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The Martinique island, located in the Caribbean Sea, is subject to the stranding of Sargassum algae, which decompose and release toxic gases, such as hydrogen sulfide or ammonia. This study aims to investigate the atmospheric corrosion of zinc in these conditions. For this purpose, three sites in Martinique more or less impacted by Sargassum algae stranding were selected. Mass loss results after 1‐year exposure range from 1.9 µm for the site least impacted to 45.3 µm for the site most affected by Sargassum algae. This high value proves that the presence of Sargassum algae caused significant zinc degradation. The morphological structures and properties of the corrosion products obtained at the impacted and non‐impacted sites differ significantly. In the absence of Sargassum algae, "classical" corrosion products based on hydrozincite, simonkoleite, gordaite, and zinc hydroxylsulfate are observed. In the area close to the Sargassum seaweed stranding, the presence of elemental sulfur products, zinc hydroxylsulfate, and sphalerite is reported. [ABSTRACT FROM AUTHOR]

To improve estimation of sea salt deposition distributions on structural surfaces such as that of an airborne sea salt and corrosion sensor, we numerically simulated approaching flows with particles around a vertical flat plate. This is a typical object that mimics a sensor with a support plate. We used a computational fluid dynamics (CFD) model based on the unsteady Reynolds averaged Navier-Stokes equation. After validating the results by comparison with existing studies for flows with particles around a cylinder, we examined the changes in particle impaction efficiency on the plate with different approaching flow directions (0, 45 deg) and particle diameters (5 © 10-6-1.6 © 10-4 m). The impaction efficiency increases rapidly with particle diameter, whereas the influence of flow direction is small. Such increases in impaction efficiency are due to contributions from inertial impaction, and thus the variation in Stokes number with wind speed and the plate size can be used to predict the flow and particle conditions required for increases in impaction efficiency. The efficiencies for small particles on the front surface of the plate are higher than those on a cylinder. The impactions of small particles on the plate are locally activated by flow separations around a bluff body, whereas those on a cylinder are caused by intercepts without flow separations. [ABSTRACT FROM AUTHOR]

A series of morpholine salt volatile corrosion inhibitors (VCIs) were synthesized via solid-phase chemical reactions. The corrosion inhibition performance was assessed using evaporation weight loss, VCI capability, and corrosion weight loss tests. The corrosion inhibition mechanisms of the morpholine salt VCIs for carbon steel in atmospheric conditions were explored through electrochemical testing under thin film electrolytes, X-ray photoelectron spectroscopy (XPS), and computational simulations. Morpholine carbonate exhibited higher volatility. Corrosion weight loss tests showed an >85% reduction for steel treated with morpholine benzoate or morpholine carbonate. The inhibitors' inhibition mechanism, elucidated through X-ray photoelectron spectroscopy (XPS) and computational simulations, revealed that morpholine carbonate and benzoate form protective layers via physical and chemical adsorption on the steel surface, coordinating with iron atoms through nitrogen and oxygen atoms. Quantum chemical calculations demonstrated that morpholine carbonate had stronger adsorption energy and electron transfer capabilities, indicating superior corrosion inhibition performance over morpholine benzoate. [ABSTRACT FROM AUTHOR]

This research explores the corrosion behavior of beryllium bronze over a period of 29 years in an industrial atmosphere, revealing an average corrosion rate of 0.557 μm·a−1. The skyward patina layer primarily consists of Cu2O, Cu4SO4(OH)6 and CuSO4, while the field-ward patina layer contains Cu2O, CuO, Cu4SO4(OH)6 and CuSO4. Density functional theory (DFT) calculations and XPS analysis show that Be oxidizes preferentially, providing early-stage corrosion protection. DFT and open circuit potential measurements suggest that the patina layer on the field-ward surface is more thermodynamically stable, but cracks serve as pathways for mass transport, accelerating corrosion.

• An atmospheric corrosion model of clearance joint is developed based on COMSOL simulation software. • A dynamic modeling and analysis method for ALGRM considering atmospheric corrosion is explored. • The effects of corrosion time and different bearing materials on ALGRM are investigated. • The dynamic behavior and nonlinear characteristics of ALGRM are discussed. Atmospheric corrosion poses a significant challenge for the components of aircraft exposed to prolonged harsh weather conditions, critically impacting the safety property of aircraft landing gear retraction mechanism (ALGRM). This paper focuses on the ALGRM of a specific aircraft type, presenting a new modeling and analysis approach to assess the influence of atmospheric corrosion on dynamic behavior and nonlinear characteristics of mechanism. Initially, the dynamic model of ALGRM incorporating clearance joints is established using Lagrangian method. Numerical solutions are then obtained using the Runge-Kutta method. Subsequently, COMSOL simulation software is employed to simulate the corrosion morphology of the bearing under atmospheric corrosion, integrating the corroded bearing surfaces into the dynamic model of the mechanism. Finally, the study investigates the effects of corrosion time and different bearing materials on the dynamic behavior and nonlinear characteristics of ALGRM considering atmospheric corrosion. The results indicate that as corrosion time increases, the degradation of the dynamic behavior of ALGRM becomes more pronounced, and there are significant variations for corrosion morphology of bearing made of different materials under atmospheric corrosion. The findings of this study contribute to a broader understanding of the complex interactions between the dynamic behavior of aircraft and environmental degradation, providing some insights for designing ALGRM that are more durable and adaptable to atmospheric corrosion environments. [ABSTRACT FROM AUTHOR]

In order to evaluate the corrosion state of power grid galvanized steel components in the atmospheric environment of Anhui Province, galvanized steel samples, which were naturally exposed for 1 and 3 a, respectively, were analyzed using scanning electron microscopy(SEM), energy-dispersive X-ray spectroscopy(EDX) and X-ray diffractometer(XRD) to investigate the compositions and morphologies of the corrosion products, thereby revealing their atmospheric corrosion mechanisms. Meanwhile, the corrosion rates of the galvanized steel samples were determined using the weight-loss method, combined with grey correlation analysis, to ascertain the influence law of major environmental factors on the atmospheric corrosion rate of the galvanized steel samples. Results showed that the atmospheric corrosion products of the galvanized steel samples consisted of ZnO and minor amounts of Zn5(OH)6(CO3)2 and Zn4(OH)6SO4. The surface of the corrosion layer featured cellular protrusions composed of flaky Zn5(OH)6(CO3)2 and Zn4(OH)6SO4, forming chrysanthemum-like patterns. The structure of the corrosion layer was dense and closely bonded to the galvanized layer, providing effective protection, and thus, the corrosion degree of the galvanized steel was low. The major environmental factors affecting the atmospheric corrosion rate of the galvanized steel samples in Anhui Province were ranked as follows: temperature > relative humidity > O3 > NO2 > PM2.5 > PM10 > SO2. Temperature and atmospheric relative humidity had a more significant impact, whereas the influence of SO2 was minimal.

Hot‐dip Zn55Al‐coated steel samples have been exposed for up to 6 years at 11 different weathering sites, including marine, marine‐industrial, acid‐rain and dry atmospheres. From the mass loss measurements, Zn55Al metallic coating showed globally long‐term good corrosion resistance in all weathering conditions compared with hot‐dip Zn‐0.2Al‐coated steel (Z). Yet, weaker performance was observed on Zn55Al in high SO2 polluted atmosphere, particularly when combined with seawater aerosols. This is explained by a more acidic surface condition linked to high SO2. Although the extent of corrosion in this phase was different at the different sites, the final corrosion products formed after 6 years were rather similar at all sites. This consists of hydrous aluminium sulphate or hydrous aluminium hydroxy sulphate and, probably also a smaller amount of sulphate‐containing zinc corrosion products or Al/Zn products. [ABSTRACT FROM AUTHOR]

This article aims to investigate the atmospheric corrosion of carbon steel in a marine environment abundant in hydrogen sulfide (H2S) resulting from the decomposition of Sargassum seaweed. To accomplish this, four sites with varying degrees of impact were chosen along the coast of Martinique. The corrosion rates of steel were evaluated through mass loss measurements. After one year of exposure, the corrosion rates were notably high, particularly in atmospheres rich in Cl− ions and H2S, ranging from 107 µm to 983 µm. Complementing these findings, surface and product morphologies were characterized using scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). These analyses revealed a significant degradation of the corrosion surface in the most affected atmospheres compared to those unaffected by Sargassum seaweed strandings. Lepidocrocite (γFeOOH) was identified as the predominant product regardless of the exposure atmosphere. However, goethite (αFeOOH) was found to be present in atmospheres most impacted by H2S. [ABSTRACT FROM AUTHOR]

Urgent action is required to mitigate the severe corrosion of carbon steel in low-latitude regions. The combination of high humidity, temperature, and salinity in these areas significantly accelerates steel corrosion, posing a substantial threat to the service safety of offshore engineering equipment. This study aims to elucidate the atmospheric corrosion mechanisms of 45# steel in low-latitude coastal areas. Samples of 45# steel were exposed to atmospheric conditions over various durations in the following three geographically distinct regions: Guangzhou, Wanning, and the South China Sea. The corrosion rates were calculated using weight loss tracking and potentiodynamic polarization measurements, while surface corrosion products were examined using X-ray diffraction (XRD) tests. The findings indicate a clear correlation between the corrosion rate of 45# steel and the latitude and specific location of the test area, with the highest to lowest rates observed in the South China Sea, Wanning, and Guangzhou, respectively. Similarly, the extent of corrosion rust penetration in defective coatings followed the same order. Moreover, the protection ability index (PAI) calculations revealed that none of the tested samples formed a protective corrosion film. [ABSTRACT FROM AUTHOR]

This study discusses the comparative weatherability of three microstructures of ferrite, ferrite + bainite, and bainite, obtained by controlling the rolling and cooling processes of a well-established weathering steel by adding 3 wt% Ni in tropical marine atmospheric environments. In field exposure in the Trat (Thailand) and accelerated laboratory testing, the bainitic steel showed superior weathering resistance compared to the other microstructures. The corrosion rates after 12-month of exposure were 0.012 mm/y for ferritic steel, 0.010 mm/y for ferritic + bainite steel, and 0.009 mm/y for bainitic steel. An analysis of the electrochemical properties of the rust layer, its phase composition, and morphological observations revealed that the influence of microstructure on the atmospheric corrosion rate of weathering steels primarily depend on the density of the rust and the adhesion between the rust layer and the substrate. [ABSTRACT FROM AUTHOR]

In this work, corrosion behavior and the concurrent acoustic emission (AE) signals of AZ31 alloy under NaCl and Na2SO4 solution droplets were comparatively investigated in combination with in-situ optical microscopy observations. It was observed that after a short initial corrosion accompanied by the growth and rupture of H2 bubbles, the later corrosion behavior of AZ31 alloy mainly developed into filiform corrosion under NaCl solution droplet and pitting corrosion under Na2SO4 solution droplet. AE signals were detected in both cases. In particular, AE parameters of amplitude and duration were found to well identify filiform and pitting corrosion. AE signals were mainly correlated with the observed evolution of H2 bubbles of different shapes and positions, i.e., regularly round bubbles grew and ruptured at the filament head near the metal surface during filiform corrosion; whereas irregularly-shaped bubbles grew and ruptured at the pit mouth during pitting corrosion. [ABSTRACT FROM AUTHOR]

The cathodic protection provided by epoxy coating/epoxy zinc-rich coatings on defective areas under atmospheric and immersion conditions was studied via a Q235 wire beam electrode (WBE), scanning electron microscopy, X-ray diffraction, and surface morphology analysis. The results showed that the cathodic protection processes under the two test conditions displayed significant differences. The effective protection time of the defective area under the atmospheric condition was 1.7 times that under the immersion condition. Compared with the immersion condition, zinc particles in zinc-rich coatings under the atmospheric condition exhibited higher cathodic protection efficiency. The possible activation mechanism of zinc particles under the two conditions was elucidated. [ABSTRACT FROM AUTHOR]

In this work, nanostructured diamond particles are considered as fillers for epoxy coatings. Nanodiamonds and a diamond charge obtained as a result of detonation synthesis from a mixture of TNT and hexogen are characterized by IR spectroscopy, scanning electron microscopy, and thermal analysis. It has been shown that nanodiamonds are characterized by thermal stability up to 450°C and increase the thermal stability of epoxy coatings. The influence of nanodiamonds and diamond charge, depending on their quantity and synthesis conditions, on the physical and mechanical properties (hardness, contact angle, adhesion, impact and bending strength) of epoxy coatings is studied. The results of a study of the anticorrosion resistance of epoxy coatings with 10 wt % nanodiamonds compared to polymethylphenylsiloxane resin coating using methods of potentiodynamic polarization, linear polarization resistance, and impedance measurements, supplemented by field tests in humid tropical climates are presented. [ABSTRACT FROM AUTHOR]

Atmospheric corrosion is one of the natural phenomena with the greatest impact on the integrity of metallic infrastructures worldwide and especially in tropical environments. However, most atmospheric corrosion studies carried out in natural environments do not exceed 5 years of exposure, and studies with results of 10 or more years are even fewer. This study evaluates the corrosion kinetics of carbon and galvanized steels exposed in the downtown area of Medellín, classified as a moderate aggressiveness environment, from results obtained at 1, 2, 5, 8 and 11 years. For both materials, a corrosion kinetic equation was obtained from Log-Log plots of mass loss, useful for making long-term predictions of the deterioration of structures exposed to the atmosphere. The corrosion of the galvanized was approximately between 10 to 17 times lower than that of carbon steel. [ABSTRACT FROM AUTHOR]

High-strength steels, such as high-strength bolts or steel plates are considerably sensitive to hydrogen embrittlement. Serious safety problems in steel structures are possible, because they are exposed to atmospheric condition containing chloride ions. Embrittlement is induced by hydrogen penetration during atmospheric corrosion. We developed Double-Head Scanning Kelvin Probe (DHSKP) equipment to clarify the relationship between the corrosion process and hydrogen permeation. Each probe can simultaneously measure the corrosion potential on the corroded side and surface potential on the hydrogen-detecting side at the same time. In this study, we investigated the correlation between the corrosion potential and hydrogen permeation under changing conditions from wet to dry processes on the surface of a steel sample. During the drying process, the corrosion potential at the rust layer that precipitated in the early wetting condition showed a less noble potential locally, whereas the surface potential of the Pd film on the hydrogen detection side showed a less noble potential locally. The hydrogen permeation sites were limited to small spots in the opposite area, where the corrosion potential showed a less noble local-potential during the drying process. Hydrogen penetration by corrosion likely occurs in acidic liquids under the rust layer during the drying process.

The study reports the development of a liquid smoke solution of rice husk ash (RHA) as a green corrosion inhibitor in NH4Cl solution in approaching corrosion protection for refinery facilities. The recent utilization of RHA has a partial solution to address the possible chemical to form a filming layer to disconnect bare metal and their environment. This work prepared the RHA solution by condensing the RHA vapor before adding it to various concentrations. The corrosion test of potentiodynamic and electrochemicals intends to discover the inhibitor's corrosion resistance before examining the electronic transition corresponding to the contribution of several functional groups using Ultraviolet Visible (UV–Vis) and Fourier-Transform Infrared Spectroscopy (FTIR). Surface evaluation intends to unveil the nature of the corrosion by utilizing the Scanning Electronic and Atomic Force Microscope. The corrosion test result shows the depression of corrosion rate to 0.120 mmpy with high efficiency beyond 96 % in the addition of 7.5 ppm RHA inhibitor. The greater Nyquist semicircle diameter at high concentrations increases the adsorption of the RHA on the surface of C1018. The electronic transition of n–π* and π –π* shows an extensive contribution of CC, CO, and –OH based on the UV–Vis and FTIR test. The formation of a complex compound of Fe-(NH4Cl-RHA)n blocks the corrosion active sites to reduce the corrosion. This study paves the way for using RHA as an organic compound under NH4Cl conditions, such as in a refinery process facility.

In this study was examined the response of carbon steel to atmospheric corrosion after one-year exposure in Valle de Aburrá, a subregion located in northwestern Colombia. The study involved the assessment of material mass loss and corrosion rate, the characterization of atmospheric aggressiveness, and the analysis of the morphology and composition of corrosion products in five different sites. Climatological and meteorological factors were assessed by testing for chloride content, sulfur dioxide levels, and time of wetness (TOW). The analysis of corrosion products was conducted using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy. Based on corrosion rates, two sites exhibited a more aggressive environment, with a corrosivity category of C3, while the remaining sites were categorized as C2. The study confirmed the presence of lepidocrocite and goethite phases on the surface of carbon steel at all test sites. Data analysis revealed that both the TOW and the industrial activity significantly influence the corrosion of this metal.

The power semiconductor joining technology through sintering of copper nanoparticles is well-suited for die attachment in wide bandgap (WBG) semiconductors, offering high electrical, thermal, and mechanical performances. However, sintered nanocopper will be prone to degradation resulting from corrosion in sulfur-containing corrosive environments such as offshore areas. In this study, experiments, including aging test and corrosion characterization, and simulations based on density functional theory (DFT) studies were conducted to explore the corrosion behavior and mechanism of elemental sulfur (S8) and hydrogen sulfide (H2S) on sintered nanocopper. The experimental results indicated that loose corrosion products were observed on the sintered nanocopper during the ageing process involving S8, and compact layered corrosion products formed during the ageing process involving H2S. Furthermore, similar corrosion product compositions (Cu2O, Cu2S, CuO, CuS, and potentially Cu2SO4 or CuSO4) were observed in both the S8- and H2S-ageing processes. However, the S8-ageing process exhibited more noticeable corrosion penetration. This was explained in simulations results: the unsaturated Cu sites on the oxide layer [Cu2O(111)] of the sintered nanocopper could adsorb both H2S and S8, while the saturated Cu sites only exhibited the potential to adsorb S8.

The Colossus of San Carlo Borromeo, named San Carlone for its large dimensions, represents a unique opportunity to study the long-term effects of atmospheric corrosion on patina formation on historic copper sheets. The sculpture’s large dimensions, complex geometry, direct visitor interaction, and exposure conditions generate different microclimates. The purpose of this study is to understand how and to what extent these microclimates affect the formation of the copper patinas. The results show that microclimates play a key role in patina formation: in external surfaces exposed to rain, the main constituent is brochantite, whereas a wider variety of corrosion products have been found in sheltered and internal surfaces, such as antlerite, atacamite, copper oxalate, posnjakite, and anglesite.

The time-dependent degradation of galvanised steel bolts subjected to marine atmospheric exposure for a maximum period of 2 years in the Wenchang marine environment of Hainan province, South China, was investigated. The results showed that the zinc coating used as a protective surface finish deteriorated quickly due to the harsh environmental conditions. The deterioration of the zinc coating resulted in premature corrosion of the underlying steel substrate as early as 6 months. The main Zn corrosion products found at the initial exposure time were simonkollite (Zn5(OH)8Cl2·H2O), hydrozincite (Zn5(OH)6(CO3)2), and zincite (ZnO). At subsequent exposure times, major steel corrosion products such as lepidocrocite (γ-FeOOH), akaganeite (β-FeOOH), goethite (α-FeOOH), magnetite (Fe3O4), and maghemite (γ-Fe2O3) were detected. Fe3O4/γ-Fe2O3 was consistently found in the rust formed at both the exposed and crevice thread regions between 6 and 24 months of exposure. Based on the geometry of the bolt fastener, the corrosion rate and phase composition distribution varied between the two regions. Differences in oxygen exposure levels, corrosion kinetics, and electrochemical stability of the corrosion products were primary factors in these distinctive corrosion behaviours.

The Colossus of San Carlo Borromeo, named San Carlone for its large dimensions, represents a unique opportunity to study the long-term effects of atmospheric corrosion on patina formation on historic copper sheets. The sculpture's large dimensions, complex geometry, direct visitor interaction, and exposure conditions generate different microclimates. The purpose of this study is to understand how and to what extent these microclimates affect the formation of the copper patinas. The results show that microclimates play a key role in patina formation: in external surfaces exposed to rain, the main constituent is brochantite, whereas a wider variety of corrosion products have been found in sheltered and internal surfaces, such as antlerite, atacamite, copper oxalate, posnjakite, and anglesite. [ABSTRACT FROM AUTHOR]

This study delves into the atmospheric corrosion behavior of chromium-free complex-phase (CP) steel, specifically investigating the influence of wet/dry frequency and ratio in cyclic corrosion tests (CCT). The study employs a modified ISO 14993 standard CCT method, which involves salt spray, dry, and wet stages. After 15 and 30 CCT cycles, mass loss, maximum corrosion depth, and corrosion products were analyzed to gain insights into corrosion mechanisms. In general, increasing the frequency and wet/dry stage ratio in CCT extends the time for autocatalytic reactions to occur, leading to accelerated localized CP steel corrosion and increased pitting factors. However, as the rust layer thickens, uniform corrosion may also intensify, so careful considerations are necessary. This study underscores the importance of controlling the frequency and ratio of wet/dry stages in CCT for effectively analyzing localized corrosion behavior in specimens. [ABSTRACT FROM AUTHOR]

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 wheat ship unloader in the harbour of Port Louis, in Mauritius, is facing corrosion problems. The atmospheric corrosion rate in Port Louis was found to fall in the category C4 according to ISO 9223. The main corrosion issue of the ship unloader relates to the high maintenance cost resulting from painting problems. Hence, this study was performed to determine the parts of the ship unloader most prone to corrosion through a corrosion risk assessment. The steps involved in the corrosion risk assessment include undertaking a criticality appraisal and determining the associated risk. Hence, the criteria for the Severity, Occurrence and Criticality of corrosion were defined. The risk rating for all the operating units, equipment and systems was determined. The components and subcomponents of the wheat ship unloader were studied thoroughly to categorise the corroded parts in order of priority. Solutions were proposed to decrease the cost of maintenance and the corrosion cost of the ship unloader as well as other similar structures. [ABSTRACT FROM AUTHOR]

Since testing organic coatings under natural conditions is a time‐consuming process, accelerated methods are needed to produce results in less time. A simulated environment cannot fully reproduce actual operating conditions, so it is important to investigate the correlation between accelerated and natural aging test results. In this article, the natural aging of painted steel, aluminum, and hot‐dip galvanized steel is studied for 1 year under continental climate conditions. The environmental parameters responsible for the change of the protective system in a continental urban environment were monitored: time of wetness, ultraviolet radiation, and temperature. The extent of deterioration is compared with similar samples weathered by accelerated testing using electrochemical impedance spectroscopy, differential scanning calorimetry, and gloss measurements. Neutral salt spray chamber, prohesion test, immersion in a quiescent salt solution, and ultraviolet B‐rays (UVB) exposure test are considered. The results of the accelerated cabinet tests are discussed, and the effect is evaluated for the various coated metals. This study highlights the major problems encountered in building a model to predict durability in such a critical area as the durability of organic coatings for metal structures. [ABSTRACT FROM AUTHOR]

Four 1-year tests of metal samples (carbon steel, zinc, copper, aluminum, and D16 alloy) were carried out at locations with coastal and rural atmospheres to determine corrosion losses and the rate of chloride deposition ([Cl-]) on the upper and lower sample sides. [Cl-] were determined for different orientations relative to the sea winds on coastal sites. A methodology for testing metal samples is presented and the values of the first-year corrosion losses of metals (C1) are reported. It is shown that the corrosion of metals is significantly affected by the season of when the samples are installed. The atmosphere corrosivity under each conditions of sample exposure is estimated by the C1 values calculated using the developed dose-response functions (DRFs). It has been shown that the DRFs can be used to predict C1 and estimate the atmosphere corrosivity categories at locations with various types of atmosphere and under various exposure conditions. [ABSTRACT FROM AUTHOR]

To accelerate the formation of the protective rust layer on weathering steel, a new pre-corrosion method containing a replacement reaction was explored. This process was mixed with Cu in the pre-corrosion rust layer to imitate the enrichment of alloying elements through long-term corrosion. By using various analysis methods, the initial corrosion behavior of weathering steel and carbon steel with/without pre-corrosion treatment was studied under indoor wet-dry cycle conditions. The results showed that the pre-corrosion treatment covers the steel surface with a rust layer containing high-concentration Cu. Subsequently, the corrosion uniformity of the weathering steel was significantly improved, and the protective performance of corrosion products was enhanced due to the high concentration of Cu enrichment. This technology is expected to provide a new way to perfect the service performance of weathering steel at the initial stage of application.

Aluminum alloy structural materials are widely subjected to the interactive effect of atmospheric corrosion under thin liquid film and elastic stress during the actual service. This study utilized the real marine atmospheric environment as the corrosion environment of thin liquid film for 7A04 aluminum alloy, and the specially designed outdoor device was used to apply varying levels of static elastic tensile stress at the same time, and then the corrosion damage behavior of 7A04 alloy under the interactive effect was studied. The research indicates that the 7A04 alloy suffers from pitting and exfoliation corrosion under the test conditions. The applied elastic tensile stress can accelerate the corrosion damage process of 7A04 alloy, and the degree of acceleration increases with increasing stress levels and exposure time. Moreover, the applied stress can also significantly accelerate the deterioration of the mechanical properties of 7A04 alloy, which has a more prominent effect on the elongation after fracture. Additionally, the corrosion mechanism of 7A04 alloy under the interactive effect was also discussed in this paper.

The initial atmospheric corrosion of ZM (ZnAlMg)-coated steel in humid air (85% RH) and humid argon (85% RH) containing 320 ppb SO2 was studied using in situ infrared reflection absorption spectroscopy (IRRAS), FTIR-ATR focal plane array (FPA) imaging and SEM-EDS. The corrosion products formed in humid air containing SO2 are mainly composed of magnesium sulphites and sulphates, with sulphite-containing corrosion products formed initially while the contribution from sulphates increased with exposure time. The results from FTIR-FPA imaging and SEM-EDS showed that the magnesium sulphite and sulphate are formed mainly on eutectic phases with a higher quantity of corrosion products formed on the binary eutectic (Zn-MgZn2) phases. This is due to presence of microgalvanic elements with the zinc-rich phases as the main sites for the cathodic oxygen reduction while the anodic reactions take place on the eutectic areas. Sulphate content is the highest on the binary eutectic phases, due to the microgalvanic effects and the production of oxidants by the cathodic reaction, which increases the oxidation of sulphite to sulphate.

Corrosion is a major cause of early failure in palm oil mill infrastructure in Aceh, Indonesia. Therefore, the aim of this study is to analyze the corrosion rate of steel used in the palm oil mill industry and determine the remaining life of the steel. Round bars and plates made of steel were used as exposure samples. This sample was cleaned of impurities and ground with sandpaper to obtain a 600 grating, then washed with clean water and rinsed with strong liquid, then presented to the climate at the PTPN 1 Tanjung Seumantoh palm oil mill so that it could see the rate of steel erosion due to corrosion. For exposure, steel specimens are placed on racks, and weight measurements are taken once a month to determine corrosion rate values using the ASTM G50 standard. In addition, steel thickness measurements were also carried out in 2021 and 2022 to calculate the corrosion rate using the Standard API 570 standard. Research results of the remaining life of the pipe on the wall tube is about 32 years. the remaining life for the generating pipe is about 29 years, and the remaining life for the heater pipe is about 11 years. from the calculation results obtained the longest remaining life is obtained on the wall pipe while the shortest remaining life of the pipe is found in the heater pipe because the pipe is always heated.

The corrosion behavior of Al–Zn coatings on steel sheets in simulating polluted marine atmosphere was systematically evaluated by weight loss tests, potentiodynamic polarization curves, electrochemical impedance spectroscopy, and acid salt spray test. The results demonstrated that the AI-Zn coating produced a passivation film of Al2O3 with good corrosion resistance, forming a thick and dense layer of insoluble corrosion products. In addition, the corrosion products such as Zn5Cl2(OH)8·H2O and NaZn4(SO4)Cl(OH)6•6H2O hindered the diffusion of corrosive substances into the coating and thus inhibited further corrosion.

Urgent action is required to mitigate the severe corrosion of carbon steel in low-latitude regions. The combination of high humidity, temperature, and salinity in these areas significantly accelerates steel corrosion, posing a substantial threat to the service safety of offshore engineering equipment. This study aims to elucidate the atmospheric corrosion mechanisms of 45# steel in low-latitude coastal areas. Samples of 45# steel were exposed to atmospheric conditions over various durations in the following three geographically distinct regions: Guangzhou, Wanning, and the South China Sea. The corrosion rates were calculated using weight loss tracking and potentiodynamic polarization measurements, while surface corrosion products were examined using X-ray diffraction (XRD) tests. The findings indicate a clear correlation between the corrosion rate of 45# steel and the latitude and specific location of the test area, with the highest to lowest rates observed in the South China Sea, Wanning, and Guangzhou, respectively. Similarly, the extent of corrosion rust penetration in defective coatings followed the same order. Moreover, the protection ability index (PAI) calculations revealed that none of the tested samples formed a protective corrosion film.

This article aims to investigate the atmospheric corrosion of carbon steel in a marine environment abundant in hydrogen sulfide (H2S) resulting from the decomposition of Sargassum seaweed. To accomplish this, four sites with varying degrees of impact were chosen along the coast of Martinique. The corrosion rates of steel were evaluated through mass loss measurements. After one year of exposure, the corrosion rates were notably high, particularly in atmospheres rich in Cl− ions and H2S, ranging from 107 µm to 983 µm. Complementing these findings, surface and product morphologies were characterized using scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). These analyses revealed a significant degradation of the corrosion surface in the most affected atmospheres compared to those unaffected by Sargassum seaweed strandings. Lepidocrocite (γFeOOH) was identified as the predominant product regardless of the exposure atmosphere. However, goethite (αFeOOH) was found to be present in atmospheres most impacted by H2S.

Abstract Isfahan, the capital of Iran during the Safavid period (1501–1736 CE), houses the Ali Qapu Palace. It was constructed during the Safavid period to be used as the royal court and a place for settling the affairs of the country. The palace was built in five stages; the final stage was the porch which contains a pool at its centre. The perimeter of the pool is made of white marble, the floor and walls are covered with metal sheets to which the marble is attached. Today, the dry pool is exposed to the urban environment of the metropolis of Isfahan. This study investigates the composition and the corrosion mechanism of the pool using optical microscopy, ICP-OES, SEM–EDS and X-ray diffraction techniques. The results show that the pool’s cover is made of a large number of sheets of copper joined together by copper and lead nails. The forging (cold-working and annealing) method was used to form the sheets. The corrosion products formed on the surface of the copper sheets are copper oxide and copper trihydroxychlorides. The mechanism of corrosion in the metal pool, including copper oxidation, is due to the formation of copper (II) compounds resulting from the reaction with Cl-contaminated airborne particulate matters (dust).

The atmospheric corrosion behavior of Q345NH steel exposed to various coastal distances was investigated in Wenchang, China. The results revealed that with the shortening of the distance from the coast, the amount of chloride ion precipitation increased and the corrosion rate accelerated. After exposure at different locations, the surface conditions and microstructure are widely divergent owing to their unique composition and phase distribution of the rust layer. The high Cl− concentration along the coast promoted the synthesis of β-FeOOH, which favored the synthesis of Fe3O4 in humid environments. Due to the disparity in molar volumes of these phases, the transformation process led to the crack and deterioration of the rust layer.

Additive manufacturing (AM) allows for optimized part design, reducing weight compared to conventional manufacturing. However, the microstructure, surface state, distribution, and size of internal defects (e.g., porosities) are very closely related to the AM fabrication process and post-treatment operations. All these parameters can have a strong impact on the corrosion and fatigue performance of the final component. Thus, the fatigue-corrosion behavior of the 3D-printed (L-PBF) AlSi10Mg aluminum alloy has been investigated. The influence of load sequence (sequential vs. combined) was explored using Wöhler diagrams. Surface roughness and defects in AM materials were examined, and surface treatment was applied to improve surface quality. The machined specimens showed the highest fatigue properties regardless of load sequence by improving both the roughness and removing the contour layer containing the highest density of defect. The impact of corrosion was more pronounced for as-printed specimens as slightly deeper pits were formed, which lowered the fatigue-corrosion life. As discussed, the corrosion, fatigue and fatigue-corrosion mechanisms were strongly related to the local microstructure and existing defects in the AM sample. [ABSTRACT FROM AUTHOR]

We investigate the effect of pure darkness and UV illumination on the corrosion process of 3Ni weathering steels involved in both marine atmospheric environments. The corrosion behavior of 3Ni steel in both environments was assessed by cyclic acceleration experiments, electrochemical measurements, morphological analysis and physical phase analysis. The results show that UV illumination affects the corrosion process through the photovoltaic effect of the corrosion products, with photoelectrons and photo-vacancies participating in the redox reaction between the substrate and the atmospheric environment, thereby affecting the corrosion rate of 3Ni steel, the physical composition of the corrosion products and the denseness of the rust layer. [ABSTRACT FROM AUTHOR]

The initial atmospheric corrosion of ZM (ZnAlMg)-coated steel in humid air (85% RH) and humid argon (85% RH) containing 320 ppb SO2 was studied using in situ infrared reflection absorption spectroscopy (IRRAS), FTIR-ATR focal plane array (FPA) imaging and SEM-EDS. The corrosion products formed in humid air containing SO2 are mainly composed of magnesium sulphites and sulphates, with sulphite-containing corrosion products formed initially while the contribution from sulphates increased with exposure time. The results from FTIR-FPA imaging and SEM-EDS showed that the magnesium sulphite and sulphate are formed mainly on eutectic phases with a higher quantity of corrosion products formed on the binary eutectic (Zn-MgZn2) phases. This is due to presence of microgalvanic elements with the zinc-rich phases as the main sites for the cathodic oxygen reduction while the anodic reactions take place on the eutectic areas. Sulphate content is the highest on the binary eutectic phases, due to the microgalvanic effects and the production of oxidants by the cathodic reaction, which increases the oxidation of sulphite to sulphate. [ABSTRACT FROM AUTHOR]

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