Materials and Corrosion-werkstoffe Und Korrosion最新文献

The sustained growth of energy demands has driven unprecedented expansion in the oil and gas pipeline infrastructure development. However, prolonged operational durations coupled with increasingly hostile environmental conditions have precipitated significant corrosion-induced failures across aging pipeline systems. Conventional pipeline repair methodologies are confronted with challenges, including low efficiency and high cost, constraining their practical application. Herein, carbon fiber (CF)/epoxy composites coating was synthesized, which was employed to enhance the corrosion resistance of steel-based pipelines. Electrochemical impedance spectroscopy and salt spray tests demonstrated that the anticorrosion performance of epoxy coating has been greatly improved with the introduction of CF. Meanwhile, the tensile strength and impact resistance of the CF/epoxy composites coating were substantially improved. The enhancement mechanisms could be attributed to the CF mesh hindering the penetration of corrosive ions and the efficient stress transfer at the interface. The composite coating paves the way for its application in the field of rapid leakage plugging of pipelines.

Self-healing anticorrosion coatings have the potential to significantly reduce the losses caused by metal corrosion. This paper reviews the types of self-healing coatings, focusing on the repair mechanisms of different types of self-healing anticorrosion coatings. It also explores the advantages and disadvantages of different types of self-healing materials. Firstly, the hazards of metal corrosion and the importance of self-healing coatings in the industrial field are introduced. Secondly, the triggering conditions of reversible dynamic bonding and shape memory polymers are summarized, including thermal triggering, light-induced, water triggering, and so on. Thirdly, the characteristics and repair mechanisms of intrinsic self-healing coatings are described in detail. Subsequently, the preparation methods and mechanisms of the extrinsic self-healing anticorrosion coatings have been analyzed on the basis of different triggering conditions. In addition, due to the many shortcomings of a single repair mechanism, this article also explores the repair mechanism of multifunctional self-healing coatings. Finally, the current research status was summarized, and this paper proposes the future development direction of self-healing coatings in practical engineering applications.

High-temperature and high-pressure (HTHP) water serves as a critical heat-exchange and reaction medium in numerous industrial applications. Under these extreme conditions, water exhibits distinct physicochemical properties that significantly elevate the corrosion susceptibility of alloys. This study investigates the mechanisms of oxidative corrosion, electrochemical corrosion, and stress corrosion cracking (SCC) in alloys exposed to HTHP water. From a synergistic perspective, it elucidates how interconnected phenomena—namely, accelerated oxide layer rupture, enhanced ion diffusion, and localized stress concentration—markedly accelerate alloy degradation. The findings reveal that reduced intermolecular hydrogen bonding, increased electrical conductivity, and heightened activity of corrosive ions in HTHP water are critical drivers of corrosion. By analyzing molecular structures and dynamics, it clarifies the complex interplay among HTHP water properties, corrosive ions, electrochemical reactions, and mechanical stress, thereby enhancing the understanding of alloy failure mechanisms. These insights provide a theoretical basis for designing corrosion-resistant materials and equipment.

Critical chloride concentration (C_crit) has been one of the most popular parameters for predicting rebar corrosion initiation in concrete. However, its large discreteness makes prediction challenging. Cyclic potentiodynamic polarization (CPP) and critical pitting temperature (CPT) were thus applied to detect the critical environmental condition for chloride-induced localized corrosion and to find a conservative C_crit with lower discreteness. Results show that increased environmental aggressiveness decreases CPT's mean and minimum values. The discreteness of the CPP curve type and CPT are small when the exposure condition is noncorrosive and very aggressive. A new method based on CPT and CPP curves is then proposed to determine a conservative C_crit. If the exposure condition is harsher than this concentration threshold, the minimum CPT will be lower than ambient temperature and nonnegative CPP curves will occur in repeated scans.

Gas metal arc welding is widely used for joining 6xxx series aluminum alloys due to its productivity and efficiency. However, welding can lead to dissolution and breakdown of intermetallics, especially in high-energy processes, making aluminum alloy joints vulnerable to pitting corrosion. This study used cold metal transfer (CMT) and pulsed cold metal transfer (PCMT) to regulate intermetallic production in the fusion zone. Potentiodynamic corrosion tests showed PCMT joints had higher E_corr and lower I_corr values compared to CMT joints. Micro-arc oxidation (MAO) coated samples recorded higher E_corr and lower I_corr values than uncoated samples. Electrochemical impedance spectroscopy tests confirmed the absence of inductive characteristics in coated samples, indicating no localized corrosion, unlike uncoated samples. Thus, MAO-coated samples demonstrated significant improvement in corrosion resistance compared to uncoated samples.

This paper introduces a self-built loop multiphase flow-accelerated corrosion apparatus that can simultaneously conduct In-Situ electrochemical testing and visualization observation of flow field under various flow state environments. The testing results indicated that environment parameters of pipeline system can be accurately adjusted. The common gas-fluid two-phase flow can be simulated and electrochemical testing data under various field environments is accurate and reliable. This apparatus provides technical support for scientists to investigate the FAC behavior of pipelines in multiphase flow environments.

In this study, the microstructure and corrosion behavior of electrodeposited AlCoCrFeNi medium entropy alloy (MEA) coatings were examined. The coatings were deposited with varied deposition times from 5 to 30 min. It was shown that the composition was significantly impacted by the deposition time, which consequently affected the corrosion behavior. X-ray diffraction analysis revealed that a single-phase face-centered cubic (FCC) coating was formed during deposition. The deposited coating at 20 min exhibited the highest corrosion resistance. The corrosion current density value and corrosion potential value of the deposited coating at 20 min were 3.07 ± 0.80 μA/cm² and −219 ± 0.54 mV, respectively. The coating deposited at 20 min contained a high Al, Ni, and Cr content, resulting in the formation of more stable Al₂O₃, NiO, and Cr₂O₃ oxide layers on the coated surface. These stable oxide layers improved the corrosion resistance of the coating.