Morphology, structure, and phase composition of microplasma coatings formed on Al-Cu-Mg alloy

Sonova, A. I.; Terleeva, O. P.

doi:10.1134/s0033173208010098

Cited by 42 publications

(38 citation statements)

References 3 publications

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“…Unfortunately, this issue has not been discussed in detail in the recent reports. [24][25][26] The PEO coatings formed on Al-Cu-Mg alloys had a three-layer structure in the anodic-cathodic mode with asymmetric current as reported by Slonova. 24 Cu, that is used as the alloying element in the substrate has not been founded in ceramic coatings obtained in different solutions.…”

mentioning

confidence: 83%

Effect of the Cu Content on the Microstructure and Corrosion Behavior of PEO Coatings on Al–xCu Alloys

Zhu

Zhang

et al. 2018

J. Electrochem. Soc.

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In this study, scanning electron microscopy and electrochemical techniques were used to investigate the effect of the Cu content on the microstructure and corrosion resistance of plasma electrolytic oxidation (PEO) coatings on Al-xCu alloys. The results showed that Cu in the substrate alloy was used to promote the intensity and the transformation process of the microdischarges, which led to the undulating-ribbon feature of cross-sectional morphologies. The formation of pores and cracks in the coatings was facilitated by the oxygen release due to the oxidation of O 2− and the dissolution of copper oxide. Meanwhile, the average porosity of PEO coatings distinctly increased with the increase in the Cu content, which is the key factor causing the decreased corrosion resistance of PEO coatings. Due to their high strength to weight ratio, Cu-containing aluminum alloys are one of the most promising materials for use in aerospace and automobile applications. However, their application is limited by low corrosion resistance. Therefore, plasma electrolytic oxidation (PEO) is considered to be a well-known process for the in situ production of oxide coatings on Al and its alloys, which can offer better corrosion protection as compared to the other surface modification processes for substrate alloys. [1][2][3][4] In general, many processing factors, such as the composition of electrolyte, 5-7 additives, 8-10 applied power modes, 11-13 electrical parameters, 14,15 temperature, 16 and oxidation time, 17 are used to control the PEO process. These parameters not only affect the PEO process but also the performance of the prepared coatings. The characteristics of the formed PEO coatings could also be affected by the alloying elements in substrate alloys. However, this has not been studied in much detail. To the best of our knowledge, the literature contains several papers that describe the effect of multiple elements (such as Si, Mg, Cu, Li, and Fe) on the properties of the formed PEO coatings for commercial aluminum alloys.18-20 While, only a few studies focused on the effect of single alloying element in substrate. Among others, Ali et al. studied the PEO treatment of simple binary Al-Si alloys and reported that the thickness of PEO coatings significantly decreased, whereas their porosity increased with the increase in the Si content. The decomposition of volatile silicon oxides, such as SiO in the formed coatings during the PEO process, contributed to the high porosity. Furthermore, Si exhibits low electrical conductivity, which adversely affects the formation of microdischarges and the oxidation kinetics of the alloy. 21 Meanwhile, Oh et al. studied the effect of Mg on the properties of PEO coatings on Al-Mg alloys and demonstrated that when the amount of Mg was higher than 3 wt% the formation of α-Al 2 O 3 was inhibited.22 It is also reported that Zn is the primary alloying element for the 7××× series Al alloys, and the peculiar function of Zn during the formation of PEO coatings on binary Al-Zn alloys has also been investig...

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mentioning

confidence: 83%

Effect of the Cu Content on the Microstructure and Corrosion Behavior of PEO Coatings on Al–xCu Alloys

Zhu

Zhang

et al. 2018

J. Electrochem. Soc.

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“…For the ZC alloys, discharges were always of red colour, regardless of the treatment time, possibly due to the presence of copper in the bulk alloy. A voltage transition has been previously observed [20,21] during AC PEO of aluminium and it was assigned to changes in the effective conductivity of discharges [20]. It is not intended here to differentiate between sparks, microarcs, arcs and glow discharges, since, to the authors' knowledge, their identification during PEO is complex [22,23].…”

Section: Voltage-and Current-time Responsesmentioning

confidence: 99%

“…It is considered that, at this stage, the effect of the cathodic component is negligible [20]. After 200-500 s, the voltage signal revealed a characteristic drop of about 120 V for all tested materials.…”

Section: Voltage-and Current-time Responsesmentioning

confidence: 99%

Characterization of AC PEO coatings on magnesium alloys

Arrabal

Matykina

Hashimoto

et al. 2009

Surface and Coatings Technology

325

154

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“…It has been shown that formation of the intermediate layer occurs under a.c. conditions in a micro-arc regime. Under a constant rms current, the regime commences after the initial 15-20 µm of coating has been formed [10,13,14] ; it is manifested by a change of colour and reduction in size of the microdischarges, as well as reduced acoustic emission and changed optical emission, compared to earlier stages of the process. A significant voltage drop occurs when the transition from sparking to micro-arcing is complete.…”

Section: Introductionmentioning

confidence: 98%

“…Such a regime has been termed 'soft' sparking. [13] Although this type of discharge has been long known, [15,16] its nature is not fully understood. Empirical knowledge indicates that 'soft' sparking is promoted by an increased cathodic to anodic current ratio.…”

Section: Introductionmentioning

confidence: 99%

Optimisation of the plasma electrolytic oxidation process efficiency on aluminium

Matykina

Arrabal

Skeldon

et al. 2009

Surface & Interface Analysis

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Plasma electrolytic oxidation (PEO) is a surface treatment technology enabling fabrication of adherent thick (50-150 µm) coatings on light metal alloys with significantly enhanced hardness, wear and corrosion resistance compared with other conventional treatments. The technology has the potential to play a significant role in the transport sector for replacement of steel with light-weight materials of improved durability. A main limitation of PEO lies in its relatively high cost, associated with high energy consumption and low coating efficiency. The present work explores possible routes to improve the process efficiency. It is shown that a combination of conventional pre-anodising with sequential PEO treatment reduces specific energy consumption up to five times because of an increase of the coating growth rate, up to 10 µm/min, compared with existing PEO processes. A further approach to improved coating efficiency involves PEO in electrolytes with suspended fine or nanoparticles, which results in the formation of thicker coatings in reduced time as a result of the incorporation of the particles from the electrolyte into the coating. Additionally, melting of the coating material during the micro-arc discharge process leads to formation of stabilised high-temperature phases, such as tetragonal and cubic zirconia, which provide significantly improved microhardness of the coating material and give a potential for thermal barrier applications.

show abstract

Morphology, structure, and phase composition of microplasma coatings formed on Al-Cu-Mg alloy

Cited by 42 publications

References 3 publications

Effect of the Cu Content on the Microstructure and Corrosion Behavior of PEO Coatings on Al–xCu Alloys

Effect of the Cu Content on the Microstructure and Corrosion Behavior of PEO Coatings on Al–xCu Alloys

Characterization of AC PEO coatings on magnesium alloys

Optimisation of the plasma electrolytic oxidation process efficiency on aluminium

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