Plasma electrolytic oxidation of AZ31 and AZ91 magnesium alloys: Comparison of coatings formation mechanism

Ракоч, А. Г.; Monakhova, E. P.; Khabibullina, Zukhra V.; Serdechnova, Maria; Blawert, Carsten; Zheludkevich, Mikhail L.; Гладкова, А. А.

doi:10.1016/j.jma.2020.06.002

Cited by 84 publications

(34 citation statements)

References 54 publications

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“…MAO refers to a novel technology for in-situ growth of ceramic oxide film on a valve's metal surface (Al, Mg, Ti, and their alloys) [ 92 , 93 ]. Implementing a MAO strategy can effectively ameliorate the anti-corrosive and biocompatible properties of Mg-based materials and significantly enhance the continued adhesion of MAO coating to the substrate [ 31 , 94 ], its formation mechanism is as follows [ 95 ]: Mg → Mg 2+ + 2e‾ 4OH‾ → O 2 ↑ + 2H 2 O + 4e‾ 2H 2 O → 2H 2 ↑ + O 2 Mg 2+ + 2OH‾ → Mg(OH) 2 ↓ Mg(OH) 2 → MgO↓ + H 2 O 2 Mg + O 2 → 2MgO↓ …”

Section: Surface Modification Of Mg Alloy Stentsmentioning

confidence: 99%

Advances in coatings on magnesium alloys for cardiovascular stents – A review

Zhang

Yang

et al. 2021

Bioactive Materials

105

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Magnesium (Mg) and its alloys, as potential biodegradable materials, have drawn wide attention in the cardiovascular stent field because of their appropriate mechanical properties and biocompatibility. Nevertheless, the occurrence of thrombosis, inflammation, and restenosis of implanted Mg alloy stents caused by their poor corrosion resistance and insufficient endothelialization restrains their anticipated clinical applications. Numerous surface treatment tactics have mainly striven to modify the Mg alloy for inhibiting its degradation rate and enduing it with biological functionality. This review focuses on highlighting and summarizing the latest research progress in functionalized coatings on Mg alloys for cardiovascular stents over the last decade, regarding preparation strategies for metal oxide, metal hydroxide, inorganic nonmetallic, polymer, and their composite coatings; and the performance of these strategies in regulating degradation behavior and biofunction. Potential research direction is also concisely discussed to help guide biological functionalized strategies and inspire further innovations. It is hoped that this review can give assistance to the surface modification of cardiovascular Mg-based stents and promote future advancements in this emerging research field.

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Section: Surface Modification Of Mg Alloy Stentsmentioning

confidence: 99%

Advances in coatings on magnesium alloys for cardiovascular stents – A review

Zhang

Yang

et al. 2021

Bioactive Materials

105

View full text Add to dashboard Cite

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“…Preparation of such coatings is rather complicated with regard to obtained properties since there are plenty of variables associated with the PEO process, such as applied current or voltage, time of preparation, the optimal chemical composition of electrolyte and in the case of unipolar pulsed or AC signal also frequency, the shape of the signal, duty cycle, etc. [26][27][28][29][30][31]. Probably the most negative feature of PEO coatings, despite many efforts, is still their porosity and consequently their limited corrosion stability.…”

Section: Introductionmentioning

confidence: 99%

PEO of AZ31 Mg Alloy: Effect of Electrolyte Phosphate Content and Current Density

Hadzima

Kajánek

Jambor

et al. 2020

Metals

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In this work, the quality of coatings prepared by plasma electrolytic oxidation (PEO) on an AZ31 magnesium alloy were evaluated. This was done by studying the effects of the chemical composition of phosphate-based process electrolytes in combination with different applied current densities on coating thickness, porosity, micro-cracking and corrosion resistance in 0.1 M NaCl. Both processing parameters were studied in four different levels. Mid-term corrosion resistance in 0.1 M NaCl was examined by electrochemical impedance spectroscopy and based on this, corrosion mechanisms were hypothesized. Results of performed experiments showed that the chosen processing parameters and electrolyte composition significantly influenced the morphology and corrosion performance of the prepared PEO coatings. The PEO coating prepared in an electrolyte with 12 g/L Na3PO4·12H2O and using an applied current density 0.05 A/cm2 reached the highest value of polarization resistance. This was more than 11 times higher when compared to the uncoated counterpart.

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“…The high particle velocities and moderate temperatures achieved by HVOF drew a good academic interest towards Mg alloys treatment, as they lead to very dense coatings with outstanding wear behavior and superior bond strengths [ 9 , 10 ]. The Plasma Electrolytic Oxidation (PEO) [ 11 ] method is environmentally friendly, and the treatment is normally performed in aqueous solutions without the addition of toxic compounds. The formation of PEO coatings is possible on almost all cast and wrought magnesium alloys [ 12 , 13 ], with the result of dense coating structures and good corrosion resistance.…”

Section: Introductionmentioning

confidence: 99%

Low-Cost Biobased Coatings for AM60 Magnesium Alloys for Food Contact and Harsh Environment Applications

Mangolini

Lopresti

Conterosito

et al. 2021

IJMS

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Low-cost, environmentally friendly and easily applicable coating for Mg alloys, able to resist in real world conditions, are studied. Coatings already used for other metals (aluminum, steel) and never tested on Mg alloy for its different surface and reactivity were deposited on AM60 magnesium alloys to facilitate their technological applications, also in presence of chemically aggressive conditions. A biobased PA11 powder coating was compared to synthetic silicon-based and polyester coatings, producing lab scale samples, probed by drop deposition tests and dipping in increasingly aggressive, salty, basic and acid solutions, at RT and at higher temperatures. Coatings were analyzed by SEM/EDX to assess their morphology and compositions, by optical and IR-ATR microscopy analyses, before and after the drop tests. Migration analyses from the samples were performed by immersion tests using food simulants followed by ICP-OES analysis of the recovered simulant to explore applications also in the food contact field. A 30 μm thick white lacquer and a 120 μm PA11 coating resulted the best solutions. The thinner siliconic and lacquer coatings, appearing brittle and thin in the SEM analysis, failed some drop and/or dipping test, with damages especially at the edges. The larger thickness is thus the unique solution for edgy or pointy samples. Finally, coffee cups in AM60 alloy were produced, as real word prototypes, with the best performing coatings and tested for both migration by dipping, simulating also real world aging (2 h in acetic acid at 70° and 24 h in hot coffee at 60 °C): PA11 resulted stable in all the tests and no migration of toxic metals was observed, resulting a promising candidate for many real world application in chemically aggressive environments and also food and beverage related applications.

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Plasma electrolytic oxidation of AZ31 and AZ91 magnesium alloys: Comparison of coatings formation mechanism

Cited by 84 publications

References 54 publications

Advances in coatings on magnesium alloys for cardiovascular stents – A review

Advances in coatings on magnesium alloys for cardiovascular stents – A review

PEO of AZ31 Mg Alloy: Effect of Electrolyte Phosphate Content and Current Density

Low-Cost Biobased Coatings for AM60 Magnesium Alloys for Food Contact and Harsh Environment Applications

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