Materials and Corrosion-werkstoffe Und Korrosion最新文献

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SEM-EDS analysis of edge section of tube # 9 (Kanthal ® APMT). A type of grain boundary related attack is observed in this specimen. The bright spots correspond to RE elements.

More detailed information can be found in: Maria Asuncion Valiente Bermejo, Alice Moya Núñez, Rikard Norling, Metal loss and corrosion attack of FeCrAl overlay welds on evaporator tube shields of a waste-fi red power plant, Materials and Corrosion 2024, 75, 950.

The bonding strength and LBE corrosion resistance of the Fe15Cr11Al2Si, Fe15Cr11Al0.5Y, and Fe15Cr11Al2Si0.5Y coatings heat-treated at 500–650°C for 500 h were investigated. The results showed that the as-deposited Fe15Cr11Al0.5Y coating has the strongest bonding strength with the F/M steel cladding tube compared with the Fe15Cr11Al2Si and Fe15Cr11Al2Si0.5Y coatings. Heat treatment deteriorates the bonding performance of the coatings, and obvious enrichment of Cr and Al elements appeared. The consumed Al element inside the heat-treated coatings promotes the formation of Fe₃O₄ on the surface of the coatings after the corrosion test. The Y element can inhibit the enrichment of elements and the formation of Fe₃O₄. The bonding strength of the heat-treated coatings can be improved after the corrosion test. The underlying mechanism of the evolution of microstructure and properties of the coatings after heat treatment and corrosion test was discussed.

To meet the application requirements of electronic connectors, a trivalent chromium process (TCP) conversion coating was prepared on the Zn–Ni alloy plating of 2024 aluminium alloy. The composition of the TCP solution was as follows: 45 g/L Cr(NO₃)₃, 14 g/L CoCl₂, 1.3 g/L NiCl₂, 10 g/L citric acid, 10 g/L succinic acid and 1 g/L sodium dodecyl sulphate. The properties of TCP were characterised by a range of techniques, including macroscopic observations, scanning electron microscope, energy-dispersive X-ray spectrometer, three-dimensional (3D) morphometry, electrochemical impedance spectroscopy, polarisation curves and conductivity tests. The TCP prepared in this experiment exhibits a uniform black colour and bright appearance, predominantly composed of Zn, Ni, O, Cr and Co. The TCP enhances the impedance of Zn–Ni alloys, reduces the corrosion current to 1.99 × 10⁻⁵A/cm² and maintains a flatter surface 3D morphology and less surface roughness following electrochemical testing. It has better corrosion resistance. Following the preparation of the TCP on a suitably sized shell sample, the shell resistance was 1.2 mVDC with good electrical conductivity, which meets the requirements for electrical connector applications.

The alloying contents with the same Zn/Ca atomic ratio of 0.13 on the corrosion behavior of Mg-Zn-Ca (ZX) alloys were investigated. The second phases in ZX10, ZX20, ZX30, and ZX51 alloys were identical with a majority of Mg₂Ca and very few Ca₂Mg₆Zn₃ and their distribution changed from isolated to continuous state in ZX30 and ZX51. ZX10 had the lowest corrosion rate of 0.55 mm/year after 168 h immersion in simulated body fluid solution due to the smallest number of sites of galvanic corrosion. The corrosion rate of ZX30 alloy was the highest (0.72 mm/year), while though ZX51 alloy had the most Mg₂Ca, its corrosion rate was reduced to 0.69 mm/year, resulting from the small size and thin Mg₂Ca. In situ microstructure observation demonstrated the high fraction Mg₂Ca phase and continuous Mg₂Ca with bulky size were the main reason for the fast corrosion rate.

The isothermal oxidation behavior of the Cu-11.35Al-3.2Ni-3.5Mn (wt.%) shape-memory alloy (SMA) in the temperature range of 500–900°C in oxygen was studied using the thermogravimetric (TG) method. TG curve showed that the alloy has parabolic isothermal oxidation characteristics. The effect of oxidation on the surface morphology and chemical composition of the Cu–Al–Ni–Mn alloy was determined by scanning electron microscopy, energy-dispersive spectroscopy, and X-ray photoelectron spectroscopy (XPS) analyses. The oxidation rate of SMA increases up to 700°C, remains stable at 800°C, and increases again up to 900°C. The XPS analysis identified that the corrosion products mainly contained MnO₂, MnO/Mn₂O₃, and Al₂O₃.

The corrosion behavior and electrochemical damage mechanisms induced by sulfate-reducing bacteria (SRB) on copper (Cu) were investigated in this study. Electrochemical impedance spectroscopy revealed that SRB accelerated the corrosion of Cu, albeit with a mitigating effect observed due to the formation of a protective and dense biofilm. However, upon the rupture of this protective film, the corrosion tendency of Cu significantly increased. Surface analysis corroborated these findings, with the predominant corrosion product identified as Cu2S, a result further supported by thermodynamic calculations. The accelerated corrosion of Cu was primarily attributed to the physiological metabolism of SRB, which generates hydrogen sulfide as the principal agent driving corrosion processes.

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A multi-layered microstructure of the sulfide scale formed on Al₂₀Co₂₅Cr₂₅Ni₂₅Si₅ high entropy alloy at 900°C and 1 kPa of sulfur partial pressure (a), and corresponding EDS maps of elements distribution in the outer, compact part of the sulfide scale (b).

More detailed information can be found in: Grzegorz Smola, Richard Gawel, Zbigniew Grzesik, Sulfidation behavior of an AlCoCrNiSi high entropy alloy, Materials and Corrosion 2024, 75, 830.