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With the ongoing advancements and innovations of electronic device, the demand for low-melting-point solder is rising, especially for flexible printed electronics. The service environments of electronic device are complex and diverse, which have raised concerns regarding long-term service reliability in solder materials. In this work, a novel type of 30In33Sn25Bi4AgxZn low-melting-point alloy solder was proposed. The effects of Zn content on the corrosion resistance and electrochemical migration (ECM) resistance of the alloy system were investigated through electrochemical test and water drop test (WDT). The passivation film on the surface and the amorphous region of InSnBiAg8Zn alloys effectively inhibits the anodic dissolution of Zn atoms, improves the corrosion resistance of the alloy and delays the occurrence of electrochemical migration failure. The microscopic mechanism of ECM was revealed by conducting in-situ observations of the migration process of the alloy solder and analyzing the composition and morphology of the anode alloy and the migration products.

Due to the presence of corrosive contaminants in the air, metals naturally corrode when exposed to the environment. Air pollution, in conjunction with climate conditions, may significantly deteriorate outdoor materials, especially metals and hence, the need for corrosion control. Using inhibitors is a powerful strategy that is frequently employed for corrosion prevention and control. Chemical inhibitors are often used. However, due to their low effectiveness and stringent environmental regulations, the majority of chemical corrosion inhibition techniques are becoming less desirable. For this reason, there is an increasing interest in and focus on biological inhibition approaches, which most recently have included the use of microbes. Microbiologically-influenced corrosion inhibition (MICI) is apparently far more complex than traditional corrosion inhibition procedures. A current overview of the mechanisms that have been used or may be efficient for MICI technologies is important in order to facilitate the advancement of MICI and its practical industrial applications, especially for atmospheric corrosion caused by air pollutants, for which there is little information in the reviewed literature. Therefore, this review addresses the role of microbes, like Pseudomonas putida, in the inhibition of atmospheric corrosion of metals and brings the reader up-to-date on the few literatures existing on the subject. The review describes and characterizes MICI for atmospheric corrosion as a developing field still in need of enthusiastic researchers to further investigate the area in order to establish useful methodologies, procedures, and technologies for later adoption in industrial terrains and applications. [ABSTRACT FROM AUTHOR]

The phenomenon of corrosion threatens metallic components, human safety, and the economy. Despite being eco-friendly and promising as a corrosion inhibitor, acridine has not been explored to its full potential. In this review, we have discussed multiple biological activities that acridines have been found to show in a bid to prove that they are environmentally benign and much less toxic than many inhibitors. Some synthetic routes to acridines and substituted acridines have also been discussed. Thereafter, a multitude of acridines and substituted acridines as corrosion inhibitors of different metals and alloys in various corrosive media have been highlighted. A short mechanistic insight into how acridine-based compounds function as corrosion inhibitors have also been included. We believe this review will generate an impression that there is still much to learn about previously reported acridines. In the wake of recent surges to find efficient and non-toxic corrosion inhibitors, acridines and their analogs could be an appropriate answer. [ABSTRACT FROM AUTHOR]

Biosurfactants are capable of meeting the challenges of the oil industry by reducing its social, economic, and environmental impacts. The aim of the present study was to produce a biosurfactant from Pseudomonas cepacia CCT6659 in 2.0-L and 5.0-L bioreactors and evaluate its long-term stability over 120 days of storage. Ecotoxicological tests were performed with Artemia salina larvae during the use of the biosurfactant to increase in solubilisation of heavy oil in seawater compared to the use of a chemical surfactant. The biosurfactant was also applied as a bioremediation agent for sand contaminated with a petroleum product and as an inhibitor of corrosion on metallic surfaces. A concentration of 35.0 g/L of the biosurfactant was achieved in the 5.0-L reactor and low toxicity to the bioindicator was found, with an approximate 40% reduction in the mortality rate compared to the chemical surfactant. The stability of the biosurfactant was demonstrated by the maintenance of its tensioactive properties throughout the entire storage period. Besides its advantageous bioremediating capacity, with the removal of 94.5% of oil from sand, the biosurfactant proved to be an effective inhibitor of both metallic corrosion and microbial biofilm, with minimal loss of mass (15.7%) compared to the control condition, demonstrating its potential for industrial applications. • The strain of Pseudomonas cepacia CCT6659 produced 35.0 g/L in a 5.0-L reactor. • The biosurfactant showed low toxicity compared to chemical surfactant. • The biosurfactant showed stability under extreme environmental conditions. • The biosurfactant removed 94.5% of the hydrocarbon adsorbed in sand. • The biosurfactant was able to reduce both metallic corrosion and microbial biofilm. [ABSTRACT FROM AUTHOR]

Camphor wood is welcomed by museums due to its insect-repelling effect but the smell indicates a potential risk to the collections. In order to judge the suitability of camphor wood as a museum storage material, typical camphor wood (Cinnamomum camphora) samples aged for different years were evaluated by conducting the Oddy test. Gas chromatography–mass spectrometry (GC-MS), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), and time of flight–secondary ion mass spectrometry (ToF-SIMS) were applied to identifying the volatile organic compounds (VOCs) emitted by the materials and the corrosion products, respectively. The results showed that the camphor wood samples led to visible corrosion on copper and lead coupons. GC-MS indicated that the major VOCs emitted were terpenes and their derivatives, while XRD, EDS, and ToF-SIMS provided various clues to the corrosion mechanisms. Pb10(CO3)6(OH)6O and CuO were regarded as the major corrosion products of lead and copper coupons, respectively. The study provides the museum curators and the conservators with abundant information to reassess the application of camphor wood to museums as well as a different way to understand the mechanism of metallic corrosion caused by camphor wood. [ABSTRACT FROM AUTHOR]

Abstract In the UK, the typical route being followed to handle metallic Intermediate Level Waste (ILW) derived from decladding of irradiated nuclear fuel is to primarily deposit it within stainless steel drums/boxes and subsequently encapsulate it into grout. Thus, a monolithic bond between the waste and the encapsulants can be achieved. However, recent inspections have revealed bulges around the circumference in a considerable proportion of the inspected packages. This distortion has been ascribed to the interior metallic corrosion–induced volume expansion, occurring throughout the waste packages storage period. Throughout this period, the volume expansion taking place in the core of the ILW drums has imposed continuously growing levels of strain on the surrounding encapsulants, i.e. grout and steel confinement. As a result, the encapsulants may exhibit considerable damage, in the form of cracks in the grout or/and steel distortion, threatening the integrity of the packages and, consequently, raising safety concerns within the nuclear community. Herein, experimental work performed on ILW drum–simulant packages is described, attempting to evaluate the performance of the packages under an internal corrosion–induced volume expansion. Graphical abstract Image 1 Highlights • Accelerated corrosion experiments on uranium encapsulated in grout. • Grout degradation due to interior corrosion–induced volume expansion. • Cracks in the grout initiate and propagate during early corrosion stages. • Migration of the corrosion products does not occur at early corrosion stages. [ABSTRACT FROM AUTHOR]

Recently, more and more attention is paid on applications of molten chlorides in concentrated solar power (CSP) plants as high-temperature thermal energy storage (TES) and heat transfer fluid (HTF) materials due to their high thermal stability limits and low prices, compared to the commercial TES/HTF materials in CSP-nitrate salt mixtures. A higher TES/HTF operating temperature leads to higher efficiency of thermal to electrical energy conversion of the power block in CSP, however causes additional challenges, particularly increased corrosiveness of metallic alloys used as containers and structural materials. Thus, it is essential to study corrosion behaviors and mechanisms of metallic alloys in molten chlorides at operating temperatures (500-800 °C) for realizing the commercial application of molten chlorides in CSP. The results of studies on hot corrosion of metallic alloys in molten chlorides are reviewed to understand their corrosion behaviors and mechanisms under various conditions (e.g., temperature, atmosphere). Emphasis has also been given on salt purification to reduce corrosive impurities in molten chlorides and development of electrochemical techniques to in-situ monitor corrosive impurities in molten chlorides, in order to efficiently control corrosion rates of metallic alloys in molten chlorides to meet the requirements of industrial applications. [ABSTRACT FROM AUTHOR]

Inhibition mechanisms of many corrosion inhibitors in deaerated acid and oxygenated neutral solutions have been discussed based on the hard and soft acids and bases principle (HSAB principle). However, inhibition effects of precipitation inhibitors, such as propargyl alcohol CH=CCH2OH; bismuth(III) ion, Bi3+; and benzylthiocyanate, C6H5CH2SCN, which are effective for corrosion of metals in the acid solutions, have not been described. This paper discusses the inhibition mechanisms of these precipitation inhibitors in aqueous acid solutions based on the HSAB principle. [ABSTRACT FROM AUTHOR]

Protecting Cultural Heritage (CH) from corrosion and other environmental damages, mainly involving metallic or organic layers contained in artwork, represents a major challenge for conservation scientists. Electrochemical techniques provide useful information about the deterioration effects of metallic coatings and organic layers. Recently, Electrochemical Impedance Spectroscopy (EIS) has been successfully applied in the study of metallic corrosion. However, EIS has not succeeded in becoming a routine technique, due to problems regarding both instrumental apparatus (which is not ideal for in situ analysis, especially with previous cell configurations), and the difficulty with data processing. At the same time, new portable electrochemical sensors, immunosensors, and biosensors have successfully made a scientific impact, mainly with in situ diagnosis of organic components contained in CH objects. For this purpose, this review presents two sections: the first describes the analytical optimization of impedance electrochemical cell geometries that are suitable for in situ metal-coating investigation; the second reports on the assembly of small electrochemical sensors, immunosensors, and biosensors, which useful for in situ organic layer characterization. This overview summarizes the state of the art regarding the application of electrochemical techniques and small electrochemical devices as alternative tools for the understanding of CH.

• Three classes of microalgae exhibited corrosion inhibition effects on carbon steel. • Inhibition efficiencies from weight loss and electrochemical tests ranged 44.7–83.8%. • Passivated films included biological and corrosion product films of iron compounds. • The anticorrosive property of the passivation films slightly decomposed with time. • These marine microalgae had potential as green corrosion inhibitors in f/2 medium. The effect of marine microalgae on the corrosion behavior of carbon steel (CS) still needs further investigation due to their dual roles. In this study, the corrosion behavior of Q235 CS specimens in f/2 medium with absence and presence of three classes of marine microalgae Synechococcus sp., Chlorella sp., and Thalassiosira sp. was investigated during a 16-day immersion period by the weight loss, electrochemical impedance spectroscopy, potentiodynamic polarization curve, and surface analysis techniques. The biomass of the three microalgae was monitored at the same time. The results showed that the values of weight loss and corrosion current density decreased, and the values of charge transfer resistance increased in the CS specimens treated with these microalgae. On day 16, the inhibition efficiency of Thalassiosira sp. group was the highest (80.78%), followed by Chlorella sp. group (70.80%), and finally Synechococcus sp. group (69.38%). But the inhibition efficiency diminished with time. Furthermore, in these microalgal treatment groups, the passivation films were found to consist of a biofilm and a corrosion product film. This study revealed that the three microalgae can effectively strengthen the barrier of the CS specimens in the f/2 medium, leading to slow down their corrosion rates. [ABSTRACT FROM AUTHOR]

Early detection of metallic corrosion is one considerable method to reduce imperceptible disasters nowadays. Fluorescent coatings with high sensitivity and long lifetimes for use in the early detection of metallic corrosion are in high demand, but they are presently difficult to prepare. Inspired by the chameleon's skin, which is capable of switching its color in different atmospheres sensitively and reversibly, we proposed herein a facile and universal all-in-one strategy of combining the fluorescent sensitivity and dynamic hydrogen bonds in a hydrogel to develop a reusable corrosion detection tape to cover metal surfaces. The fluorescent hydrogel tape was constructed using free radical copolymerization of monomers [hydroxyethyl methylacrylate (HEMA) and tetraphenylethene derivatives (TPEPy)]. Due to the aggregation-induced emission (AIE) behavior of TPEPy, the poly(HEMA- co -TPEPy) hydrogel is capable of monitoring the traces of corrosion via the release of ferric ions with a concentration as low as 10 -5 M. Moreover, due to the dynamic hydrogen bonds of hydroxyethyl groups in hydrogel networks, the fluorescent hydrogel tape exhibited good adhesion and well reusability for over 10 applications to effectively warn against early corrosion of stainless steel. This non-destructive and reversible method of early corrosion detection can provide valuable signals when maintenance is needed before the metal suffers serious damage.

Abstract: In this research, different metallic materials commonly used in the manufacture of autoparts were immersed in a 20% bioethanol–80% gasoline (E20) blends and their performance was evaluated. In order to determine the corrosive behavior and corrosion inhibition of these metals in the E20 blend, a continuous immersion test, a mass loss determination test, electrochemical impedance spectroscopy (EIS) and surface characterization were performed. EIS was carried out under both static and hydrodynamic conditions. Metallic materials evaluated were: aluminum–silicon alloy, chromium steel, carbon steel, stainless steel, aluminum, copper and tin. The immersion test indicated that carbon steel had the greatest susceptibility to corrosion in E20. According to the polarization resistance values (Rp) estimated by EIS, carbon steel and copper exposed to E20 exhibited a relatively high susceptibility to corrosion, while the other metals showed high Rp values indicating a low susceptibility to corrosion. The addition of 0.1gl−1 of ethanolamine in the E20 mixture as a corrosion inhibitor for carbon steel was effective during the first 30days of immersion. [Copyright &y& Elsevier]

Abstract: The development of effective anticorrosion pre-treatments for metallic substrates is an issue of great importance for durability of metal structures and components. In this work, we proposed and demonstrated the concept of self-repairing coating for corrosion protection of aluminum alloys, using cagelike oil core/silica gel shell particles. These micron-scale, cagelike smart microspheres with opened and closed pores were successfully fabricated, and at the same time encapsulated repairing agent (methyl methacrylate) and catalysts (potassium persulfate and sodium thiosulfate) into the microspheres, respectively. Such smart particle composites (SPCs) were prepared based on an interfacial self-assembly process and sol–gel reaction. They were then self-assembled on the AA2024 aluminum alloy surface, followed by the application of a sol–gel film. The hybrid film worked as a primer coating featuring the self-repairing property. Both the EIS and SEM/EDS data demonstrated that the encapsulated repairing agent was released as a response to external stimulus (scratches) and polymerized to repair the coating defects. By comparing the corrosion rate of AA2024 in three coating systems, the self-repairing effect is quantified to be 22% after 2h immersion in deoxidized 3% NaCl solution. [Copyright &y& Elsevier]

Abstract: In this research, a specific surface modification technology was developed for stainless steel bipolar plates to obtain a corrosion-resistant oxide film. The surface roughness was measured, and an electron spectroscopy analysis (ESCA) was conducted to verify the chemical composition of the surface layer. From the binding energy of the ESCA spectrum, the amounts of chemical shift were used to identify the major chemical compositions. The thickness of the oxide film was analyzed by auger electron spectroscopy (AES). From the results of the ESCA and AES analyses, the effects of the surface modification on the integrity of the surface were evaluated. Uniform corrosion and localized corrosion tests were also conducted to investigate any improvement on the corrosion characteristics. A single cell was assembled for cell performance tests. The surface of the treated plates was bright and smooth. The ESCA and AES analyses showed that the treated plates had a much higher chrome content. The metallurgical structure was dense with substantially less defects. The chemical and electrochemical properties were more stable. The corrosion rates of the treated plates were also much improved, resulting in better electric conductivity, stable cell performance as well as longer cell life. [Copyright &y& Elsevier]

• A novel and optimized two-stage AC/DC/AC procedure is proposed. • Two water-based primers are aged by NSS test and by the new AC/DC/AC procedure. • The degradation promoted by the NSS test was periodically characterized by EIS. • EIS results show that the aging promoted by AC/DC/AC closely mimics the NSS test. • The new procedure reduced the overall aging time to 25% of that obtained in NSS test. Organic coatings are nowadays the most common and cost-effective approach to extend the service life of metallic structures subjected to weathering conditions. The development of new and more effective protective coatings is closely related to the rapid assessment of the anticorrosive performance before industrialization. Currently, the coating/metallic substrate system evaluation is made using accelerated standardized test methods. However, the time needed to perform such tests can be long, and in some cases can hold up for thousands of hours. The AC/DC/AC method is an accelerated cyclic test, consisting of a combination of electrochemical impedance spectroscopy (EIS/AC) characterization and cathodic polarisations (DC). The latter technique has been widely used to assess the adhesion of coatings to the metallic substrate but, to the best knowledge of the authors, no clear evidences have been provided that the aging promoted by AC/DC/AC is comparable to the one promoted by standardized accelerated aging tests, such as the neutral salt spray test. Said comparison is necessary to be able to support the use of the AC/DC/AC method to assess the anticorrosive performance of coatings. This work addresses this gap and goes further, proposing an innovative two-stage AC/DC/AC procedure that allows a better control of the physical delamination inherent to this technique, while promoting a chemical and electrochemical attack of coating and metallic substrate. Two water-based organic primers applied on cold rolled steel were aged by neutral salt spray (aging characterized by EIS) and by the proposed AC/DC/AC procedure. The obtained results were critically compared based on the EIS analysis. It was observed that the two-stage AC/DC/AC procedure mimicked the degradation mechanisms occurring during the neutral salt spray test, but producing results in less than 25% of the aging time. [ABSTRACT FROM AUTHOR]

Protecting Cultural Heritage (CH) from corrosion and other environmental damages, mainly involving metallic or organic layers contained in artwork, represents a major challenge for conservation scientists. Electrochemical techniques provide useful information about the deterioration effects of metallic coatings and organic layers. Recently, Electrochemical Impedance Spectroscopy (EIS) has been successfully applied in the study of metallic corrosion. However, EIS has not succeeded in becoming a routine technique, due to problems regarding both instrumental apparatus (which is not ideal for in situ analysis, especially with previous cell configurations), and the difficulty with data processing. At the same time, new portable electrochemical sensors, immunosensors, and biosensors have successfully made a scientific impact, mainly with in situ diagnosis of organic components contained in CH objects. For this purpose, this review presents two sections: the first describes the analytical optimization of impedance electrochemical cell geometries that are suitable for in situ metal-coating investigation; the second reports on the assembly of small electrochemical sensors, immunosensors, and biosensors, which useful for in situ organic layer characterization. This overview summarizes the state of the art regarding the application of electrochemical techniques and small electrochemical devices as alternative tools for the understanding of CH. [ABSTRACT FROM AUTHOR]