Corrosion Inhibition of Pure Aluminium and Alloys AA2024-T3 and AA7075-T6 by Cerium(III) and Cerium(IV) Salts

Rodič, Peter; Milošev, Ingrid

doi:10.1149/2.0431603jes

Cited by 90 publications

(71 citation statements)

References 64 publications

(167 reference statements)

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“…The authors showed that most of the OIH coatings developed were for aluminum-based alloys followed by iron-based alloys. Nowadays, the tendency reported for aluminum-based alloys seems to be maintained [215][216][217][218][219][220]. Moreover, in the last decade, considerable attention has been given to the development of advanced and multifunctional OIH sol-gel coating materials.…”

Section: [138]mentioning

confidence: 99%

Hybrid Sol–gel Coatings for Corrosion Mitigation: A Critical Review

Figueira

2020

Polymers

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The corrosion process is a major source of metallic material degradation, particularly in aggressive environments, such as marine ones. Corrosion progression affects the service life of a given metallic structure, which may end in structural failure, leakage, product loss and environmental pollution linked to large financial costs. According to NACE, the annual cost of corrosion worldwide was estimated, in 2016, to be around 3%-4% of the world's gross domestic product. Therefore, the use of methodologies for corrosion mitigation are extremely important. The approaches used can be passive or active. A passive approach is preventive and may be achieved by emplacing a barrier layer, such as a coating that hinders the contact of the metallic substrate with the aggressive environment. An active approach is generally employed when the corrosion is set in. That seeks to reduce the corrosion rate when the protective barrier is already damaged and the aggressive species (i.e., corrosive agents) are in contact with the metallic substrate. In this case, this is more a remediation methodology than a preventive action, such as the use of coatings. The sol-gel synthesis process, over the past few decades, gained remarkable importance in diverse areas of application. Sol-gel allows the combination of inorganic and organic materials in a single-phase and has led to the development of organic-inorganic hybrid (OIH) coatings for several applications, including for corrosion mitigation. This manuscript succinctly reviews the fundamentals of sol-gel concepts and the parameters that influence the processing techniques. The state-of-the-art of the OIH sol-gel coatings reported in the last few years for corrosion protection, are also assessed. Lastly, a brief perspective on the limitations, standing challenges and future perspectives of the field are critically discussed.Polymers 2020, 12, 689 The development of OIH sol-gel coatings, based on siloxanes, for corrosion mitigation, has been widely studied in the last few years [2,31,[36][37][38]. Numerous studies have been conducted since the early 1990s [39,40]. The studies performed showed that siloxanes were effective in mitigating the corrosion processes of different metallic substrates. This development was mainly due to the need for alternative environmentally friend materials and processes to replace the traditional chromium-based pre-treatments. Hexavalent chromium (Cr (VI)) is carcinogenic and shows high environmental toxicity and its use has been forbidden since 2006. However, Cr(VI) based pre-treatments improve the coating adherence to the substrate and are effective corrosion inhibitors [41][42][43] which make its replacement challenging. The use of the sol-gel method to produce OIH coatings for corrosion mitigation suits the main requirements of what should be an environmentally friendly process (i.e., excludes washing stages; it is a waste-free method) and allows one to obtain coatings with high purity and specific pore volumes and surface areas. Since it is a mild synthesis...

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Section: [138]mentioning

confidence: 99%

Hybrid Sol–gel Coatings for Corrosion Mitigation: A Critical Review

Figueira

2020

Polymers

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“…It is known that the deposition of Ce-oxides proceeds at the cathodic sites at the surface which are, in the case of AA7075-T6, Cu-containing intermetallic particles (IMPs). [54][55][56][57][58][59] The fact that no Cu could be identified at the intermetallic particles proves that the deposits of Ce hydroxide/oxide are thicker than is the EDS analysis depth, i.e. several micrometers.…”

Section: Resultsmentioning

confidence: 99%

Self-Healing Effect of Hybrid Sol-Gel Coatings Based on GPTMS, TEOS, SiO₂Nanoparticles and Ce(NO₃)₃Applied on Aluminum Alloy 7075-T6

Tiringer

Durán

Castro

et al. 2018

J. Electrochem. Soc.

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Aluminum alloy AA7075-T6 is most commonly used in the aircraft and automotive industries. Due to the presence of intermetallic particles, AA7075-T6 is susceptible to localized corrosion in chloride solutions. In the present work multilayer hybrid sol-gel coatings, based on silane precursors 3-glycidyloxypropyl(trimethoxysilane) (GPTMS) and tetraethoxysilane (TEOS), were used to protect AA7075-T6 from corrosion. To enrich the barrier properties of the coating, SiO 2 nanoparticles were added to the GPTMS/TEOS sol-gel solution. Inhibition and a self-healing effect were achieved by doping Ce(NO 3 ) 3 in the coating. A multi-layer system was applied on the substrate composed of a first layer doped with Ce(NO 3 ) 3 and the second, undoped sol-gel layer. The addition of cerium increases the lifespan of hybrid sol-gel coating and has a role in self-healing if it is locked within the first layer of the multilayer coating. The self-healing effect was confirmed by immersion of unscribed and scribed coated substrates in 0.1 mol/L NaCl by using the immersion test, electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy with chemical analysis. Due to increasing demand for light-weight metals to reduce fuel consumption and, consequently, CO 2 emission, aluminum alloy AA7075-T6 is very attractive in automotive and aircraft industries. In addition to its low density, its advantages are high strength-to-weight ratio and good mechanical properties.1-3 However, due to the presence of zinc and copper intermetallic particles, AA7075-T6 readily undergoes localized corrosion, which limits its use in more aggressive environments. Chromate conversion coatings (CCCs), which were used for decades as providing the most effective corrosion protection of aluminum alloys, are limited, in the European Union. 4 Many surface treatments have been proposed to replace CCCs, the sol-gel process being one of the most promising and environmentally friendly. [5][6][7][8][9][10][11][12] In hybrid sol-gel coatings, which combine inorganic and organic compounds, the inorganic compound provides mechanical support, while the organic compound adds to flexibility and decreases treatment temperature. 8,[12][13][14][15] Hybrid sol-gel coatings achieve protection of underlying substrate by acting as barrier coatings. Addition of silica nanoparticles (SiO 2 ) into sol-gel coating has been reported to additionally increase the barrier effect by increasing the coating thickness, density and reinforcement. [16][17][18][19][20][21][22][23] Still, if these coatings do not contain corrosion inhibitors they lack the ability to inhibit the corrosion process once it commences, i.e. they do not show active inhibition ability resulting in a self-healing of the coating.To obtain an active corrosion protection, corrosion inhibitors can be incorporated into sol-gel coating. According to Hinton et al., 24,25 4 and insoluble CeO 2 , which acts as a protective barrier to oxygen and lowers the cathodic activity by hindering the ...

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“…Finally, all the studied inhibitors decreased the rate of both the anodic and cathodic processes. Rodič and Milošev (2016) have carried out a study on the inhibition effects of Cerium (III) and Cerium (IV) Salts on pure aluminum and Alloys AA2024-T3 and AA7075-T6 in 0.1 M NaCl. Electrochemical potentiodynamic measurements were used to study inhibition effectiveness of cerium salts.…”

Section: Corrosion Inhibition Of Aluminium Alloysmentioning

confidence: 99%

The effect of corrosion inhibitors on stainless steels and aluminium alloys: A review

Uwiringiyimana¹,

Sylvester²,

Joseph³

et al. 2016

Afr. J. Pure Appl. Chem.

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Corrosion Inhibition of Pure Aluminium and Alloys AA2024-T3 and AA7075-T6 by Cerium(III) and Cerium(IV) Salts

Cited by 90 publications

References 64 publications

Hybrid Sol–gel Coatings for Corrosion Mitigation: A Critical Review

Hybrid Sol–gel Coatings for Corrosion Mitigation: A Critical Review

Self-Healing Effect of Hybrid Sol-Gel Coatings Based on GPTMS, TEOS, SiO₂Nanoparticles and Ce(NO₃)₃Applied on Aluminum Alloy 7075-T6

The effect of corrosion inhibitors on stainless steels and aluminium alloys: A review

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Corrosion Inhibition of Pure Aluminium and Alloys AA2024-T3 and AA7075-T6 by Cerium(III) and Cerium(IV) Salts

Cited by 90 publications

References 64 publications

Hybrid Sol–gel Coatings for Corrosion Mitigation: A Critical Review

Hybrid Sol–gel Coatings for Corrosion Mitigation: A Critical Review

Self-Healing Effect of Hybrid Sol-Gel Coatings Based on GPTMS, TEOS, SiO2Nanoparticles and Ce(NO3)3Applied on Aluminum Alloy 7075-T6

The effect of corrosion inhibitors on stainless steels and aluminium alloys: A review

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Self-Healing Effect of Hybrid Sol-Gel Coatings Based on GPTMS, TEOS, SiO₂Nanoparticles and Ce(NO₃)₃Applied on Aluminum Alloy 7075-T6