Oxide ceramic coatings on aluminium alloys produced by a pulsed bipolar plasma electrolytic oxidation process

Yerokhin, Aleksey; Shatrov, A.; Самсонов, В. И.; Shashkov, P.; Pilkington, A; Leyland, A.; Matthews, A.

doi:10.1016/j.surfcoat.2004.10.147

Cited by 253 publications

(130 citation statements)

References 13 publications

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“…There is only a broad peak in the range of [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] • which can be associated to presence of Al 2 O 3 in amorphous or nano-crystalline form. In contrast, the diffractogram of PEO-LDH-NO 3 shows well-defined peaks at 9.71…”

Section: Resultsmentioning

confidence: 99%

PEO Coatings with Active Protection Based on In-Situ Formed LDH-Nanocontainers

Serdechnova

Mohedano

Kuznetsov

et al. 2016

J. Electrochem. Soc.

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In the present work, for the first time Zn-Al layered double hydroxide (LDH) nanocontainers were grown in-situ on the surface and in the pores of plasma electrolytic oxidation (PEO) layer and then loaded with a corrosion inhibitor to provide active protection. The developed LDH-based conversion process ensures partial sealing of the pores and provides an effective corrosion inhibition on demand leading to increased fault-tolerance and self-healing properties. The structure, morphology and composition of the LDH-sealed PEO coatings on 2024 aluminum alloy were investigated using SEM, TEM/FIB, XRD and GDOES. Electrochemical impedance spectroscopy and scanning vibrating electrode techniques show a remarkable increase in the corrosion resistance and fault tolerance when PEO coating is sealed with a LDH-inhibitor treatment. Plasma electrolytic oxidation (PEO) is an advanced anodizing process which leads to the formation of ceramic-like coatings on the surface of many light alloys. The coatings form on the surface as a result of short-lived micro-discharges at high voltages in low-concentrated eco-friendly electrolytes.1 The oxide layers developed by PEO are usually hard, strongly-adherent to the substrate and confer both corrosion and wear resistance.2 The properties of PEO layers can be tuned for various applications such as biomedical, photocatalytic, thermal and decorative playing with composition of electrolytes and electrical parameters. [3][4][5] In spite of many advantages, the PEO coatings are usually composed of relatively porous layers as a result of discharge breakdowns and gas evolution during the coating growth. Such an intrinsic porosity of the layer often compromises the barrier properties of even relatively thick coatings. Moreover, the pores are larger as the coating thickness increases in many cases. Several attempts have been made to reduce or seal such porosity. Optimization of current/voltage regimes, 6,7 changing the electrolyte composition including systems with particles, 8,9 different post-treatments 10,11 and duplex coatings 12,13 were tried among other strategies. However, in spite of offering certain improvement to the barrier properties, none of these approaches ensures active protection. Without active protection, the acceptance of PEO coatings for many high demanding applications such as aeronautics is limited. In previous works, a post-treatment immersion of PEO coated Mg alloys into inhibitor containing solution was tried to achieve active protection. Ce 3+14 and 8-hydroxyquinoline 15 were used as corrosion inhibitors. Certain active protection effect was reported though the important issues related to uncontrollable release of inhibiting species were not considered.Recently, layered double hydroxides (LDH) have been widely investigated as environmentally-friendly containers for active corrosion protection of metals, in the form of conversion films [16][17][18][19] and as inhibiting pigments being incorporated into the polymer coatings. 20 The LDH particles offer a twofold effect of ab...

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Section: Resultsmentioning

confidence: 99%

PEO Coatings with Active Protection Based on In-Situ Formed LDH-Nanocontainers

Serdechnova

Mohedano

Kuznetsov

et al. 2016

J. Electrochem. Soc.

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Section: Methodsmentioning

confidence: 99%

“…The PEO processing was performed in aqueous electrolyte with parameters presented in Table 1 following the methodology described by different groups and adopted from [19,[25][26][27]. The synthesis of Zn-Al LDH-nitrate (PEO-LDH-NO3) and Zn-Al LDH-vanadate (PEO-LDH-VOx) on the surface of PEO-treated AA2024 were performed according to the methodology previously described [17,19]: (1) PEO-LDH-NO3 was grown in a solution of Zn(NO3)2•6H2O (0.1 M) and NH4NO3 (0.6 M) (pH adjusted to 6.5 using 1% ammonia) under 95 °C for 30 min and (2) vanadate intercalation was performed via anion exchange reaction in a solution of 0.1 M NaVO3 at pH 8.4 (50 °C for 30 min).…”

Section: Methodsmentioning

confidence: 99%

Role of Phase Composition of PEO Coatings on AA2024 for In-Situ LDH Growth

et al. 2017

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Plasma electrolytic oxidation (PEO) is an environmentally friendly anodizing technique leading to the formation of a ceramic-like coatings under high-voltage discharges. Layered double hydroxides (LDHs) were grown directly on γ, α, and amorphous Al 2 O 3 powders, respectively, in order to investigate the phase responsible for in-situ LDH growth on PEO coating. Furthermore, it is shown that LDH growth is limited by the high tortuosity of the PEO layer and the accessibility of Al(OH) − 4 anions from the substrate covered with thin amorphous aluminum oxide, through the pores.

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“…Plasma electrolytic oxidation (PEO) is a technique by which a oxide or other ceramic coating can be grown in-situ on Al, Ti, Mg and many other light metals [5][6][7][8][9][10][11]. In PEO technology, sparks or arc plasma microdischarges in an aqueous solution are used to ionize gaseous media from the solution with the result that complex compounds are synthesized on the metal surface by the plasmachemical interactions.…”

Section: Introductionmentioning

confidence: 99%

“…In PEO technology, sparks or arc plasma microdischarges in an aqueous solution are used to ionize gaseous media from the solution with the result that complex compounds are synthesized on the metal surface by the plasmachemical interactions. It was used, first of all, for the surface hardening and enhancement of the corrosion resistance of Al [5][6][7][8][9] and, more recently, Mg and Ti alloys [10][11][12]. Thus far, it has had limited application to Zr alloys [12,13].…”

Section: Introductionmentioning

confidence: 99%

Plasma Electrolytic Oxidation (PEO) coatings on a zirconium alloy for improved wear and corrosion resistance

Chen

Nie

Northwood

2010

Tribology and Design

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Zr oxide coatings were deposited using plasma electrolytic oxidation (PEO) on Zr-2.5wt%Nb (Zr-2.5Nb) alloy, which is currently used for pressure tubes in the CANDU nuclear reactor. The effects of two PEO processing factors, electrolyte concentration and current density, on the microstructure and properties of the coatings were systematically investigated. The coating morphology and chemical composition were determined using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Potentiodynamic polarization corrosion testing was used to examine the corrosion resistance of the coatings in a dilute aqueous, LiOH solution. Pin-on-disc wear tests were performed under dry and lubricated sliding conditions. SEM was also used to characterize the wear traces on the coated and uncoated surfaces. A 30-day autoclave experiment was carried out to study the corrosion performance of the Zr-2.5Nb substrate, PEO coatings and a commercial autoclaved black oxide coating. Based on the results of this research, recommendations are made as to processing parameters for the production of oxide coatings with improved wear and corrosion resistance.

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Oxide ceramic coatings on aluminium alloys produced by a pulsed bipolar plasma electrolytic oxidation process

Cited by 253 publications

References 13 publications

PEO Coatings with Active Protection Based on In-Situ Formed LDH-Nanocontainers

PEO Coatings with Active Protection Based on In-Situ Formed LDH-Nanocontainers

Role of Phase Composition of PEO Coatings on AA2024 for In-Situ LDH Growth

Plasma Electrolytic Oxidation (PEO) coatings on a zirconium alloy for improved wear and corrosion resistance

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