The effect of corrosion inhibiting pigments on environmentally assisted cracking of high strength aluminum alloy

Liu, Xianfei; Huang, Sheng; Gu, Hai

doi:10.1016/s0010-938x(03)00025-8

Cited by 16 publications

(9 citation statements)

References 18 publications

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“…This supposition agrees with the results of previous work on chromate effects on the crack nucleation and early stage crack propagation on AA7XXX alloys exposed to chloride solutions. [68][69][70][71] Chromate was shown to improve the pit-to-crack transition life through slowing the development of pitting corrosion, as well as slow the growth rates of small cracks, attributed to the formation of Cr 3+ -rich films which were posited to act as barrier to hydrogen production and subsequent embrittlement of the crack tip. [68][69][70][71] It should be noted that the results of the present work may be different when extended to complex geometries, such as fastener holes, where the bare noble fasteners and the adjacent corroding Al matrix located far away from the surface may not benefit from the chromate inhibition concentrated at the surface.…”

Section: Discussionmentioning

confidence: 99%

“…[68][69][70][71] Chromate was shown to improve the pit-to-crack transition life through slowing the development of pitting corrosion, as well as slow the growth rates of small cracks, attributed to the formation of Cr 3+ -rich films which were posited to act as barrier to hydrogen production and subsequent embrittlement of the crack tip. [68][69][70][71] It should be noted that the results of the present work may be different when extended to complex geometries, such as fastener holes, where the bare noble fasteners and the adjacent corroding Al matrix located far away from the surface may not benefit from the chromate inhibition concentrated at the surface. In such cases, the growth of any existing corrosion pits or fissures would be sustained by the large cathodic currents provided by the noble fastener, 72,73 thus, accelerating fatigue crack initiation and subsequent crack propagation rates.…”

Section: Discussionmentioning

confidence: 99%

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An RDE Approach to Investigate the Influence of Chromate on the Cathodic Kinetics on 7XXX Series Al Alloys under Simulated Thin Film Electrolytes

Charles-Granville

Liu

Scully

et al. 2020

J. Electrochem. Soc.

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The effect of sodium chromate on the cathodic current availability pertinent to the micro-galvanic-induced corrosion of high-strength AA7XXX alloys under simulated thin electrolyte films representative of atmospheric conditions was investigated utilizing a combination of electrochemical and surface characterization techniques. The rotating disk electrode technique provided a means to simulate the effects of water layer thickness to differentiate thin film conditions from full immersion conditions, and enabled the study of the mass-transport-limited oxygen reduction reaction (ORR) on AA7XXX alloys as a function of chromate concentration. The ORR current density decreased by up to two orders of magnitude upon addition of 10 mM chromate, however, the degree of inhibition was observed to depend on the Cu content of the alloy. Chromate was reduced irreversibly to form a Cr3+-rich film on the alloy surface that blocked cathodic sites and hindered ORR. This film was confirmed by X-ray photoelectron spectroscopic characterization of the chemistry and thickness of the chromate-induced layer formed on the specimens after exposure to chromate. The layer was approximately 13 nm in thickness and consisted of mixed Cr3+/Cr6+ oxides with some metallic Cr. Studies on a Pt electrode demonstrated the intrinsic ability of chromate as an effective inhibitor for ORR.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

An RDE Approach to Investigate the Influence of Chromate on the Cathodic Kinetics on 7XXX Series Al Alloys under Simulated Thin Film Electrolytes

Charles-Granville

Liu

Scully

et al. 2020

J. Electrochem. Soc.

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“…76,77 Possible localized corrosion and pitting can influence the mechanical properties of the material and thus lead to a premature failure through a critical external stress. 78 The significant decrease in failure strain of the HLs with GF40PP composite by about 33.2% can be ascribed to these effects. Figure 7 exhibits a failure location of the composite layer that was completely damaged with the signs of interfacial debonding during the test and the AA7075-O after the tensile test.…”

Section: Tensile Propertiesmentioning

confidence: 94%

Bilayer AA7075-thermoplastic composite structures manufactured by hot pressing: Effect of glass fiber amount of polypropylene composite on mechanical properties

Öztoprak

2023

Journal of Thermoplastic Composite Materials

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This article presents a research into the development of novel Hybrid Laminates (HLs) prepared with the use of hot-pressing method. Two types of HLs are fabricated through the composite coating with different fiber amounts (40 and 50% wt.) of only one surface of 7075-O Al alloy substrate. Effects of the fiber contents of the thermoplastic composite in the hybrid structures are investigated with regards to the tensile and flexural properties. The influence of bending load applied from different surfaces on flexural responses is also evaluated. The tensile test results indicate that the increased fiber ratio slightly affects the failure load of composite layer in the HLs. On the other hand, the flexural strength decreases with the increasing fiber amount in the HLs whether the three-point bending is performed on the Al surface or the composite layer. Scanning electron microscopy (SEM) is used to study the fracture surfaces after the mechanical characterization. From the SEM observations, it has been realized that fiber/matrix debonding is the key failure mechanism during the tensile tests. The failure mode of both HLs is delamination in the PP composite at the tensile side when the bending applied from the Al layer.

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“…Chromates are used in kinds of corrosion prevention coatings including conversion coatings and primers. At the same time, chromate is considered the benchmark for all other corrosion inhibitors to meet so having a comparison point for chromate-free inhibitors would also be beneficial [12], [13]. There have been many research reports on natural products as corrosion inhibitors in different aggressive environments [14][15][16].…”

Section: ‫ي‬ ‫عرض‬mentioning

confidence: 99%

The Corrosion Inhibition Effect on Fatigue Behavior for Aluminum Alloy 5052 in the Saline Environment

Eldwaib,

Aldarwish,

Ballem

et al. 2022

JOPAS

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The corrosion inhibition of Al alloys is the subject of huge technological importance wing to the use of these alloys in wide industrial applications. Fatigue life (number of cycles to failure Nf) for Al-Mg alloy in 3.5% NaCl at different acidity and alkalinity and 3.5% NaCl (pH=1) with inhibitors was investigated in this study. The inhibitors were composed mainly of phosphate, adding a certain proportion of other nontoxic inhibitors to select alternatives to environmentally hazardous chromate. Fatigue behavior was studied by using the corrosion fatigue machine with plane-bending mode. The large difference between the fatigue life in the corrosive mediums, such as NaCl, and that in dry air is noticed. The results showed that in 3.5% NaCl without inhibitor, the minimum fatigue life is obtained at pH=1, where the media is too aggressive (extremely acidic), whereas the highest value is obtained at pH=5 where the very low solubility of oxide film on the alloy. As the concentration of inhibitor increased the number of cycles was increased as well. The scanning electron microscope (SEM) had conducted on the surface morphology and fracture section of the specimens for characterizing.

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The effect of corrosion inhibiting pigments on environmentally assisted cracking of high strength aluminum alloy

Cited by 16 publications

References 18 publications

An RDE Approach to Investigate the Influence of Chromate on the Cathodic Kinetics on 7XXX Series Al Alloys under Simulated Thin Film Electrolytes

An RDE Approach to Investigate the Influence of Chromate on the Cathodic Kinetics on 7XXX Series Al Alloys under Simulated Thin Film Electrolytes

Bilayer AA7075-thermoplastic composite structures manufactured by hot pressing: Effect of glass fiber amount of polypropylene composite on mechanical properties

The Corrosion Inhibition Effect on Fatigue Behavior for Aluminum Alloy 5052 in the Saline Environment

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