Materials and Corrosion-werkstoffe Und Korrosion最新文献

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The morphology (SEM image) of the urea-formaldehyde-alkyd resin microcapsules. The microcapsules were regularly globular in shape.

More detailed information can be found in: Bin Xie, Hongwei Shi, Yingwei Song, En-Hou Han, Self-healing polyurethane anticorrosive coatings based on alkyd resin microcapsules, Materials and Corrosion 2024, 75, 1090.

The hot corrosion behavior of two ternary Mo–Si–Ti alloys (eutectic Mo–20.0Si–52.8Ti (at.%) and eutectoid Mo–21.0Si–34.0Ti (at.%)) was investigated at C and C for up to 100 h. Both Mo-based alloys evidenced a hot corrosion attack, resulting in a uniform attack of the substrate surface. The higher Ti content of the eutectic alloy significantly reduced the formation of solid and volatile Mo oxides compared with the eutectoid alloy. After 24 h at C, the corrosion products formed on the eutectic alloy were only one-tenth the thickness of the layers formed on the eutectoid alloy. The corrosion products were examined with optical and electron microscopy. Semiquantitative electron probe micro analysis and X-ray diffraction measurements were used to identify the formed phases. The underlying corrosion mechanisms comprising not only hot corrosion-induced fluxing but also oxidation-induced pesting are discussed in detail.

The stress corrosion behavior of Ti-6Al-3Nb-2Zr-1Mo (Ti6321, in wt%) alloy in seawater with different dissolved oxygen (DO) concentrations was investigated using X-ray photoelectron spectroscopy, energy dispersive spectrometer, electrochemical measurements, and other advanced methodologies. The results indicate that when the DO concentration in seawater is insufficient, the passivation film will preferentially form on the α-phase surface. Meanwhile, insufficient DO concentration leads to incomplete oxidation of the surface passivation film, resulting in an increase in surface defects. Hydrogen produced by reactions at crack tips is more likely to enter the surface of the titanium alloy through these defects, and under the influence of HEDE and HELP mechanisms, promote crack propagation.

To study the corrosion behavior of Zn–Al pseudo alloy coatings with different Al contents, Zn–xAl (x = 19, 27, and 37) pseudo alloy coatings were prepared by the wire arc spraying technique using Zn and Al wires with different diameters. This study investigated the microstructure, electrochemical corrosion behavior, and corrosion morphology and products of the as-sprayed coatings after the salt spray test in 5 wt% NaCl solution. The results exhibited that the Zn–Al pseudo alloy coatings with higher Al content form denser corrosion products (Zn₅(OH)₈Cl₂·H₂O and Zn–Al layered double hydroxide) with stronger self-shielding effect against corrosive media, thus provide better long-term corrosion protection. Besides, electrochemical reactions are controlled by mass transfer until corrosion for 24 h, and then by a combination of mass transfer and diffusion for 96 h. Overall, it can be concluded that the Zn–37Al pseudo alloy coating in this study shows great potential to protect steel substrates from corrosion.

Using polarization curve scanning, electrochemical impedance spectroscopy, macroscopic morphology observation, scanning electron microscope, X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS), the corrosion regulars of connectors were investigated. A galvanic corrosion simulation model of aluminum-titanium rivets was established by electrochemical experimental parameters as boundary conditions. The results showed that the galvanic couple connection accelerated the corrosion significantly. XRD and EDS results show that the main corrosion products are Al₂O_3, Al(OH)₃. The corrosion potential of riveted parts decreased from the riveting point to both sides, ranging from −0.664 to −0.655 V. The corrosion current density decreases along both sides, and the corrosion current density at the most edge is 0.0113 A/m². The results of numerical simulation indicate that the model effectively predicted the galvanic corrosion behavior of aluminum-titanium rivets.

In this work, electrochemical experiments and numerical simulation methods are employed to study the multielectrode galvanic corrosion behavior of 6061-Q235-CFRP, and discuss the influence of the cathode and anode area ratio on the multielectrode galvanic corrosion behavior. The results show that in the 6061-Q235-CFRP multielectrode corrosion system, 6061 aluminum alloy is the only anode, and Q235 as well as CFRP are both cathodes. In a multielectrode galvanic system of 6061-Q235-CFRP, the current density of 6061 is slightly smaller than the sum of the current densities of 6061 in two galvanic systems of 6061-Q235 as well as 6061-CFRP. Moreover, the potential of the galvanic system shifts negatively and the current density decreases gradually with the increasing area of 6061, which has a logarithmic relationship with the area of the cathode and anode. While the current density increases with the increasing area of Q235 or CFRP.

The hot dip aluminized ASTM 1035 steels (Al-coated steel) underwent anodic oxidization, and various thicknesses of Al₂O₃ coating were applied to the surface of the Al-coated steels (Al–Al₂O₃-coated steel). The corrosion resistance of the Al–Al₂O₃-coated steel was investigated using potentiodynamic tests, electrochemical impedance spectroscopy tests and measurement of galvanic current density in a bimetallic cell. It was found that the anodic oxidation resulted in the formation of a porous Al₂O₃ coating on the surface of the Al-coated steel, improving both its corrosion resistance and galvanic corrosion resistance when coupled with carbon fiber reinforced nylon 6 composite (C_f/PA6). Silane treatment effectively sealed the pores within the Al₂O₃ coating, resulting in improved corrosion protection for Al–Al₂O₃-coated steel due to the exceptional insulation, impermeability and hydrophobic properties of silane coating. Compared to the Al-coated steel/carbon fiber reinforced polymer (CFRP) couple and Al–Al₂O₃-coated steel/CFRP couple, stable galvanic current density decreased by approximately 75% and 45%, respectively.