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Reducing the risks caused by losses due to the atmospheric corrosion of metal structures has been relevant for many years and is an important scientific and technical task. Previously, for this purpose, the preliminary modification of the surface of structural metals with solutions of compositions, based on both individual organosilanes and their mixtures with amine-containing corrosion inhibitors, was proposed. Such treatment leads to the formation of self-assembled siloxane polymeric/oligomeric nanoscale layers on the metal surface, which are capable of changing the physicochemical properties of the metal surface (namely, by reducing the tendency of the metal to corrosive destruction). In this work, annual atmospheric corrosion tests of samples of steel, copper, zinc, and aluminum without protection, and samples modified with compositions based on organosilanes in an urban atmosphere, were carried out. It was established (by the gravimetric method) that the corrosion rate of unmodified (without protection) metals is as follows: steel—0.0022 mm/year; aluminum—0.0015 mm/year; copper—0.00018 mm/year; and zinc—0.00023 mm/year. Using gravimetry and optical microscopy, it was shown that the preliminary modification of metal surfaces with compositions based on organosilanes led to the inhibition of both uniform and local corrosion of metals. The corrosion rates of samples that were modified with one-component compositions decreased by almost two times. The maximum inhibitory effect for the studied systems was demonstrated by mixed binary modifying compositions: mixtures of vinyl- and aminosilane, vinylsilane, and benzotriazole. The corrosion rate decreased for all the studied metals. The minimum effect was observed on zinc (2.5 times) and the maximum inhibition of the corrosion rate was obtained on copper (5.1 times). The mechanism of corrosion inhibition by layers formed as a result of surface modification with two-component mixtures was considered.

Titanium alloys represent a promising material in marine applications, focusing on high-stakes environments where their corrosion resistance and high specific strength offer significant benefits. However, they can still be vulnerable to localized corrosion, such as pitting corrosion and stress corrosion cracking, in the presence of aggressive chlorides. Here we report a lightweight titanium alloy that addresses these issues through conventional casting and thermal-mechanical processing. The alloy can generate a passive film showing distinct but stable electrochemical responses. It is found that the reaction of the passive film can shift from the slow accumulation in the passive region, to the rapid buildup of passive layers in extreme anodic potentials. Consequently, the alloy exhibits a pitting potential above 10 VSCE without being subjected to localized corrosion. Meanwhile, mechanical reliability is also achieved during stress corrosion tests, owing to the fast repair of the passive film that substantially constrains the crack propagation. Such virtual immunity to seawater corrosion qualifies this titanium alloy as a potential candidate for long-term cost savings and sustainability. Seawater corrosion can impact the lifespan and reliability of metallic materials for marine applications. This work develops a titanium alloy exhibiting active passivation behavior that ensures its electrochemical and mechanical stability in seawater-like environments.

In this paper, electrochemical corrosion tests and full immersion corrosion experiments were conducted in seawater at room temperature to investigate the electrochemical corrosion behavior and the corrosion mechanism of high-strength EH47. The polarization curve, EIS (electrochemical impedance spectroscopy), SEM (scanning electron microscope), and EDS analyses were employed to analyze the results of the electrochemical corrosion process. The electrochemical corrosion experiments showed that the open circuit potential of EH47 decreases and then increases with an increase in total immersion time, with the minimum value obtained at 28 days. With an increase in immersion time, the corrosion current density (Icorr) of EH47 steel first decreases and then increases, with the minimum at about 28 days. This 28-day sample also showed the maximum capacitance arc radius, the maximum impedance and the minimum corrosion rate. In the seawater immersion test in the laboratory, the corrosion mechanism of EH47 steel in the initial stage of corrosion is mainly pitting corrosion, accompanied by a small amount of crevice corrosion with increased corrosion time. The corrosion products of EH47 steel after immersion in seawater for 30 days are mainly composed of FeOOH, Fe3O4 and Fe2O3.

Corrosion is frequently viewed as a catastrophic and unavoidable disaster in marine applications. Every year, a huge cost is incurred on the maintenance and repair of corrosion-affected equipment and machinery. In the marine environment, as-cast nickel–aluminium bronze (NAB) is susceptible to selective phase corrosion. To solve this problem, chromium-reinforced nickel–aluminium bronze was fabricated using the friction stir process (FSP) with improved microstructures and surface properties. A slurry erosion–corrosion test on as-cast and FSPed composites demonstrated that the developed surfaced composite has lower erosion and corrosion rates than the as-cast NAB alloy. The erosion–corrosion rate increased with a decrease in the impact angle from 90° to 30° for both as-cast NAB and prepared composites, exhibiting a shear mode of erosion. The specimens at impact angle 30° experienced more pitting action and higher mass loss compared with those at impact angle 90°. Due to increases in the mechanical properties, the FS-processed composite showed higher erosion resistance than the as-cast NAB alloy. Furthermore, corrosion behaviour was also studied via the static immersion corrosion test and electrochemical measurements under 3.5 wt.% NaCl solution. In a static immersion corrosion test, the FSPed composite outperformed the as-cast NAB composite by a wide margin. The FSPed composite also demonstrated a reduced electrochemical corrosion rate, as revealed by the polarization curve and electrochemical impedance spectroscopic (EIS) data. This reduced rate is attributed to the formation of a Cr oxide film over its surface in the corrosive environment.

Corrosion of reinforcement bars in concrete compromises structural integrity and increases maintenance costs. This study investigates the effectiveness of organic (henna powder) and inorganic (zinc powder) corrosion inhibitor coatings in enhancing both corrosion resistance and bond strength retention of coated reinforcement bars embedded in concrete. The significance of the study lies in its approach to measuring the bond strength retention of coated reinforcement bars in a chloride-induced environment. To evaluate the corrosion mitigation and bond strength retention of the coated bars, cylindrical specimens of M20 grade of concrete were cast, having embedded coated and non-coated reinforcement bars having varying coating layers. Accelerated corrosion tests using a 3.5% NaCl solution were applied to cast specimens to simulate aggressive environmental conditions. Bond strength retention was assessed through pull-out tests in accordance with IS 2770: Part 1 (1967). Results showed that reinforcement bars with four coats of henna delayed corrosion initiation by up to 14,525 minutes (~10 days), compared to 6,132 minutes (~5 days) for uncoated bars, representing a 137% improvement in corrosion resistance at 20% corrosion levels. Zinc coatings improved corrosion resistance by up to 65% with four coats at 20% corrosion levels. In bond strength tests, uncoated samples exhibited a 42% reduction in bond strength at 20% corrosion, while henna-coated samples retained up to 90% of their original bond strength, significantly outperforming zinc-coated samples, which retained approximately 84%. The superior performance of henna coatings is attributed to the formation of a protective passive layer containing organic tannins and polyphenolic compounds such as lawsone. Unlike conventional admixture-based or epoxy-based corrosion inhibitors, which are either dispersed within the concrete matrix or applied externally to hardened surfaces, this study pioneers the direct application of henna as a coating on reinforcement bars-targeting corrosion mitigation precisely at the steel–concrete interface without compromising bond strength. These findings highlight the potential of organic inhibitors as cost-effective solutions and present a viable alternative to traditional epoxy-coating-based prevention methods for mitigating reinforcement corrosion while preserving bond strength, offering a promising approach for enhancing the durability of reinforced concrete structures. The study promotes the use of environmentally safe inhibitors to reduce the ecological footprint of reinforced concrete structures and supports the transition toward green and sustainable construction practices.

Magnesium-based alloys presented great potential for biodegradable implant materials. However, the poor mechanical properties and high corrosion rate blocked its extensive application. In this study, a new biodegradable Mg–Zn–Y–Gd–Zr alloy was fabricated and extruded. The microstructure, corrosion morphologies and corrosion products film of the as-cast, homogenized and as-extruded alloys were characterized by optical micrographs, scanning electron microscopy, X-ray diffraction and laser scanning confocal microscopy. Moreover, the corrosion mechanisms of the as-cast and as-extruded alloys were proposed, and the influencing factors of corrosion properties were discussed. The electrochemical test, immersion tests and corrosion morphologies demonstrated that the as-extruded alloy exhibited favorable corrosion properties. The as-cast and homogenized alloys displayed localized corrosion mode, and the as-extruded alloy displayed uniform corrosion mode.The Volta potential of the Mg3(Y,Gd)2Zn3 phase relative to Mg matrix was measured by using Kelvin probe force microscopy.

The C01 type diaphragm coupling demonstrates effective performance in high-concentration seawater salt fog environments. However, the fastener material for this coupling must possess high mechanical properties and strong resistance to seawater corrosion. This study evaluates the suitability of 17−4 precipitation hardening (PH) stainless steel for diaphragm coupling fasteners through a series of tests, including pitting corrosion, crevice corrosion, stress corrosion, fatigue, galvanic corrosion, and cyclic immersion. The results show that the weight loss of 17−4PH stainless steel sample is 13.71% after pitting test and 7.73% after crevice test. However, after stress corrosion, fatigue, and galvanic corrosion tests, the 17−4PH stainless steel sample exhibits minimal corrosion sensitivity. These findings indicate that 17−4PH stainless steel is particularly susceptible to crevice and pitting corrosion. Consequently, 17−4PH shows no pronounced corrosion sensitivity within 15 days of exposure, supporting its provisional use in marine couplings subject to short-term salt fog environments, with caution regarding crevice corrosion risks. 17−4PH is suitable for marine coupling fasteners when combined with passivation, crevice sealing, or design optimization to mitigate pitting and crevice corrosion. Overall, this study provides an experimental basis for the application of 17−4PH stainless steel in diaphragm couplings under high salt fog environments.

This study aims to enhance the corrosion resistance of niobium (Nb)-containing ferritic stainless steel in urea environments within SCR systems. Through urea immersion corrosion tests, we found that as the Nb content increases, both the pitting depth and corrosion rate of the material significantly decrease. The study further revealed that the alkaline environment resulting from urea hydrolysis is the principal cause of stainless steel corrosion. The addition of Nb mitigated the formation of detrimental CrN and Cr 3 C 2 compounds, and elevated the dissolved chromium Cr levels, thereby accelerating the regeneration of the passive film and diminishing the potential for galvanic reactions, ultimately improving the corrosion resistance of the stainless steel.

The aim of this study is to evaluate the effect of titanium on the corrosion characteristics of bridge weathering steel plates in marine environments. The corrosion characteristics of steel containing different Ti additions were studied by simulating marine corrosion by cycles of the dry and wet environments. The addition of appropriate amounts of Ti can promote the production of γ-Fe2O3, which produces a protective rust layer. Steel containing 0.087 wt pct Ti, gave the best results. During long-term dry/wet cyclic corrosion experiments, the corrosion rate of the #0.087Ti steel first accelerated when a protective product layer has not completely covered the surface. The surface of the #0.087Ti steel was only fully covered after 144 hours of testing. With the further extension of periodic immersion testing the corrosion rate began to decrease gradually. After 576 hours of testing a stable protective product layer formed on the #0.087Ti steel, limiting further corrosion.

A dynamic atmospheric corrosion test was carried out with a dedicated test vehicle operating in Harbin, China. Through corrosion kinetic analysis and corrosion product composition analysis, together with electrochemical tests, the corrosion damage behavior of carbon steel after specific periods of exposure was investigated. The corrosion rate of carbon steel showed a gradual decrease with the increase of corrosion time; the rust layer resistance R f and charge transfer resistance R ct gradually increased due to the hindering effect of the dense rust layer and deposition of SiO 2 . Moreover, three hybrid machine learning models, including ABC-SVR, GA-SVR, and PSO-SVR, were constructed to predict the dynamic atmospheric corrosion rate. The results showed that the PSO-SVR algorithm outperforms the GA-SVR and ABC-SVR algorithms, with MAPE = 6.13%, RMSE = 1.11 μm/year, and R 2  = 0.9810.