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Strong evidence has been reported on the occurrence of mechanically-assisted crevice corrosion (MACC) between the upper surface of the rail foot and the liner of the fastener, but there is still a lack of attention regarding its effect on materials degradation. A novel testing apparatus was self-developed in this study to simulate the MACC between the rail foot and the liner (disc-on-disc), and a typical rail steel (U75V) and a typical material for the liner (PA66) have been utilized. The fretting regimes, electrochemical behaviors and morphology of the contact surface have been investigated. It has been found that the fretting was mainly controlled by partial slip regime under the condition in this study, and the OCP and anodic current were both increased with increasing fretting frequency and displacement amplitude. The presence of PA66 debris in the form of large spalling particles has been found to inhibit crevice corrosion and relieve the surface damage to some extent. Cracks and local surface collapse were typically noticed on U75V steel which have been ascribed to the accumulation of plastic deformation and the comprehensive effect of fretting wear and corrosion fatigue.

Abstract The appearance of triboelectric nanogenerators (TENG) provides a promising energy technology for harvesting abundant water wave energy. Here, the design and fabrication of a swinging origami‐structured TENG (SO‐TENG) tailored specifically for water wave energy harvesting are presented. The design incorporates an oscillating structure weighted at the bottom, inducing reciprocating motion propelled by the inertia of passing water waves. This reciprocating motion efficiently converts mechanical into electrical energy through the origami structure. By employing origami as the monomer structure, the surface contact area between friction layers is enhanced, thereby optimizing output performance. the swinging structure, combined with the placement of heavy objects, enhances the folding and contact of the origami, allowing it to operate effectively in low‐frequency water wave environments. This configuration exhibits robust power generation capabilities, making it suitable for powering small electronic devices in water wave environments. Furthermore, when applied to metal corrosion protection, the SO‐TENG demonstrates notable efficacy. Compared to exposed Q235 carbon steel, Q235 carbon steel protected by SO‐TENG exhibits a significant reduction in open‐circuit potential drop, approximately 155 mV, indicative of superior anti‐corrosion properties. It lays a solid foundation for water wave energy collection and self‐powered metal corrosion protection in marine environments.

It is well known that the poor corrosion resistance of magnesium alloys is a key factor limiting their application. Field exposure is the most reliable means to evaluate the atmospheric corrosion performance of magnesium alloys. This article reviews the field exposure corrosion behavior of magnesium alloys in typical atmospheric environments (including the marine atmosphere, industrial atmosphere, etc.) in recent years. According to the literature review, it was found that there are significant regional differences in the atmospheric corrosion behavior of magnesium alloys, which is the result of the coupling of multiple factors in the atmospheric environment. By investigating the corrosion rate and corrosion products of different types of magnesium alloys in different environments, the corrosion mechanism of magnesium alloys in different environments was summarized. Specifically, environmental parameters such as atmospheric temperature, relative humidity, CO2, and chloride ion deposition rates in the marine atmospheric environment can affect the corrosion behavior of magnesium alloys. The corrosion of magnesium alloys in different industrial atmospheric environments is mainly affected by atmospheric temperature and relative humidity, as well as atmospheric pollutants (such as SO2, CO2, NO2) and dust. This review provides assistance to the development of new corrosion-resistant magnesium alloys.

Mechanically-assisted crevice corrosion (MACC) is a synergistic combination of wear and crevice corrosion. The major differences between tribocorrosion, fretting corrosion and MACC relate to the relative scale of motion and contact area, are clarified in this work. Experimental testing methods for MACC and design of simulation apparatuses are compared and discussed. MACC associated with biomedical alloys used as orthopedic implants, screws, and dental implants has been the subject of most recent research regarding this corrosion mechanism. However, there are also many engineering structures where the pre-requisite conditions for MACC are met but have to date received less scientific scrutiny. Examples are tubes and supportive bars/plates constructions, bolt-type structures and rail track foot covered by fastening systems. Reasonable selection of fretting-resistant materials, proper mounting methods and development of lubricating coating and oil/grease would be effective for mitigating MACC, and it is proposed that surface modification regarding contact geometries and surface compliances may have future promise.

Pure Zn coatings easily lose their protective performance after biofouling because they have no antibacterial effect under visible light. In this study, we fabricate a new antibacterial Zn composite coating using electrodeposition to couple Fe3+-doped alkalized g-C3N4 (AKCN-Fe) into an existing Zn coating and show that the AKCN-Fe enhances antibacterial property of the Zn coating under visible light. We attribute this enhancement to the high photocatalytic performance, high loading content, and good dispersion of AKCN-Fe. In addition, the photocatalytic antibacterial mechanism of the composite coating is supported by scavenger experiments and electron paramagnetic resonance (EPR) measurements, suggesting that superoxide (·O2−) and hydroxyl radical (·OH) play main and secondary roles, respectively.

Abstract Adherent macrofouling in marine environments caused complex corrosion of steel surfaces, resulting in localized corrosion at the oyster/steel interface and uniform corrosion at the ascidian/steel interface. Sulfate-reducing bacteria (SRB) have been implicated in the microbiologically influenced corrosion (MIC) process at macrofouling-covered interfaces. To better understand the role of marine biofilms as key mediators in the MIC process, metagenomic techniques were used to study microbial communities and their response to macrofouling’s coverage. Compared to ascidians, the formed local anaerobic zone at oyster/steel interface stimulated the growth of SRBs, leading to higher FeS content and severe localized corrosion. SRB Desulfovibrio and Desulfobulbus, along with the SRB-related functional gene dsr, were found to increase, while oxygen-related function genes coxC, ccoN, ccoO, ccoP, and ccoQ decreased. In contrast, steel surfaces without macrofouling coverage had the richest microbial communities, yet experienced less severe MIC, suggesting no direct connection between microbial abundance/diversity and steel corrosion promotion.

The key challenges in aqueous zinc-manganese dioxide batteries (MnO2//Zn) are their poor electrochemical kinetics and stability, which are mainly due to low conductivity and the inevitable dissolution of MnO2. A synergistic combination of a Co-doped σ-MnO2 electrode (Co-MnO2) and a Co(CH3COO)2•4H2O (CoAc) electrolyte additive is here developed to design a high-performance aqueous MnO2//Zn battery (denoted as a Co-MnO2//Zn battery with CoAc). The introduction of Co ions (Co3+/Co2+) into the σ-MnO2 electrode is achieved via a facile one-step electrodeposition method. Benefitting from the synergistic coupling effect of the Co-MnO2 electrode and the CoAc electrolyte additive, the fabricated Co-MnO2//Zn battery with CoAc shows a commendable discharge capacity of 313.8 mAh g−1 at 0.5 A g−1, excellent rate performance, excellent durability over 1000 cycles (∼ 92% capacity retention at 1.0 A g−1) and admirable energy density (439.3 Wh kg−1), which is a significant improvement compared with an un-doped σ-MnO2//Zn battery.

Abstract High-strength steels are widely used in marine engineering; however, they suffer from the risks of corrosion, hydrogen permeation, and stress corrosion cracking (SCC) in wet–dry cyclic marine environments. In this study, the corrosion, hydrogen permeation, and SCC behaviours of AISI 4135 steel in the tidal zone were investigated using electrochemical corrosion, electrochemical hydrogen permeation, and slow strain rate tests, respectively, via field exposure. The results showed that the AISI 4135 steel sample placed at the high tide level had high SCC susceptibility because of severe pitting corrosion and hydrogen permeation, whereas the steel samples placed at the middle and low tide levels had low SCC susceptibilities. The dry/wet time ratio was crucial in determining the SCC behaviour and mechanism of the steel in the tidal zone. With increasing time ratio, the SCC mechanism changed from micro-void coalescence control to localised anodic dissolution and hydrogen embrittlement in tandem.

The corrosion behavior of Mg-Nd binary alloys in the harsh South China Sea environment was researched by scanning electron microscopy, energy-dispersive spectrometry and X-ray diffraction analysis. In order to explain the corrosion mechanism, corrosion resistance was analyzed by weight loss rate and electrochemical measurement in the laboratory. With a continuous enlargement of Nd-content, Mg12Nd phases increased and multiplied. The weight loss rate of Mg-0.5Nd alloy was 0.0436 mg•cm−2•y−1 (0.0837 mm•y−1), whereas that of Mg-1.5Nd alloy was 0.0294 mg•cm−2•y−1 (0.0517 mm•y−1) during the exposure corrosion in the South China Sea site. The mechanical strength of Mg-1.5Nd alloy was 148 MPa before the exposure in the harsh marine environment, while the residual mechanical strength was merely about 94 MPa after the exposure test. Both Mg-1.5Nd alloy and Mg-1.0Nd alloy occurred the brittle fracture, which resulted that the elongation was nearly equal to zero. The self-corrosion current density demonstrated that degradation rate of Mg-Nd binary alloys was as follows : Mg-0.5Nd>Mg-1.0Nd>Mg-1.5Nd. For the South China Sea corrosion site, a large amount of sea salts exited in the atmospheric environment. Due to the heavy rainfall and high humidity, sodium chloride in the atmospheric environment dissolved, more serious electrochemical corrosion occurred on the surface of Mg-Nd binary alloys.

Abstract A vertical contact‐separation mode triboelectric nanogenerator (TENG) to collect mechanical energy and protect stainless steel from corrosion is constructed by spraying to combine MXene powder and polydimethylsiloxane (PDMS). The output of TENG increases significantly by spraying a very small amount (1.2 mg) of MXene, which has excellent conductivity and electro‐negativity. The MXene/PDMS TENG (MP/PP‐TENG) shows the output performance with a short current circuit of 22 µA and output voltage of 900 V, and the output peak power increases by 2.6 times. Meanwhile, MP‐TENG is a reliable alternative to power supply for cathodic protection. The electrochemical measurement results show that the open circuit potential drop of the stainless steel coupled with the MP‐TENG is about 300 mV. Continuous motion of TENG can realize processive protection of metals, proving its potential practical application to all‐weather marine corrosion protection.

The dynamic marine atmospheric corrosion behavior of AZ31 magnesium alloy was investigated in situ exposed on the deck of marine scientific research vessel for 1 year. The marine scientific research vessel carried out five voyages from the coast of China to the western Pacific Ocean, while the navigation track and environmental data were collected and analyzed. The corrosion rate and characteristics were evaluated by using weight loss tests, scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and electrochemical measurements. The corrosion rate from weight loss values was 52.23 μm∙y−1 after exposure for 1 year, which was several times higher than that of the static field exposure test in marine atmospheric environment of other reported literature. The main corrosion products were Mg5(CO3)4(OH)2·4H2O, MgCO3·3H2O and Mg2(OH)3Cl·4H2O. The corrosion was initiated from pitting corrosion and evolved into general corrosion gradually. The serious corrosion maybe due to the harsh corrosive environment with alternating changes in temperature and relative humidity caused by multiple longitude and latitude changes, and particularly high deposition rate of chloride during voyage, which was nearly twenty times that on the coast of China. This study provides effective data for the application of magnesium alloy in shipboard aircraft and other equipment, and provides a reference for indoor simulation experiments.

Hydrogen permeation into high-strength steel during the corrosion process can deteriorate their mechanical properties, thus seriously threatening the safety of steel structures. However, the hydrogen permeation behavior of steels in corrosive marine environments is not well understood. In this study, the hydrogen permeation behavior and mechanism of AISI 4135 steel in different marine corrosion zones was investigated for the first time using an in situ hydrogen permeation monitoring system via outdoor and indoor tests. The three-month outdoor hydrogen permeation test showed that the diffusible hydrogen content of the steels exposed to the marine atmospheric, splash, tidal and immersion zone was 3.15 × 10−3, 7.00 × 10−2, 2.06 × 10−2 and 3.33 × 10−2 wt ppm, respectively. Meanwhile, results showed that the hydrogen permeation current density was positively correlated with the corrosion rate of the steel in the marine environments. This research is of great significance for guiding the safe application of high-strength steel in the marine environments.

Abstract Titanium dioxide (TiO2) nanotube arrays coupled with a narrow gap semiconductor—bismuth selenide (Bi2Se3)—exhibited remarkable enhancement in the photocathodic protection property for 304 stainless steel under visible light. Bi2Se3/TiO2 nanocomposites were successfully synthesized using a simple two-step method, including an electrochemical anodization method for preparing pure TiO2 and a chemical bath deposition method for synthesizing Bi2Se3 nanoflowers. The morphology and structure of the composite films were studied by scanning electron microscopy, energy dispersion spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction. In addition, the influence of the Bi2Se3 content on the photoelectrochemical and photocathodic protection properties of the composite films was also studied. The photocurrent density of the Bi2Se3/TiO2 nanocomposites was significantly higher than that of pure TiO2 under visible light. The sensitizer Bi2Se3 enhanced the efficient separation of the photogenerated electron-hole pairs and the photocathodic protection properties of TiO2. Under visible light illumination, Bi2Se3/TiO2 nanocomposites synthesized by the chemical bath deposition method with Bi3+ (0.5 mmol/L) exhibited the optimal photogenerated cathodic protection performance for 304 stainless steel.

Discovering novel materials and improving the properties of existing materials are the main goals in the field of photocatalysis to increase the potential application of the materials. In this paper, a modified graphitic carbon nitride (g-C3N4) photocatalyst named Fe3+-doped alkalized carbon nitride, which couples the photocatalytic reaction with the Fenton reaction, is introduced to demonstrate its Rhodamine B (RhB) degradation and antibacterial properties. Under visible-light irradiation, the degradation rate of RhB was 99.9% after 200 min, while the antibacterial rates of Pseudomonas aeruginosa (P. aeruginosa), Escherichia coli (E. coli), and Staphylococcus aureus (S. aureus) after 300 min were 99.9986%, 99.9974%, and 99.9876%, respectively. Moreover, the repetitive experiments of RhB degradation demonstrate that the proposed photocatalysts have excellent stability and reusability. The active free radical trapping experiments reveal that the superoxide radical (·O2−) is the dominant reactive oxygen species. In addition, the Fenton reaction is introduced into the photocatalytic system due to the doping of Fe3+, and the hydroxyl radical (·OH) produced from the Fenton reaction further enhances the photocatalytic performance. The remarkable improvement in photocatalytic performance of the proposed photocatalyst can be attributed to its broader UV–visible absorption characteristic and the occurrence of the Fenton reaction.

The key challenges in aqueous zinc-manganese dioxide batteries (MnO2//Zn) are their poor electrochemical kinetics and stability, which are mainly due to low conductivity and the inevitable dissolution of MnO2. A synergistic combination of a Co-doped σ-MnO2 electrode (Co-MnO2) and a Co(CH3COO)2•4H2O (CoAc) electrolyte additive is here developed to design a high-performance aqueous MnO2//Zn battery (denoted as a Co-MnO2//Zn battery with CoAc). The introduction of Co ions (Co3+/Co2+) into the σ-MnO2 electrode is achieved via a facile one-step electrodeposition method. Benefitting from the synergistic coupling effect of the Co-MnO2 electrode and the CoAc electrolyte additive, the fabricated Co-MnO2//Zn battery with CoAc shows a commendable discharge capacity of 313.8 mAh g−1 at 0.5 A g−1, excellent rate performance, excellent durability over 1000 cycles (∼ 92% capacity retention at 1.0 A g−1) and admirable energy density (439.3 Wh kg−1), which is a significant improvement compared with an un-doped σ-MnO2//Zn battery. [ABSTRACT FROM AUTHOR]