Unmasking chloride attack on the passive film of metals

Zhang, B.; Wang, J.; Wu, Bin; Guo, Xianwei; Wang, Y. J.; Chen, D.; Zhang, Y. C.; Du, Ke; Oguzie, Emeka E.; L., X.

doi:10.1038/s41467-018-04942-x

Cited by 322 publications

(136 citation statements)

References 71 publications

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“…The rupture of the passivation film is caused by the interaction between Cl − ions and the passivation film, and the reaction process is shown in the following equations:

Al {(OH)}_{3} + {Cl}^{-} \to {Al true(OH true)}_{2} Cl + {OH}^{-},

Al {(OH)}_{2} Cl + {Cl}^{-} \to Al {true(OH true) Cl}_{2} + {OH}^{-},

Al true(OH true) {Cl}_{2} + {Cl}^{-} \to Al {Cl}_{3} + {OH}^{-} .

…”

Section: Resultsmentioning

confidence: 99%

Salt‐spray corrosion behavior of a Cu–Al composite plate under AC current

Cheng

Yuan

Huang

et al. 2019

Materials & Corrosion

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Cu–Al composite plate corrosion tests, under a 0–100 A AC current, were conducted for 48 hr in a neutral salt spray. The morphology and corrosion products were studied by scanning electron microscope and X‐ray powder diffraction, through which the effect of the current was analyzed. Meanwhile, the rate and degree of corrosion were evaluated by weight loss, electrochemical and electrolytic conductivity detection methods. The results showed that when the current increased, the corrosion rate initially increased and then decreased. When the current value was 50 A, the corrosion rate was the highest. The corrosion of the Cu–Al composite plate mainly included galvanic corrosion at the interface and pitting on the aluminum matrix, with no corrosion on the copper matrix. The state of the passivation film changed to loose, peeling, rupture, accumulation, compact, and so on when the current value increased. The type of corrosion product was not affected by the current value. The current affects the electromobility of the chloride ions by influencing the conductivity of the corrosion medium. The higher the electromobility of the chloride ions, the less the destruction of the passivation film and as a result, there is a decreased rate and degree of corrosion.

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“…The rupture of the passivation film is caused by the interaction between Cl − ions and the passivation film, and the reaction process is shown in the following equations:

Al {(OH)}_{3} + {Cl}^{-} \to {Al true(OH true)}_{2} Cl + {OH}^{-},

Al {(OH)}_{2} Cl + {Cl}^{-} \to Al {true(OH true) Cl}_{2} + {OH}^{-},

Al true(OH true) {Cl}_{2} + {Cl}^{-} \to Al {Cl}_{3} + {OH}^{-} .

…”

Section: Resultsmentioning

confidence: 99%

Salt‐spray corrosion behavior of a Cu–Al composite plate under AC current

Cheng

Yuan

Huang

et al. 2019

Materials & Corrosion

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“…The possible reasons were the continuous deposition of Cu onto the stainless steel surface to create a barrier for further electrochemical corrosion in wet conditions . However, it has also been reported that chloride ions in the electrolyte can penetrate the surface passive layer, accumulate on the interface between metal and passive film and cause the passivity breakdown, or initiate a break‐down at defective sites such as grain boundaries and nonmetallic inclusion (e.g., MnS) . In the current case of Cu‐bearing steel, chloride ions from the electrolyte may form unstable copper chloride complexes with Cu on the interface of metal substrate and passive film, acting as vulnerable points for the pitting corrosion .…”

Section: Discussionmentioning

confidence: 99%

The Microstructure, Antimicrobial Properties, and Corrosion Resistance of Cu‐Bearing Strip Cast Steel

et al. 2020

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The antimicrobial and corrosion properties of Cu‐bearing steels fabricated via simulated strip casting are examined. Two distinct microstructures are observed: those alloys with Cu concentrations below 5 wt% retain the Cu in solid solution, and those alloys with high Cu concentrations form a two‐phase structure containing an austenite matrix and large Cu‐rich precipitates. The alloys display antimicrobial properties against Escherichia coli, causing up to 65% of bacteria death upon direct contact for 24 h. Surface analysis by X‐ray photoelectron spectroscopy indicates that after exposure to bacteria, the surface passive film remains enriched in Cu and its oxides, and immersion studies confirm gradual release of Cu ions from the passive film in a wet environment. Corrosion testing of the Cu alloys demonstrates that when the copper is retained in solid solution, the corrosion behavior is not markedly different from the copper‐free reference alloy. However, in those higher‐concentration alloys that contain Cu‐rich precipitates, the anticorrosion performance of the steel is greatly deteriorated, with the corrosion mechanism changing from pitting corrosion to selective corrosion.

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“…Furthermore, the noble second phase fall down to form pits when the matrix is dissolved around them for SB ( figure 12(a3), based on figures 6∼7) [45]. As for SF, the corrosion product layer become thicker too bu t the interfaces (in the composite film itself and between film and matrix) would retard the crack propagating in layer ( figure 12(b3), based on figures 6∼7) [44,50]. Finally, the aggressive Cl − would assemble in the cracks and pits more serious, which would result further severe pitting corrosion.…”

Section: Discussionmentioning

confidence: 99%

Microstructure and corrosion behaviors of AZ31 alloy with an amorphous-crystallin nano-composite film

Liu

et al. 2020

Mater. Res. Express

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Magnesium (Mg) alloy has drawn considerable attention for lightweight structural and functional materials, whereas its corrosion resistance still requires to be enhanced. A new strategy for corrosion resistance has been proposed as making an amorphous-crystalline nano-composite film on Mg alloys. The film as the composition as Al 2 O 3 /GaN with a thickness of 20 nm was prepared on AZ31 Mg alloy by atomic layer deposition. Grazing incidence x-ray diffraction, scanning electron microscopy equipped with energy-dispersive spectroscopy, transmission electron microscopy, x-ray photoelectron spectroscopy, and nano indentation tester have been used to characterize the film in details. It is verified the sample has an amorphous/crystalline/Mg interface structure, and a surface with homogeneous elemental distribution and higher hardness. Neutral salt spray test shows the film changes the corroded mode from pitting corrosion to uniform corrosion. Furthermore, electrochemical measurements indicate that the film would raise E corr (ΔE corr =+0.295 V), drop i corr (about 1/10 times), and make electrical equivalent circuits change from R s (CPE R ct (R L L)) to R s (CR f ) (CPE R ct (R L L)). All evaluations show that better corrosion resistance has been by inducing the amorphouscrystalline nano film. The amorphous layer in the film would make a more homogeneous Cl − distribution in the surface and act as a barrier to block the penetration of corrosion medium in the early stage. During corrosion, the interface between the layers in the film could retard the corrosion crack propagating further. The film would be favorate to form a denser corrosion product layer finally. A more uniform and lower corrosion occurs for AZ31 Mg alloy with this nano-composite film.

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Unmasking chloride attack on the passive film of metals

Cited by 322 publications

References 71 publications

Salt‐spray corrosion behavior of a Cu–Al composite plate under AC current

Salt‐spray corrosion behavior of a Cu–Al composite plate under AC current

The Microstructure, Antimicrobial Properties, and Corrosion Resistance of Cu‐Bearing Strip Cast Steel

Microstructure and corrosion behaviors of AZ31 alloy with an amorphous-crystallin nano-composite film

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