Microstructure and phase composition of microarc oxidation surface layers formed on aluminium and its alloys 2214-T6 and 7050-T74

Tillous, Kessein Éric; Toll-Duchanoy, T.; Bauer‐Grosse, E.; Héricher, Ludovic; Géandier, Guillaume

doi:10.1016/j.surfcoat.2009.03.021

Cited by 94 publications

(54 citation statements)

References 15 publications

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“…However, it is noticeable that on the AlZn5.5MgCu alloy the peaks for the α-phase are distinctly less pronounced. It can thus be stated that the existence of zinc in the alloy obviously impedes the formation of the α-alumina phase, which is supported by the results of other researchers [10,11]. The results of the EBSD measurement show the distribution of the single phases within the layers and are depicted in Figure 9.…”

Section: Coating Morphology and Compositionsupporting

confidence: 72%

“…Further phases also occur, which can include electrolyte components (e.g., mullite from silicate-containing electrolytes) [7][8][9]. The presence of elements such as Mg, Cu or Zn suppresses the transition from γ-to α-alumina, which again leads to a decreased hardness [10,11]. Nevertheless, all these phases exhibit a significantly higher hardness compared to the substrate [12][13][14] and also compared to oxide coatings produced by anodising or hard-anodising.…”

Section: Introductionmentioning

confidence: 99%

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Plasma Electrolytic Oxidation of High-Strength Aluminium Alloys—Substrate Effect on Wear and Corrosion Performance

Sieber

Simchen

Morgenstern

et al. 2018

Metals

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Abstract:With the progress in materials science and production technology and the establishment of light-weight design in many fields of the industry, the application of light metals no longer requires only mechanical strength, but also a significant protection of the material against wear and corrosion. Hard and wear-resistant oxide coatings on aluminium are produced by plasma electrolytic oxidation (PEO). During PEO, a conversion of the aluminium substrate to a ceramic oxide takes place. While the role of strength-giving alloying elements like Cu, Mg/Si, Zn, and Zn/Cu on the PEO process has selectively been subject of investigation in the past, the significance of the alloy composition for the service properties of the coatings is still unknown. Therefore, the performance of PEO coatings produced on the widely used commercial high-strength alloys AlCu4Mg1 (EN AW-2024), AlMgSi1 (EN AW-6082), and AlZn5.5MgCu (EN AW-7075) is examined with regard to their behaviour in the rubber-wheel test according to ASTM G65 and the current density-potential behaviour of the substrates with undamaged and worn coatings in dilute NaCl solution. To give a reference to the unalloyed material the testings were carried out also on Al 99.5 (EN AW-1050) which was treated in an adjusted PEO process. Although differences in the conversion of intermetallic phases during PEO and the phase composition of the coatings on the various substrates are determined, the service properties are hardly depending on the alloying elements of the investigated aluminium materials. The wear rates in the rubber-wheel test are low for all the alloyed samples. The current density-potential curves show a decrease of the corrosion current density by approximately one order of magnitude compared to the bare substrate. Eventually, previous wear of the coatings does not deteriorate the corrosion behaviour. PEO layers on technically pure aluminum can resist the testing regimes if they are prepared in an electrolyte with an elevated silicate content and without additional hydroxide ions, during a longer process time.

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Section: Coating Morphology and Compositionsupporting

confidence: 72%

Section: Introductionmentioning

confidence: 99%

Plasma Electrolytic Oxidation of High-Strength Aluminium Alloys—Substrate Effect on Wear and Corrosion Performance

Sieber

Simchen

Morgenstern

et al. 2018

Metals

View full text Add to dashboard Cite

show abstract

“…Figure 8c,d illustrates the model of these coatings. It has been proven that excessive gas is released during discharge [39] and that gas might be generated near the substrate/coating interface [9,15]. In this work, cracks or pores would form when high-pressure gases escaped from the molten zone.…”

Section: Growth Model Of Peo Coatingmentioning

confidence: 93%

“…The coating surface is porous and coarse, consisting of pancake-like structures with a central hole [7]. PEO coatings are divided into three layers, i.e., an outer loose layer, an inner dense layer, and the barrier layer near the substrate [8,9]. A free-standing coating detached from the substrate can be used to obtain more information about the PEO coating structure, e.g., the structure of the coating/substrate interface.…”

Section: Introductionmentioning

confidence: 99%

Evolution of the Three-Dimensional Structure and Growth Model of Plasma Electrolytic Oxidation Coatings on 1060 Aluminum Alloy

Liu

Wang

et al. 2018

Coatings

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Abstract:A deeper understanding of plasma electrolytic oxidation (PEO) can in turn shed light on the evolution of coating structures during such oxidation processes. Here, a three-dimensional (3D) structure of PEO coating was investigated based on the morphologies at different locations in a PEO coating and on the elemental distribution along certain sections. The coating surface was dominated by a crater-or pancake-like structure of alumina surrounded by Si-rich nodules. A barrier layer with a thickness of~1 µm consisting of clustered cells was present at the aluminum/coating interface. As the coating thickened, the PEO coating gradually evolved into a distinct three-layer structure, which included a barrier layer, an internal structure with numerous closed holes, and an outer layer with a rough surface. During the PEO process, molten zones formed along with the plasma discharges. The volume and lifetime of the molten zones changed with oxidation time. The diversities of cooling rates around the molten zones resulted in structural differences along a certain section of the coating. A growth and discharge model of PEO coatings was established based on the 3D structure of the particular coating studied herein.

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“…The PEO coatings represent excellent properties, such as high hardness, wear resistance and thermal stability [7] . Unfortunately, the brittleness of these composite oxides ceramic coatings is high and their coefficient of linear expansion has large difference with base metals, therefore, they will easily crack and fall off , which makes base metal lose protection [8] .…”

Section: Introductionmentioning

confidence: 99%

Effects of yttrium ion on formation mechanism of ZrO2-Y2O3 ceramic coatings formed by plasma electrolytic oxidation on Al-12Si alloy

Wang

Guo

et al. 2014

J. Wuhan Univ. Technol.-Mat. Sci. Edit.

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ZrO 2 -Y 2 O 3 ceramic coating was produced by plasma electrolytic oxidation (PEO) on ZAlSil2Cu3Ni2 alloy. The microstructure and phase composition of the coating were investigated by SEM and XRD. The results show that adding an appropriate amount of yttrium ion can improve the growing rate of ceramic coating at different oxidation stages and decrease arc voltage. The thickness of ZrO 2 -Y 2 O 3 coating is 16 μm thicker than that of ZrO 2 coating and the maximum oxidation rate improves by 0.6 μm/min. In addition, the arc voltage decreases from 227 to 172 V. It can be seen that the rate of oxidation fi rstly increases to some extent and then decreases with the content of yttrium ion increasing. The growth rate reaches the maximum while the content of yttrium ion is 0.05 g•L 1 . The maximum thickness is 90 μm.Compared to ZrO 2 coating, the micropores of ZrO 2 -Y 2 O 3 coating are less and the ceramic layer is repeatedly deposited by ZrO 2 and Y 2 O 3 ceramic particles. Meanwhile, the binding force between coating and substrate is better and the coating is uniform and compact. The ceramic layer is mainly composed of c-Y0.15Zr0.85O1.93□0.07, m-ZrO 2 , α-Al 2 O 3 , γ-Al 2 O 3 and Y 2 O 3 . It is indicated that ZrO 2 has been fully stabilized by yttrium ion through the formation of solid solution.

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Microstructure and phase composition of microarc oxidation surface layers formed on aluminium and its alloys 2214-T6 and 7050-T74

Cited by 94 publications

References 15 publications

Plasma Electrolytic Oxidation of High-Strength Aluminium Alloys—Substrate Effect on Wear and Corrosion Performance

Plasma Electrolytic Oxidation of High-Strength Aluminium Alloys—Substrate Effect on Wear and Corrosion Performance

Evolution of the Three-Dimensional Structure and Growth Model of Plasma Electrolytic Oxidation Coatings on 1060 Aluminum Alloy

Effects of yttrium ion on formation mechanism of ZrO2-Y2O3 ceramic coatings formed by plasma electrolytic oxidation on Al-12Si alloy

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