insights for further research in corrosion prevention strategies using a sustainable corrosion inhibitor.

Corrosion Inhibition of Mild Steel in HCl Solution Using MPO: Experimental and Theoretical Insights

Corrosion is a pervasive challenge in various industrial applications, particularly in acidic environments. This comprehensive study delves into the effectiveness of 2-methyl-4-propyl-1,3-oxathiane (MPO) as a corrosion inhibitor for mild steel exposed to hydrochloric acid (HCl) solutions. The investigation employs weight loss techniques to assess the inhibitor's performance over varying durations (ranging from 1 to 48 hours) and concentrations (0.1 to 1 mM). At a concentration of 0.5 mM, the inhibitor demonstrates impressive inhibitory efficiency, ranging from 87.6% at 303 K to 92.9% at 333 K during a 5-hour exposure period. Additionally, the impact of temperature on the corrosion inhibition process is examined at temperatures of 303, 313, 323, and 333 K, showing substantial inhibition efficiencies. Quantum chemical calculations using Density Functional Theory (DFT) methods elucidate the molecular interactions between MPO and the metal surface. Notably, the analysis of EHOMO (Highest Occupied Molecular Orbital Energy), ELUMO (Lowest Unoccupied Molecular Orbital Energy), Egap (Energy Gap), total hardness (η), electronegativity (χ), and electron fraction transition atom (ΔN) reveals valuable insights into MPO's corrosion inhibition capabilities. The outcomes underscore MPO's potential as an effective corrosion inhibitor for mild steel in HCl environments, laying the groundwork for more efficient corrosion prevention strategies in industrial settings.

Influence of Sulfate and Iron Reducing Bacteria on Carbon Steel Corrosion in Marine Environments

The current study highlights the corrosion consequences observed in API 5L X65 carbon steel when exposed to a marine-like environment containing carbon dioxide (CO2), in the presence of sulfate- reducing bacteria consortium (C-SRB), iron-reducing bacteria consortium (C-IRB), and a combination of both (C-SRB+C-IRB). The corrosion behaviour was assessed through the utilisation of weight loss and surface analysis techniques. The biofilms and corrosion products were characterised using field emission scanning electron microscopy (FESEM) and infinite focus microscope (IFM), respectively. The results obtained from the weight loss technique provided confirmation that in the absence of bacteria, uniform corrosion was the prevailing mechanism in the medium. The uniform corrosion rate was found to be 0.95 mm/year, which was higher than the pit penetration rate of 0.28 mm/year. The combined actions of the C-SRB+C-IRB consortium result in a synergistic impact, leading to a significantly higher rate of pit penetration compared to the individual activities of SRB. Specifically, the pit penetration rate value of 2.13 mm/year is observed, which is notably higher than the uniform corrosion rate of 0.59 mm/year. The utilisation of surface analysis techniques has shown evidence of the existence of sulfur on carbon steel samples that were subjected to exposure from the C-SRB+C-IRB consortium in a CO2 environment. This sulphur presence is believed to potentially play a role in the development of the iron sulphide (FeS) layer. FeS presence is a contributing factor to the occurrence of pit corrosion due to the SRB metabolite activities. The activities of these metabolites readily dissolve in the medium, hence altering the chemical interface properties of both the metal and the biofilm. For specimens exposed to C-SRB only, the results obtained were almost identical to exposure to the C- SRB+C-IRB consortium. However, the corrosion rate value measured for the C-SRB+C-IRB consortium was higher due to the synergistic effect of the two bacteria. In conclusion, the presence of C-SRB alone and the consortium of C-SRB+C-IRB in a CO2 environment induces the formation of pitting corrosion. The findings of this study are presumed to contribute a deep understanding of the microbiology-influenced corrosion (MIC) mechanism in CO2 environments troubling the oil and gas industry. With a better understanding of MIC, new and improved corrosion prevention strategies can be put into action.

(Corrosion Division Morris Cohen Graduate Student Award) Evolution of Passivity and Passivity-Breakdown for Cr and Cr-Containing Alloys

Among several corrosion prevention strategies for metallic alloys, alloying with so-called ‘passivating’ elements remains the most effective approach. For example, chromium (Cr) remains the key functional alloying element for Fe-based stainless steels, Ni-based Inconel® alloys and Co-based Stellite® alloys, which dominate the family of corrosion resistant alloys (CRAs) used in a wide range of applications. In addition to conventional alloys, recent exploration in the materials community has led to development of an emerging class of alloys, so-called high entropy alloys (known more broadly as multi-principal element alloys (MPEAs)), which contain multiple alloying elements in ‘principal’ fractions – and of which the corrosion performance has not been widely studied to date. It is however challenging to ascertain the key controlling factors responsible for the passivity in MPEAs using conventional electrochemical techniques due to the combination of low sensitivity and the lack of element resolved information. Moreover, the physical and chemical properties of the nano-metric thin passive film upon CRAs are challenging to evaluate using conventional microscopy and spectroscopy. Consequently, several fundamental aspects of passivity of Cr-containing CRAs remain open questions to be elucidated.The work herein sought to investigate the passivity and dissolution of Cr and Cr-containing alloys, including stainless steel and several MPEAs; primarily using an in-situ electrochemical method called atomic-spectroelectrochemistry (ASEC). ASEC uses a modified flow electrochemical cell coupled with an atomic spectrometer, revealing the real-time and element-resolved dissolution rate during electrochemical testing. In addition to ASEC analysis, the project herein employed a range of electrochemical testing, electron microscopy, X-ray photoelectron spectroscopy, and thermodynamic calculations to explore Cr-based passivity.Significance between composition and growth kinetics on the passivity of Cr and Cr-containing alloys was established. It was found that the passive films upon Cr and Cr-containing alloys (including MPEAs) obey a direct-logarithmic growth law, consistent with the assumptions of the point defect model. In addition, the results unveiled a complex interdependence of oxidation rate of material and dissolution rate of the passive film during anodic polarization, found to be an important parameter to evaluate barrier properties of passive films. The influence of microstructural features including grain boundaries and chemical heterogeneities on Cr-based passivity was explored for stainless steel 316L; whereas the role of alloying elements and electrolytic on the evolution of compositional morphology and thickness of the Cr2O3-based passive film was studied for MPEAs exhibiting single-phase microstructures. The origin of passive film breakdown and role of potential and chloride ions on the breakdown mechanism were elucidated for stainless steel 316L; whereas transpassive dissolution and origin of secondary passivation were studied for equiatomic CoCrFeNi and AlTiVCr MPEAs.Such insights advance the knowledge of underlying mechanisms and associated rate controlling factors of passivity in Cr and Cr-containing alloys, aiding towards an ‘oxide-by-design’ paradigm, to guide design of new CRAs.

Gravimetric and electrochemical investigation of the impact of various factors on XC48 carbon steel corrosion in different environments

ur main motivation in this study was to review the effects of acid concentration and solution temperature on the corrosion behavior of XC48 carbon steel in acidic and saline environments. We conducted both gravimetric and electrochemical analyses to evaluate the extent of corrosion. The gravimetric study revealed interesting findings regarding the influence of acid concentration on the corrosion rate. Initially, as the acid concentration increased, the corrosion rate showed an upward trend, reaching a peak at approximately 6M (44.1%) of sulfuric acid. However, at higher concentrations, such as 10.3M (65.15%) the corrosion rate decreased to a lower value at different immersion times. A similar trend was observed with phosphoric acid, where the maximum corrosion rate occurred at around 10M (66.6%), but decreased at 14.5M (84.68%) over different immersion times. Notably, in the case of hydrochloric acid, the corrosion rate exhibited a logarithmic behavior at higher concentrations (6M, 7M, 10M), which can be attributed to the formation of passive layers. The decrease in corrosion rate at higher concentrations indicates the protective effect of these passive layers. During the electrochemical analysis, we investigated the effect of temperature and NaCl concentration on the corrosion rate. Our results indicated that the corrosion rate increased with an elevation in temperature and NaCl concentration. The maximum corrosion rate was observed within the range of 3 to 4% of NaCl. Overall, this study provides valuable insights into the corrosion behavior of XC48 carbon steel in acidic and saline environments. The gravimetric analysis highlighted the influence of acid concentration on corrosion rate, including the formation of passive layers at high concentrations. The electrochemical study demonstrated the impact of temperature and NaCl concentration on corrosion rate, with higher values observed at elevated temperatures and increased NaCl concentrations. These findings contribute to a better understanding of the corrosion mechanisms and can aid in the development of effective corrosion prevention strategies for carbon steel in similar environments

The Blue Tansy Essential Oil–Petra/Osiris/Molinspiration (POM) Analyses and Prediction of Its Corrosion Inhibition Performance Based on Chemical Composition

Sustainable materials encompass a diverse range of substances used in both consumer and industrial domains. These materials are sourced in quantities that safeguard non-renewable resources and environmental equilibrium, with a focus on bio-based alternatives derived from plants. This study investigates the corrosion inhibition potential of two distinct Blue Tansy essential oils (BTES 1 and BTES 2) with varying chemical compositions. Corrosion resistance for mild steel in 1 M HCl environment was assessed using weight loss and Potentiodynamic polarization techniques. The evaluation of BTES 1 and BTES 2 revealed compelling insights. Notably, their inhibition efficiency exhibited an intriguing, damped oscillation pattern with fluctuating concentrations. Remarkably, at 0.5 g/L concentration, BTES 1 achieved an impressive 80% inhibition, while BTES 2 demonstrated a substantial 70% inhibition at 2.5 g/L. This behavior stems from intricate interactions among active compounds, leading to protective film formation and competitive adsorption effects. Importantly, congruence between weight loss measurements and potentiodynamic polarization curves fortified the reliability of outcomes. The study also confirmed BTES as a mixed-type inhibitor, as indicated by polarization curves. Furthermore, Petra/Osiris/Molinspiration (POM) analyses were conducted to unravel molecule interactions, elucidate toxicity risks, and assess bioactivity scores. This comprehensive exploration sheds light on the interplay between sustainable materials, corrosion inhibition efficacy, and complex molecular dynamics, enhancing our understanding of environmentally conscious corrosion prevention strategies.

Natural Polyphenols and the Corrosion Protection of Steel: Recent Advances and Future Perspectives for Green and Promising Strategies

Corrosion is recognized as an unavoidable phenomenon and steel, particularly carbon steel, is strongly susceptible to corrosion. Corrosion damages cause serious material, energy, and economic losses as well as negative impacts on the environment. As a result, research interest has been focused on the development of effective corrosion prevention strategies. However, some of the most commonly used corrosion inhibitors, such as chromates and pyridines, are harmful to human and environmental health. Polyphenols are natural, non-toxic, and biodegradable compounds from plant sources or agricultural by-products. Polyphenols’ chelating capacity has been acknowledged since the 1990s, and tannins, in particular, have been widely exploited as green rust converters in phosphoric acid-based formulations to recover rusty steel. Polyphenolic compounds have recently been investigated as a method of corrosion prevention. This review overviews not only the polyphenolic rust converters, but also the application of green anticorrosive coatings containing polyphenols. Moreover, polyphenols were discussed as an active component in corrosion-inhibiting primers to also promote strong adhesion between the steel surface and the topcoat layer. Finally, an overview of the use of polyphenolic additives in coatings as sustainable systems to improve corrosion resistance is provided.

Exploration and Insight of Dynamic Structure Evolution for Electrocatalysts

ConspectusElectrochemical energy technology is crucial for transitioning from fossil fuels to renewable energy sources due to its clean, efficient, and sustainable nature. Electrocatalysts are capable of maximizing energy conversion efficiency in a practical electrochemical energy technology by accelerating the charge transfer at the electrode–electrolyte interface, in which the structure and composition of the electrocatalyst directly determine the catalyst performance. Therefore, advanced electrocatalysts possess not only an optimal structure and composition but also sufficient self-stability in electrochemical processes to achieve continuous and efficient energy conversion. However, the structural evolution of electrocatalysts in various electrocatalytic processes has been gradually revealed and intensified, which hinders the practical application of electrocatalysts in electrochemical energy technology.The electrocatalytic process involves the adsorption and bonding of reactants on active sites, and this results in an instantaneous change in the structure of electrocatalysts. Structural evolution of electrocatalysts proposed here emphasizes the change in the surface or internal structure/composition of electrocatalysts in electrocatalytic reaction systems due to factors such as reaction medium, reactants, potential, and so on. Generally, structural evolution of electrocatalysts involves the transformation of active sites/phases of electrocatalysts under reaction potentials. This process, known as reconstruction, can lead to changes in activity and/or selectivity. Related research focuses on how to control and utilize reconstruction to prepare robust electrocatalysts. However, reconstructed catalysts may not always maintain structural stability and may undergo further structural evolution, such as the loss or passivation of active components, eventually leading to deactivation. This further reconstruction is commonly referred to as electrocatalyst corrosion, which emphasizes the final degradation of catalytic activity due to the structural evolution of electrocatalysts. The related research focuses on the inducement of triggering corrosion and the more critical corrosion prevention strategies. Therefore, it is urgent to clarify the inducement of corrosion and formulate corrosion prevention strategies, such as designing corrosion-resistant electrocatalysts. However, due to the harsh and complex electrochemical environment/conditions and the dynamic and changeable structure evolution behavior of electrocatalysts, it is challenging to clarify the structure evolution mechanism/law and catalytic mechanism. It is also impossible to establish an accurate structure–activity relationship and further guide the design and preparation of high-efficiency corrosion-resistant catalysts.In this Account, we present recent research progress on the structural evolution of electrocatalysts. We first discuss electrocatalyst reconstruction in electrolysis systems, including the behavior and mechanism of reconstruction and several high-efficiency reconstructed catalysts prepared by manipulating reconstruction. We also introduce unique microbially induced synthesis technology that can upgrade reconstruction synthesis. Next, we examine the corrosion of Pt-based catalysts in the oxygen reduction reaction and propose a Pt dissolution mechanism caused by adsorbed oxygenated species. We suggest corrosion-resistant Pt–Ni catalysts, and extendable carbon-coated corrosion resistance strategies are further suggested. Finally, we propose challenges and opportunities for the structural evolution of electrocatalysts in electrochemical energy technologies.

Will It Rust? A Set of Simple Demonstrations Illustrating Iron Corrosion Prevention Strategies at Sea

Corrosion of metal, especially iron, is a natural electrochemical process that costs billions of dollars every year. Educating college and precollege students, our future STEM professionals, about the chemistry that governs corrosion and its prevention strategies is of paramount importance. In this manuscript, we share a few simple iron corrosion-related activities developed into a demonstration video that helped celebrate the 2021 National Chemistry Week and was used to accompany general chemistry lectures on electrochemistry. These easy-to-setup activities with clear and dramatic effects effectively demonstrated concepts of equilibria including Le Chatelier’s principle, buffers, oxidation and reduction potentials, and factors such as metal coupling, salinity, pH, and temperature that impact rusting and its inhibition. These demonstration activities, with an emphasis on maritime applications, may also be adapted for precollege science camps or chemistry laboratories.

Study of the mechanical and corrosion resistance properties of ferrocement

Ferrocement is a lightweight, homogeneous and versatile structural material which is made as a composite of wire mesh and tightly wound skeletal steel impregnated with cement mortar. Ferrocement excels reinforced concrete system because of the minimal formwork and scaffolding requirement, possibility of casting elements on ground at site, fast erection and decrease in time of construction, and savings in the overall cost. Even though ferrocement has been used for various applications since 1800s, the technology is not properly standardized and unconventional local construction practices continue to prevail. Due to this and the poor workmanship, the durability of ferrocement structures has become an issue. Factors such as the corrosion of mesh and or the skeletal reinforcement, improper mix design etc. lead to deterioration of ferrocement structures. The major corrosion prevention methods used in reinforced concrete systems are application of coating to the steel such as epoxy or cement polymer composite (CPC) coatings and use of corrosion inhibitor in the cementitious matrix. The present study evaluates the possibility of adoption of these corrosion prevention strategies in ferrocement. The objective of the study is to analyse the flexural and corrosion resistance behaviour of four different types of ferrocement systems. The systems studied include ferrocement with normal welded mesh in normal cement mortar(WM); CPC coated weld mesh in normal cement mortar (CPC); normal weld mesh in cement mortar with corrosion inhibitor (WM CI); and CPC coated weld mesh in cement mortar with corrosion inhibitor (CPC CI). The corrosion analysis is done by using half cell potential measurements following ASTM C876-15 and flexural analysis by flexural strength test following IS 516: 1959. The results indicate that usage of both corrosion inhibitor and CPC coating can prominently increase the durability of ferrocement structures.

Compatibility of fabrication of superhydrophobic surfaces and addition of inhibitors in designing corrosion prevention strategies for electrodeposited nickel in saline solutions

The aim of this study is to assess the synergistic effect of two corrosion control strategies: application of an inhibitor and enhancing the surface superhydrophobicity, for protection of electrodeposited nickel in saline solutions. For this purpose, 4-Mercaptopyridine (C5H5NS) was added to the synthetic sea water solution and its corrosion inhibition efficiency was evaluated on electrodeposited smooth bright nickel layer and nickel films with hierarchical micro/nano structure. Stearic acid was used to tune the wetting properties of nickel films, from hydrophilic to superhydrophobic. Contact angle measurement, scanning electron microscopy, and Fourier-transform infrared spectroscopy were utilized in the characterization of deposited nickel layers. Potentiodynamic polarization and electrochemical impedance spectroscopy were employed to assess the corrosion inhibition performance of inhibitor on different nickel films. Our results indicate that simultaneous increase in the surface hydrophobicity and adsorption of corrosion inhibitor strategies does not yield a better corrosion resistance and that the most effective corrosion inhibition can be obtained on the bright smooth sample after a prolonged immersion in the corrosive solution. Furthermore, we show that the contact angle alone cannot be used to indicate the corrosion inhibition capability of an inhibitor.

Intersection of corrosion prevention strategy and practice

Purpose The purpose of this paper is to objectively evaluate the cost benefit of applying corrosion prevention coatings throughout a mid-life logistics fleet supporting the Canadian Army. Design/methodology/approach A database of maintenance records for an Army logistics vehicle throughout a four-year study period is mined. Statistical analysis (primarily ANOVA) accounting for the frequency of treatment and geographic region is executed. Findings Statistical analysis indicates counter-intuitive results. Vehicles that are most frequently treated to prevent corrosion incur the highest maintenance costs. Consultation with operational units suggests that a strategic approach to corrosion prevention is largely absent. Instead, vehicles are treated on an ad hoc basis, or – equivalently – on an as available basis. Practical implications Among high tempo organizations, vehicles most readily available to maintenance support are those that are in the greatest state of disrepair. Vehicles that are in better condition are preferred by operators for daily operations and are not available. Consequently, the vehicles that are subject to preventative maintenance most often are those near their end-of-life or are in disrepair and therefore gain little through further investments in corrosion prevention initiatives. Originality/value Clearly, having corrosion prevention compounds applied to a fleet on an ad hoc basis suffers from the natural bias occurring among operators to retain vehicles in best condition for operational purposes. Corrosion prevention requires a more strategic approach including disciplined maintenance operations in order to provide dividends on a fleet-wide basis.

Corrosion prevention prospects of polymeric nanocomposites: A review

Corrosion is a serious problem for implementing metallic components and devices in industrial zones. Considerable effort has been made to develop corrosion prevention strategies. Initially, paints, pigments, and organic coatings have been applied to prevent metal corrosion. Consequently, conjugated polymers, epoxy resin, phenolics, acrylic polymers, and many thermoplastics as well as thermoset resins have been used to inhibit corrosion. Lately, nanofillers such as fullerene, nanodiamond, graphene, graphene oxide, carbon nanotube, carbon black, nanoclay, and inorganic nanoparticle have been introduced in polymeric matrices to harness valuable corrosion protection properties of the nanocomposite. Corrosion protection performance of a nanocomposite depends on nanofiller dispersion, physical and covalent interaction between matrix/nanofiller and nanofiller adhesion to the substrate. Moreover, a high performance anti-corrosion nanocomposite must have good barrier properties, and high scratch, impact, abrasion, and chemical resistance. Thus, polymeric nanocomposites have been found to prevent corrosion in aerospace and aircraft structural parts, electronic components, bipolar plates in fuel cells, and biomedical devices and systems. However, numerous challenges need to be addressed in this field to attain superior corrosion resistant nanocomposites. Future research on polymer nanocomposites has the potential to resolve the current challenges of metal corrosion through entire replacement of metal-based materials with advanced nanomaterials.

Corrosion of reinforcing steel in concrete sewers

Hydrogen sulfide is a controlling factor for concrete corrosion in sewers, although its impact on sewer rebar corrosion has not been investigated to date. This study determined the corrosion mechanism of rebar in sewers by elucidating the roles of chloride ions, apart from the effects of hydrogen sulfide and biogenic sulfuric acid. The nature and distribution of rusts at the steel/concrete interface were delineated using the advanced mineral analytical techniques, including mineral liberation analysis and micro X-ray diffraction which is the first-ever use in such studies. The corrosion products were found to be mainly iron oxides or oxy-hydroxides. H2S and biogenic sulfuric acid did not directly participate in the product formation of steel partly covered by concrete or directly exposed to sewer atmosphere. Instead, chloride ions played an important role in initiating steel corrosion in sewers, supported by a thin chloride-enriched layer at the steel/rust interface. Away from the chloride-enriched layer, iron oxides accumulated on both sides of the mill-scale to form a corrosion layer and corrosion-filled paste respectively. The corrosion layer around rebar circumference was non-uniform and the rust thickness with respect to polar coordinates followed a Gaussian model. These findings support predictions of sewer service lifetime and developments of corrosion prevention strategies.

Microstructural Modeling of Pitting Corrosion in Steels Using an Arbitrary Lagrangian–Eulerian Method

Two microscale numerical models are developed in this work using a moving-mesh approach to investigate the growth process of pitting in different iron phases and the corrosion prevention capability of polyaniline (PANi) on steels. The distributions of corrosion potential and current in the electrolyte-coating-steel system are computed to evaluate the anti-corrosion ability of PANi. The arbitrary Lagrangian–Eulerian approach was used to accomplish the continuous remesh process as was needed to simulate the dynamic growing forefront of the modeled pitting domain. Experimental validation of the numerical models was conducted using the technique of scanning kelvin probe force microscopy (SKPFM). The SKPFM-scanned surface topography and Volta potential difference exhibit comparable results to and thereby prove the numerical results. The potential distribution in the electrolyte phase of the validated models shows that the corrosion pit grows faster in the epoxy-only-coated steel than that in the PANi-primer-coated steel over the simulation time; also, the corrosion pit grows faster in the ferrite phase than in the cementite phase. The simulation results indicate that the epoxy-only coating lost its anti-corrosion capability as the coating was penetrated by electrolyte, while the PANi-based coating can still protect the steel from corrosion after the electrolyte penetration. The models developed in this work can be used to study the mechanisms of pitting corrosion as well as develop more effective corrosion prevention strategies for general metallic materials.

Corrosivity Measurements of Singapore and the Effect of Tropical Atmosphere on Corrosion of Different Metals

Atmospheric corrosion is clearly the most noticeable of all corrosion processes. Tremendous amount of economic losses are caused by atmospheric corrosion. Thus it is imperative to know the level of atmosphere’s aggressiveness or in other words “corrosivity”, before anyone designs or plans any corrosion prevention strategy. Corrosivity values were not recorded before in Singapore though those were measured and recorded in other countries.In the aim of filling this gap, test sites had been established on three locations of Singapore. Thus corrosivity readings were measured and recorded according to ISO 9223:2012 for the first time in Singapore. Both determined and estimated corrosivity values were recorded upon completion of one year exposure of standard metal samples and atmospheric constituents / pollutant measurements respectively. Final objective of this work is to correlate some accelerated cyclic corrosion test parameters with these Singapore atmospheric corrosivity values. Results will be useful for both industrial and research needs in future. A detail discussion together with results will be presented.

Prevention and cost of atmospheric corrosion in Mauritius

PurposeThe purpose of this paper is to obtain a better insight into the impact of atmospheric corrosion in Mauritius by investigating the corrosion prevention strategies used in the country and determining the related costs.Design/methodology/approachCompanies and organizations, in various industrial sectors, affected by atmospheric corrosion were selected. They were inspected and surveys were performed in order to fulfill the aim of the study.FindingsIt has been observed that extensive atmospheric corrosion problems have been encountered in the capital city, leading to the use of a range of corrosion prevention methods. However, carbon steel, which corrodes easily, is very commonly used in the country. This leads to the wide use of alkyd‐based barrier coatings. The cost of atmospheric corrosion has been found to be equal to 0.38 per cent of the GDP.Social implicationsThis study is expected to raise concern on the problem of atmospheric corrosion in Mauritius and the related waste in materials.Originality/valueThis study is expected to help in adopting corrosion prevention policies and strategies in Mauritius.