Self-healing Li-Al layered double hydroxide conversion coating modified with aspartic acid for 6N01 Al alloy

Zhang, Caixia; Luo, Xiaohu; Pan, Xinyu; Liao, Liying; Wu, Xiaosong; Liu, Yali

doi:10.1016/j.apsusc.2016.10.034

Cited by 51 publications

(17 citation statements)

References 45 publications

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“…However, one should consider that: (1) in this study the crystallization treatment was prolonged in order to obtain relatively thick coatings, while in the literature very often only a thin conversion layer of LDHs was investigated; (2) the electrolyte employed in this study is more dilute than 3.5 wt % NaCl (0.1 M ≈ 0.58 wt %): for this reason, higher resistance values are expected. Also the parameter R ct for the samples investigated in this study is one of the highest compared to other works reported in the literature (except the LDH reported in [43], which contains vanadates based on corrosion inhibitors). However, also in this case it has to be considered that the electrolyte employed is more dilute compared to the NaCl concentration employed in the studies reported in [44][45][46].…”

Section: Aa6082mentioning

confidence: 61%

“…For this reason, it is not surprising to observe dispersion of the relaxation processes in the investigated frequency range. According to the literature [43,44], the EIS response of the LDH covered samples can be analyzed employing a R s (CPE LDH (R LDH (CPE dl R ct ))) electrical equivalent circuit. In this circuit, R s stands for the resistance of the electrolyte.…”

Section: Aa6082mentioning

confidence: 99%

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Effect of Synthesis Conditions on the Controlled Growth of MgAl–LDH Corrosion Resistance Film: Structure and Corrosion Resistance Properties

Iqbal

Fedel

2019

Coatings

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In this study, a series of MgAl–layered double hydroxide (LDH) thin films were synthesized by a single step hydrothermal process at different synthetic conditions on AA6082, and the combined effect of reaction temperatures and crystallization times on in situ growth MgAl–LDH structural geometry, growth rate, and more importantly on the corresponding corrosive resistance properties are briefly discussed. The synthesis of LDH was performed at reaction temperatures of 40, 60, 80, and 100 °C, while the treatment time was varied at 12, 18, and 24 h. The as-prepared synthetic coatings were characterized by scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR), while the corresponding corrosion protection efficiency of the developed coating was studied through potentiodynamic polarization studies and electrochemical impedance spectra. The findings demonstrated that extended crystallization time and reaction temperature impart a significant effect on the oriented growth of layered double hydroxide, the surface morphology, and on the film thickness, which had a remarkable influence on the LDH corrosion resistance ability. The LDH coated specimen developed at 100 °C for 18 h reaction time showed a more compact and dense structure compared to the traditional platelet structure obtained at 80 °C for 24 h crystallization time, and interestingly that compact structure exhibited the lowest corrosion current density, up to five orders of magnitude lower than that of bare AA6082.

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Section: Aa6082mentioning

confidence: 61%

Section: Aa6082mentioning

confidence: 99%

Effect of Synthesis Conditions on the Controlled Growth of MgAl–LDH Corrosion Resistance Film: Structure and Corrosion Resistance Properties

Iqbal

Fedel

2019

Coatings

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“…NiAl-LDHs, [35,36], where R s is the resistance of electrolyte, while R LDH describe the NiAl-LDH film resistance with a constant phase element which accounts for the Dielectric properties of the LDH film (CPE LDH ) and R ct represents the charge transfer resistance in parallel with constant phase element (CPE dl ). According to the mathematical representation of a CPE, (i.e., Z CPE = 1/(Q(ωj) α ) the parameters Q and α have been employed to describe the response of the electrodes.…”

Section: The Electrical Equivalent Circuit R S (Cpe Ldh (R Ldh (Cpe Dmentioning

confidence: 99%

Chlorides Entrapment Capability of Various In-Situ Grown NiAl-LDHs: Structural and Corrosion Resistance Properties

et al. 2020

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In this work, various NiAl-LDH thin films, exhibiting specific surface morphologies, were developed directly on aluminum AA 6082 substrate to understand the two main characteristics of layered double hydroxide (LDH), i.e., ion-exchange behavior and barrier properties, which are found to have a significant influence on the LDH corrosion resistance properties. The as-prepared NiAl-LDH films were analyzed through the scanning electronic microscope (SEM), X-ray diffraction (XRD), while the corrosion behavior of the synthesized films was investigated by the electrochemical impedance spectroscopy (EIS) and potentiodynamic curves. The results indicated that NiAl-LDH microcrystals grow in various fashions, from porous relatively flat domains to well-developed platelet structure, with the variation of nickel nitrate to ammonium nitrate salts molar ratios. The LDH structure is observed in all cases and is found to cover the aluminum surface uniformly in the lamellar order. All the developed NiAl-LDHs are found to enhance the corrosion resistance of the aluminum substrate, specifically, a well-developed platelet structure is found to be more effective in chloride adsorptive and entrapment capabilities, which caused higher corrosion resistance compared to other developed NiAl-LDHs. The comparison of the synthesized NiAl-LDH morphologies on their ion-exchange capabilities, barrier effect and their combined effect on corrosion resistance properties is reported.

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“…According to the recent reviews on this topic [40,41], several LDH based coatings were developed by the in-situ method on aluminum alloys and were demonstrated to provide the substrate with improved corrosion protection. The anti-corrosion properties of these compounds are recognized to rely on two factors: (i) the ion-exchange mechanism through which corrosive species as chlorides are entrapped into the LDH structure, being thermodynamically more favored than other species to lay inside the domains [42,43], and (ii) a physical barrier effect that protects the substrate [44,45]. Rare earth elements (in particular, lanthanum) have been successfully employed to modify LDH coatings either synthesized by means of the co-precipitation method [46,47] and synthesized in situ on aluminum alloys [48][49][50][51].…”

Section: Introductionmentioning

confidence: 99%

Insight into the Role of Cerium (III) Addition to a MgAl-LDH Coating on AA6082

Fedel

Zampiccoli

2021

Applied Sciences

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In this work, Ce doped MgAl-LDHs layers have been developed through an in-situ synthesis method on 6082 aluminum surface. The aim was to gain mechanistic insight into the role of Ce(III) as an active corrosion inhibitor embedded in the LDHs layer. The development of the LDH structure was verified by checking the presence of the characteristic XRD peaks, the platelet morphology (evaluated by SEM-EDXS) and the functional groups (by FTIR-ATR analyses). The same techniques were employed to assess the effect of a prolonged immersion time in 0.1 NaCl on the Ce doped MgAl-LDH coatings. Electrochemical impedance spectroscopy (EIS) was employed to monitor the evolution of the electrochemical properties of the coatings during prolonged immersion in saline solutions. The findings suggest a crystallization/dissolution/precipitation mechanism which implies: (i) the formation of crystalline cerium compounds, such as Ce(OH)3, in the LDH structure during the synthesis; (ii) the dissolution upon exposure to the NaCl solution, thus leading to cerium ions release; (iii) the precipitation of amorphous Ce oxides/hydroxides at the cathodic sites when the metal starts to corrode; (iv), the consequent mitigation of the electrochemical activity of the metal and, thus, the reduction of the extent of corrosion.

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Self-healing Li-Al layered double hydroxide conversion coating modified with aspartic acid for 6N01 Al alloy

Cited by 51 publications

References 45 publications

Effect of Synthesis Conditions on the Controlled Growth of MgAl–LDH Corrosion Resistance Film: Structure and Corrosion Resistance Properties

Effect of Synthesis Conditions on the Controlled Growth of MgAl–LDH Corrosion Resistance Film: Structure and Corrosion Resistance Properties

Chlorides Entrapment Capability of Various In-Situ Grown NiAl-LDHs: Structural and Corrosion Resistance Properties

Insight into the Role of Cerium (III) Addition to a MgAl-LDH Coating on AA6082

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