Effect of current density on the microstructure and corrosion properties of plasma electrolytic oxidation (PEO) coatings on AM50 Mg alloy produced in an electrolyte containing clay additives

2016 ◽  
Vol 289 ◽  
pp. 150-164 ◽  
Author(s):  
G. Rapheal ◽  
S. Kumar ◽  
N. Scharnagl ◽  
C. Blawert
Keyword(s):  
Current Density ◽  
Plasma Electrolytic Oxidation ◽  
Mg Alloy ◽  
Corrosion Properties ◽  
Electrolytic Oxidation ◽  
Plasma Electrolytic ◽  
Peo Coatings

Correlation between the Properties of PEO-Layer and Coating Formation Current Density

2020 ◽  
Vol 312 ◽  
pp. 361-365
Author(s):  
Sergey N. Suchkov ◽  
Mariia S. Gerasimenko ◽  
Konstantine V. Nadaraia ◽  
Igor M. Imshinetsky ◽  
Dmitry V. Mashtalyar ◽  
...  
Keyword(s):  
Cross Section ◽  
Current Density ◽  
Plasma Electrolytic Oxidation ◽  
Protective Coatings ◽  
Corrosion Properties ◽  
Electrolytic Oxidation ◽  
Coating Formation ◽  
Current Densities ◽  
Plasma Electrolytic ◽  
Peo Coatings

Presented paper considers the formation of protective coatings on MA8 magnesium alloy by plasma-electrolytic oxidation (PEO). The influence of current densities formation on the structure, corrosion properties of PEO-coatings was studied. Electrochemical and scanning electron microscopy of the surface and cross-section of the samples were carried out. The effect of changing the formation current density on the functional parameters of coatings, such as corrosion resistance, thickness and porosity was investigated.

scholarly journals Bioactivity Performance of Pure Mg after Plasma Electrolytic Oxidation in Silicate-Based Solutions

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 2094
Author(s):  
Yevheniia Husak ◽  
Joanna Michalska ◽  
Oleksandr Oleshko ◽  
Viktoriia Korniienko ◽  
Karlis Grundsteins ◽  
...  
Keyword(s):  
Cell Culture ◽  
Oxide Layer ◽  
Plasma Electrolytic Oxidation ◽  
Oxide Coating ◽  
Mg Alloy ◽  
Aureus Strain ◽  
Active Surface Area ◽  
Corrosion Properties ◽  
Electrolytic Oxidation ◽  
Plasma Electrolytic

The biodegradable metals, including magnesium (Mg), are a convenient alternative to permanent metals but fast uncontrolled corrosion limited wide clinical application. Formation of a barrier coating on Mg alloys could be a successful strategy for the production of a stable external layer that prevents fast corrosion. Our research was aimed to develop an Mg stable oxide coating using plasma electrolytic oxidation (PEO) in silicate-based solutions. 99.9% pure Mg alloy was anodized in electrolytes contained mixtures of sodium silicate and sodium fluoride, calcium hydroxide and sodium hydroxide. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), contact angle (CA), Photoluminescence analysis and immersion tests were performed to assess structural and long-term corrosion properties of the new coating. Biocompatibility and antibacterial potential of the new coating were evaluated using U2OS cell culture and the gram-positive Staphylococcus aureus (S. aureus, strain B 918). PEO provided the formation of a porous oxide layer with relatively high roughness. It was shown that Ca(OH)2 was a crucial compound for oxidation and surface modification of Mg implants, treated with the PEO method. The addition of Ca2+ ions resulted in more intense oxidation of the Mg surface and growth of the oxide layer with a higher active surface area. Cell culture experiments demonstrated appropriate cell adhesion to all investigated coatings with a significantly better proliferation rate for the samples treated in Ca(OH)2-containing electrolyte. In contrast, NaOH-based electrolyte provided more relevant antibacterial effects but did not support cell proliferation. In conclusion, it should be noted that PEO of Mg alloy in silicate baths containing Ca(OH)2 provided the formation of stable biocompatible oxide coatings that could be used in the development of commercial degradable implants.

scholarly journals Influence of Electrolyte Temperature on the Color Values of Black Plasma Electrolytic Oxidation Coatings on AZ31B Mg Alloy

Coatings ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 890
Author(s):  
Aihua Yi ◽  
Zhongmiao Liao ◽  
Wen Zhu ◽  
Zhisheng Zhu ◽  
Wenfang Li ◽  
...  
Keyword(s):  
Plasma Electrolytic Oxidation ◽  
Mg Alloy ◽  
Electrolyte Temperature ◽  
Electrolytic Oxidation ◽  
Key Factor ◽  
Different Temperatures ◽  
Color Value ◽  
Coating Color ◽  
Plasma Electrolytic ◽  
Peo Coatings

A coating was prepared on an AZ31B Mg alloy substrate via black plasma electrolytic oxidation (PEO). The colorant NH4VO3 was added to Na2SiO3–(NaPO3)6 electrolyte at different temperatures (5, 15, 25, and 35 °C). The influences of electrolyte temperature on the structures, compositions, and color values of black PEO coatings were studied by UV–Visible, XRD, XPS, Raman, and SEM techniques. The results showed that the relative content of V2O3 and V2O5 was the key factor affecting the coating color value. At higher temperatures, more NH3 escaped from the electrolyte and the NH3 quantity participating in the reaction decreased, resulting in a decrease of V2O3 content, an increase in color value, and a darker coating. In the PEO process, VO3− mainly reacted to form V2O5, and then, the generated V2O5 reacted with NH3 to form V2O3.

scholarly journals Improvement of Mechanical and Corrosion Properties of Commercially Pure Titanium Using Alumina PEO Coatings

Coatings ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 29
Author(s):  
Viorel Malinovschi ◽  
Alexandru Horia Marin ◽  
Catalin Ducu ◽  
Sorin Moga ◽  
Victor Andrei ◽  
...  
Keyword(s):  
Plasma Electrolytic Oxidation ◽  
Pure Titanium ◽  
Commercially Pure Titanium ◽  
Corrosion Properties ◽  
Commercially Pure ◽  
Electrolytic Oxidation ◽  
Aluminum Oxide Layer ◽  
Plasma Electrolytic ◽  
Cp Ti ◽  
Peo Coatings

In this study, the surface of commercially pure titanium (Cp-Ti) was covered by a 21–95 µm-thick aluminum oxide layer using plasma electrolytic oxidation. Coating characterization revealed the formation of nodular and granular α- and γ-Al2O3 phases with minor amounts of TiAl2O5 and Na2Ti4O9 which yielded a maximum 49.0 GPa hardness and 50 N adhesive critical load. The corrosion resistance behavior in 3.5 wt.% NaCl solution of all plasma electrolytic oxidation (PEO) coatings was found to be two orders of magnitude higher compared to bare Ti substrate.

scholarly journals Effect of Pulse Current Mode on Microstructure, Composition and Corrosion Performance of the Coatings Produced by Plasma Electrolytic Oxidation on AZ31 Mg Alloy

Coatings ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 688 ◽  
Author(s):  
Maryam Rahmati ◽  
Keyvan Raeissi ◽  
Mohammad Reza Toroghinejad ◽  
Amin Hakimizad ◽  
Monica Santamaria
Keyword(s):  
Plasma Electrolytic Oxidation ◽  
Low Frequency ◽  
Current Mode ◽  
Mg Alloy ◽  
Corrosion Performance ◽  
Micro Cracks ◽  
Az31 Mg Alloy ◽  
Electrolytic Oxidation ◽  
Plasma Electrolytic ◽  
Peo Coatings

Plasma electrolytic oxidation (PEO) coatings were grown on AZ31 Mg alloy in a silicate-based electrolyte containing KF using unipolar and bipolar (usual and soft-sparking) waveforms. The coatings were dual-layered consisting of MgO, MgF2 and Mg2SiO4 phases. Surface morphology of the coatings was a net-like (scaffold) containing a micro-pores network, micro-cracks and granules of oxide compounds. Deep pores were observed in the coating produced by unipolar and usual bipolar waveforms. The soft-sparking eliminated the deep pores and produced the lowest porosity in the coatings. It was found that the corrosion performance of the coatings evaluated using EIS in 3.5 wt. % NaCl solution is mostly determined by the inner layer resistance, because of its higher compactness. After 4 days of immersion, the inner layer resistances were almost the same for all coatings. However, the coatings produced by unipolar and usual bipolar waveforms showed sharp decays in inner layer resistances after 1 week and even the barrier effect of outer layer was lost for the unipolar-produced coating after 3 weeks. The low-frequency inductive loops appeared after a 3-week immersion for all coatings indicated that the substrate was under local corrosion attack. However, both coatings produced by soft-sparking waveforms provided the highest corrosion performance.

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