The mechanism of formation of composite microarc coatings on aluminum alloys

Ракоч, А. Г.; Гладкова, А. А.; Kovalev, V. L.; Seferyan, A. G.

doi:10.1134/s2070205113070125

Cited by 3 publications

(2 citation statements)

References 3 publications

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“…Thus, alloying elements in the substrate play a crucial role during the formation of the oxide coating and hence affect the structure of the coating, its composition, and its properties. Generally, PEO coatings on aluminium are comprised of various modifications of alumina (α-, γ-, δ-, η-Al 2 O 3 or amorphous Al 2 O 3 ) [4][5][6]. Further phases also occur, which can include electrolyte components (e.g., mullite from silicate-containing electrolytes) [7][8][9].…”

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

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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: 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

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“…The processes at the interface are governed by many external factors and become even more complicated because of the mutual influence of these factors. Apart from providing the general knowledge about the potential of microarc oxidation, studies of microplasma electrochemical processes [1][2][3][4][5][6][7][8] make it possible to create models of the individual stages of this process.…”

Section: Introductionmentioning

confidence: 99%

Dynamic model of single discharge during microarc oxidation

Нечаев

Popova

2015

Theor Found Chem Eng

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A dynamic model of microdischarge with a mobile liquid cathode was presented. The possibility of electron autoemission was substantiated. It was suggested that the liquid cathode rate be calculated by the Navier-Stokes equation. A scheme that shows the development of a plasma formation depending on the thickness of the coating was given. The objects found on the coating surface and in the sludge were shown to correspond to the model.

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