Materials and Corrosion-werkstoffe Und Korrosion最新文献

In this study, the Weibull corrosion model and the Winkler subgrade model were combined to investigate the variation of nonlinear corrosion rates and the mechanical performance degradation characteristics of steel pipe piles under different protective layer lifetimes and soil stiffness gradients. A computational tool utilizing the finite difference method was employed to compare the distribution of pile deflection, bending moment, and shear force, and to study the changes in stiffness degradation and lateral bearing capacity behavior over time. Result indicates that the corrosion rate of steel piles gradually accelerates but declines after reaching a peak. Their stiffness also gradually weakens and stabilizes after a rapid loss of stiffness. Due to the increase in soil stiffness gradient, stress concentration in the shallow region of the pile body is continuously exacerbated, causing the location of the peak bending moment within the pile cap at the pile cap to shift significantly upward. It also increases the risk of bending moment concentration in the vicinity. When the soil stiffness gradient increases from 5.0 MN/m⁴ to 10.0 MN/m⁴, the increase in shear force peak is 13.05%. Additionally, extending the service life of the coating can delay the onset of stiffness degradation but accelerates corrosion and stiffness loss in the later stages, with the overall loss remaining essentially unchanged. The findings of this study can offer a practical basis for optimizing offshore monopile design and corrosion protection by revealing the nonlinear impact of corrosion on stiffness and capacity.

This study reports the synthesis and corrosion performance of a non-equiatomic AlCoCrNiMo_0.3 high-entropy alloy (HEA) coating, developed via mechanical alloying and deposited onto SS316 substrates using high-velocity oxy-fuel (HVOF) spraying. X-ray diffraction confirmed the formation of a single-phase body-centered cubic (BCC) solid solution after 20 h of milling, while FESEM-EDS analysis revealed a dense and homogeneously distributed microstructure. Electrochemical characterization in 3.5 wt% NaCl solution demonstrated that the AlCoCrNiMo_0.3 coating exhibited superior corrosion resistance, with a lower corrosion current density (i_corr = 0.45 µA/cm²) and a more noble corrosion potential E_corr = −320 mV versus SCE compared to equiatomic AlCoCrNiMo and WC–CoCr coatings. Post-corrosion analysis confirmed the formation of a Cr/Mo-rich passive layer responsible for localized corrosion inhibition. The optimized Mo addition avoided the formation of brittle secondary phases, maintaining structural integrity. These results establish AlCoCrNiMo_0.3 as a promising candidate for corrosion-resistant coatings in chloride-rich environments.

The high-temperature corrosion behavior of Al_0.3CoCrFeNi and AlCoCrFeNi high-entropy alloys is evaluated at 900°C for 100 h in a Na₂SO₄-25 wt.% K₂SO₄ molten salt environment. Corrosion kinetics are determined through mass change measurements, and the corrosion products are characterized using X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. Electrochemical impedance spectroscopy is employed to investigate corrosion mechanisms and the role of aluminum content. AlCoCrFeNi exhibits significantly lower mass loss, attributed to the formation of a dense, continuous Al₂O₃ scale that inhibits internal oxidation and sulfidation. The presence of Warburg impedance in the EIS spectra indicates a diffusion-controlled process, with Al₂O₃ dissolution acting as the rate-limiting step. In contrast, Al_0.3CoCrFeNi undergoes severe degradation due to oxide layer disruption, driven by molten salt penetration and extensive scale spallation.

High water-cut crude pipelines in undulating terrain face severe corrosion risks, but corrosion probe data often misrepresents actual pipe wall conditions. This study employed laboratory flow loop experiments, corrosion product analysis, and CFD modeling to quantitatively evaluate probe effectiveness. Results show distinct corrosion rate differences between upward/downward pipe walls and internal probes, driven by localized variations in flow velocity, wall shear stress, and turbulent kinetic energy. Based on these mechanisms, a novel correction model was developed specifically for probe monitoring in undulating pipelines. Field validation confirmed the model significantly enhances monitoring accuracy to over 95%, resolving prior unreliability issues. This provides a robust framework and practical tool for improved corrosion rate assessment, critically supporting pipeline integrity management in late-stage oil fields.

The effects of La microalloying on the microstructure and corrosion behavior of as-cast Cu–2.3Ni–0.6Si alloy in 3.5 wt.% NaCl solution were investigated through OM, XRD, SEM, EDS, and an electrochemical workstation. Results indicate that as the La content increased from 0.05 to 0.20 wt.%, the as-cast microstructure of the alloy initially coarsens and subsequently refines. La not only aggregates near the Ni₂Si phase but also induces a preferred crystallographic orientation in in the Cu–2.3Ni–0.6Si alloy. Electrochemical corrosion results demonstrate that Cu–2.3Ni–0.6Si–0.05La exhibits optimal corrosion resistance in 3.5 wt.% NaCl solution, achieving the highest charge transfer resistance (1974 Ω·cm²), the maximum polarization resistance (292.31 kΩ·cm²), and the lowest corrosion current density (1.49 µA·cm⁻²). The improved corrosion resistance is attributed to the combined effects of La's purification role and its promotion of preferential growth of low-index crystallographic planes with high planar density during solidification.

Titanium alloys are susceptible to localized corrosion in fluoride environments. This study compares TiO₂ coatings fabricated by anodic oxidation and magnetron sputtering for corrosion protection. The anodized film is porous and nonuniform; the sputtered TiO_x coating exhibits a dense, nanocrystalline structure (avg. grain: ~62 nm), high adhesion (L_c: 3.85 N), and stable friction coefficient (0.18). Electrochemical tests show the sputtered coating significantly outperforms the anodized film and substrate: lower corrosion current density (0.197 μA·cm⁻²), higher corrosion potential (0.151 V). Under potentostatic conditions (cathode, 0.6 V), it maintains the lowest steady-state current density (0.184 μA·cm⁻²). EIS reveals its charge transfer resistance (5.445 × 10⁵ Ω·cm²) greatly surpasses the anodic film (4.961 × 10³ Ω·cm²) and substrate (2.549 × 10⁴ Ω·cm²), confirming superior corrosion resistance. These findings aid durable coating design for titanium alloys in fluoride-rich acidic media.

This study systematically investigated the effect of Mg content (0.5%, 1.8%, and 3.5%) on the microstructure, mechanical properties, and corrosion behavior of AlSi10 alloys fabricated via selective laser melting (SLM). Microstructural characterization via scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM/EDS) revealed that an increase in Mg content impairs the continuity of the Si network. The most severe disruption is observed in SLM AlSi10Mg3.5, accompanied by Mg aggregation. Tensile tests showed that higher Mg content improved yield strength (up to ~350 MPa in AlSi10Mg3.5) but reduced ductility. Electrochemical tests conducted in 3.5 wt.% NaCl solution demonstrated that SLM AlSi10Mg3.5 has the highest corrosion current density, whereas AlSi10Mg0.5 exhibited the best corrosion resistance. A kinetic model based on the univalent Mg (Mg⁺) was used to interpret the EIS data. Overall, a Mg content of 0.5% achieved an effective balance between mechanical properties and corrosion resistance.

This study aims to enhance the anticorrosion and mechanical performance of epoxy coatings by incorporating tantalum nitride (TaN), zirconium nitride (ZrN), 2-mercaptobenzothiazole (MBT), and graphene oxide (GO) into various nanocomposite formulations. Electrochemical assessments via SECM and EIS demonstrated that the EP/GO/MBT-TaN/ZrN nanocomposite coating provided superior corrosion resistance in seawater, exhibiting a significantly low current density (1.7 nA) and high coating and charge transfer resistances (2.98 × 10¹¹ and 3.57 × 10¹¹ Ω·cm², respectively) after 900 h of immersion. The enhanced performance is attributed to the synergistic effects of the nanomaterials: MBT functionalizes TaN and ZrN nanoparticles via mercapto groups, improving interfacial bonding with the steel substrate and enhancing compatibility with the epoxy matrix, leading to uniform dispersion and reduced porosity. As a result, the EP/GO/MBT-TaN/ZrN coating exhibits excellent adhesion strength (20.4 MPa), hardness (1382 MPa), and hydrophobicity (163°), making it a highly promising candidate for long-term corrosion protection in marine and other harsh industrial environments.