An investigation of plasma electrolytic oxidation coatings on crevice surface of AZ31 magnesium alloy

Han, Huiping; Wang, Rui-Qiang; Wu, Ye‐kang; Zhang, Xuzhen; Wang, Dongdong; Yang, Zhong; Su, Yu; Shen, Dejiu; Nash, Philip

doi:10.1016/j.jallcom.2019.152010

Cited by 20 publications

(10 citation statements)

References 57 publications

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“…The reaction mechanism of MgO and Mg 3 (PO 4 ) 2 is shown in eqs and . Mg 2 SiO 4 is formed by the plasma chemical oxidation reaction between the substrate and electrolyte ,− in the discharge channel, as shown in eqs , , and . As shown in Figure , the addition of an appropriate amount of Na 2 SiO 3 to the phosphate electrolyte promotes coating growth and increases the compactness of the coating.…”

Section: Discussionmentioning

confidence: 99%

Preparation and Corrosion Resistance of Microarc Oxidation-Coated Biomedical Mg–Zn–Ca Alloy in the Silicon–Phosphorus-Mixed Electrolyte

2019

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Microarc oxidation (MAO) coating was prepared on the surface of the biomedical Mg–3Zn–0.2Ca alloy in a phosphate electrolyte with varying concentrations of Na2SiO3. The morphology, cross section, chemical composition, and corrosion resistance of the coatings were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), electrochemical polarization tests (EI), and in vitro immersion experiments. The addition of Na2SiO3 is performed to increase the thickness and compactness of the coating. When the Si/P atomic ratio is approximately equal to 1 (1.5 g/L Na2SiO3), the best corrosion resistance is achieved, while excessive addition may lead to coating defects such as voids and microcracks, resulting in decreased corrosion resistance. The competitive relationship between PO43– and SiO32– anions in the silicon–phosphorus microarc oxidation-mixed electrolyte is discussed. In this study, it was first proposed that, when Mg2SiO4 and Mg3 (PO4)2 phase contents were approximately the same, the synergistic improvement effect on coating corrosion resistance was the most effective.

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Section: Discussionmentioning

confidence: 99%

Preparation and Corrosion Resistance of Microarc Oxidation-Coated Biomedical Mg–Zn–Ca Alloy in the Silicon–Phosphorus-Mixed Electrolyte

2019

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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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“…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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An investigation of plasma electrolytic oxidation coatings on crevice surface of AZ31 magnesium alloy

Cited by 20 publications

References 57 publications

Preparation and Corrosion Resistance of Microarc Oxidation-Coated Biomedical Mg–Zn–Ca Alloy in the Silicon–Phosphorus-Mixed Electrolyte

Preparation and Corrosion Resistance of Microarc Oxidation-Coated Biomedical Mg–Zn–Ca Alloy in the Silicon–Phosphorus-Mixed Electrolyte

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

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

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