Corrosion behaviour of a 2219 aluminium alloy treated with a chromate conversion coating exposed to a 3.5% NaCl solution

Grilli, Rossana; Baker, Mark; Castle, J. E.; Dunn, B. D.; Watts, John F.

doi:10.1016/j.corsci.2010.12.006

Cited by 30 publications

(12 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…An investigation about formation of coating over AA2024 reveals that the coating has several cracks and detachment over substrate. The coating over enriched copper-rich particles shows some change in formation, as mentioned in [9]. This indicates that alloy elements have a major Conversion coating is widely used for the protection of aluminium alloys [1].…”

Section: Introductionmentioning

confidence: 99%

Growth Kinetics and Structure of Zr4/Cr3 Based Conversion Coating over Aluminium

Thirupathi¹,

Bárczy²,

Lassú³

2016

View full text Add to dashboard Cite

In this study, the structure of Zr4/Cr3 based conversion coating on aluminium alloys was studied by using the Glow Discharge-Optical Emission Spectroscopy (GD-OES) method. Samples were examined before and after exposure to high vacuum. The results revealed that the structure of the coating has two different phases, solute and gelatinous state. The growth kinetics of conversion coating is investigated by considering the thickness of the coating under various immersion times inside the coating bath. The present data suggest that coating growth kinetics has five different states, namely activation, linear growth, limited growth, saturation limit and detachment state. The conversion coating structure over aluminium alloys such as AA2024 and AA6082 was investigated in detail to understand the influence of the substrate in coating formation. The results imply that the formation mechanism strongly depends on alloying elements of the substrate. Conversion layer growth involves dissolution and deposition of ions. It was found that the alloying elements have a slowdown influence on aluminium dissolution. The results imply that high alloyed aluminium tends to form a coating with less thickness and lower Zr-Cr concentration.

show abstract

Section: Introductionmentioning

confidence: 99%

Growth Kinetics and Structure of Zr4/Cr3 Based Conversion Coating over Aluminium

Thirupathi¹,

Bárczy²,

Lassú³

2016

View full text Add to dashboard Cite

show abstract

“…The self-healing process is observed due to the leaching of Cr(VI) ions from the epoxy primer into the electrolyte solution that is subsequently transported to the aluminum substrate leading to repassivation of the chromium oxide layer on the active sites [10,50]. According with the chromium oxide layer, which is formed at the aluminum surface, several steps are involved in the corrosion protection mechanism of this thin oxide layer; this explains its excellent performance in the protection of the metal substrate during Stage IV [7,[51][52][53]. The first step is where the aluminum surface is oxidized:…”

Section: 3stage IV Self-healing/stable Cr(iii) Oxide Layermentioning

confidence: 99%

Probing the degradation mechanism of a Cr(VI) coating/aluminum alloy 2024-T3 system based on dynamic mechanisms and a 2D deterministic-probabilistic approach

Cho

Cubides

Castaneda

2017

Electrochimica Acta

View full text Add to dashboard Cite

Electrochemical impedance spectroscopy (EIS) has been experimentally used to characterize the degradation mechanisms of a multilayered Cr(VI) coating/aluminum alloy 2024-T3 substrate system in 3.5% NaCl solution at low pH. A 2D damage evolution model is proposed to understand the influence of defined elements into the multilayered coating/substrate degradationprocess. The model was developed assuming steady state conditions, while discretization of the model included multilayered stacks such as a topcoat, a primer, and a chromate conversion layer as a pretreatment on an aluminum substrate. The modeling technique was deterministic-stochastic in nature. The deterministic approach was based on a transmission line model that was developed to represent the local impedance for small segments of the system to characterize physicochemical properties inherent to the organic coatings and the transport mechanisms. The randomly generated structures including coating pore distributions are illustrated by stochastic modeling with probability density functions. The quantitative understanding of the degradation mechanism from this 2D model is achieved, and the 2D analysis shows consistent results with experimental conditions over various immersion times.

show abstract

“…Although the ADC6 aluminium alloy has high corrosion resistance, 3 specific environmental conditions may trigger corrosion with extended storage in humid and salty environments. 9 The fundamental corrosion mechanism and its behaviour in Al alloys, particularly wrought products, have been investigated by several researchers. 10 However, a description of the corrosion properties of the associated cast Al alloy (ADC6) is not enough to clearly understand them.…”

Section: Introductionmentioning

confidence: 99%

Corrosion and mechanical properties of cast aluminium alloys

Okayasu

Takeuchi

Shiraishi

2013

International Journal of Cast Metals Research

View full text Add to dashboard Cite

The corrosion and mechanical properties of cast aluminium alloys [ADC6(Al-Mg) and ADC12(AlSi-Cu)] have been investigated. Specifically, cast samples with different microstructural characteristics were produced using two different casting techniques, namely, gravity casting (GC) and heated mould continuous casting (HMC). For ADC6, intergranular corrosion occurs mainly through the eutectic Mg 2 Si and Al 6 (Mn,Fe) phases and the precipitate free zone around the eutectic structures. On the other hand, pitting corrosion in the a-Al phase is the dominant feature for ADC12. Such corrosion characteristics can be interpreted from the material properties (polarisation resistance and electrode potential) of the individual structures, such as the a-Al phase, eutectic a-Al phase and precipitate phase. It also appeared that the extent of corrosion is affected by the size of the microstructure; the ADC6 sample with small second phases has a high corrosion resistance due to the limited area for corrosion. In addition, the higher proportion of solid solution in the a-Al phase of ADC6, arising from the high cooling rate, makes a high corrosion resistance because of the change of electrode potential. A different trend is obtained for ADC12 due to the pitting corrosion, where low corrosion resistance is obtained for the sample with tiny grain. The tensile strength and ductility for both HMC samples (ADC6 and ADC12) are higher than those for the GC equivalents, which is caused by the presence of tiny microstructures and uniform crystal orientation. However, the mechanical properties of HMC samples decrease dramatically during corrosion, although these are still high compared to those of the GC samples without corrosion.

show abstract

Corrosion behaviour of a 2219 aluminium alloy treated with a chromate conversion coating exposed to a 3.5% NaCl solution

Cited by 30 publications

References 27 publications

Growth Kinetics and Structure of Zr4/Cr3 Based Conversion Coating over Aluminium

Growth Kinetics and Structure of Zr4/Cr3 Based Conversion Coating over Aluminium

Probing the degradation mechanism of a Cr(VI) coating/aluminum alloy 2024-T3 system based on dynamic mechanisms and a 2D deterministic-probabilistic approach

Corrosion and mechanical properties of cast aluminium alloys

Contact Info

Product

Resources

About