scholarly journals The Effect of Electrolytic Solution Composition on the Structure, Corrosion, and Wear Resistance of PEO Coatings on AZ31 Magnesium Alloy

Coatings ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 937
Author(s):  
Amirhossein Toulabifard ◽  
Maryam Rahmati ◽  
Keyvan Raeissi ◽  
Amin Hakimizad ◽  
Monica Santamaria
Keyword(s):  
Magnesium Alloy ◽  
Corrosion And Wear ◽  
Az31 Magnesium Alloy ◽  
Compact Structure ◽  
Uniform Distributions ◽  
Micro Cracks ◽  
Treated Sample ◽  
Relative Porosity ◽  
Plasma Electrolytic ◽  
Peo Coatings

Plasma electrolytic oxidation coatings were prepared in aluminate, phosphate, and silicate-based electrolytic solutions using a soft-sparking regime in a multi-frequency stepped process to compare the structure, corrosion, and wear characteristics of the obtained coatings on AZ31 magnesium alloy. The XRD results indicated that all coatings consist of MgO and MgF2, while specific products such as Mg2SiO4, MgSiO3, Mg2P2O7, and MgAl2O4 were also present in specimens based on the selected solution. Surface morphology of the obtained coatings was strongly affected by the electrolyte composition. Aluminate-containing coating showed volcano-like, nodular particles and craters distributed over the surface. Phosphate-containing coating presented a sintering-crater structure, with non-uniform distributions of micro-pores and micro-cracks. Silicate-containing coating exhibited a scaffold surface involving a network of numerous micro-pores and oxide granules. The aluminate-treated sample offered the highest corrosion resistance and the minimum wear rate (5 × 10−5 mm3 N−1 m−1), owing to its compact structure containing solely 1.75% relative porosity, which is the lowest value in comparison with other samples. The silicate-treated sample was degraded faster in long-term corrosion and wear tests due to its porous structure, and with more delay in the phosphate-containing coating due to its larger thickness (30 µm).

scholarly journals Effect of Applied Current Density of Plasma Electrolytic Oxidation Process on Corrosion Resistance of AZ31 Magnesium Alloy

2019 ◽  
Vol 21 (2) ◽  
pp. 32-36 ◽  
Author(s):  
Daniel Kajanek ◽  
Branislav Hadzima ◽  
Matej Brezina ◽  
Martina Jackova
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Current Density ◽  
Plasma Electrolytic Oxidation ◽  
Az31 Magnesium Alloy ◽  
Applied Current ◽  
Applied Current Density ◽  
Electrolytic Oxidation ◽  
Plasma Electrolytic ◽  
Peo Coatings

Impact of applied current density during the plasma electrolytic oxidation (PEO) process on corrosion resistance of AZ31 magnesium alloy was studied. The PEO coatings were prepared using four different current densities with values of 0.025 A/cm2, 0.05 A/cm2, 0.1 A/cm2 and 0.15 A/cm2 in electrolyte consisting of 10 g/l Na 3PO4.12H2O and 1 g/l KOH. Morphology and chemical composition of the coatings was examined using the scanning electron microscopy and EDS analysis respectively. Electrochemical characteristics of ground and coated samples were measured by means of electrochemical impedance spectroscopy (EIS) in 0.1M NaCl solution. Obtained data in form of Nyquist diagrams were analysed by equivalent circuit method. Results of experiments showed that value of applied current density had significant effect on protective performance of the PEO coatings prepared on AZ31 magnesium alloy surface.

Incorporation of Composite Zirconia-Silica Nanoparticles into PEO-Coatings on Magnesium Alloys

2018 ◽  
Vol 386 ◽  
pp. 321-325
Author(s):  
Igor M. Imshinetsky ◽  
Sergey V. Gnedenkov ◽  
Sergey L. Sinebryukhov ◽  
Dmitry V. Mashtalyar ◽  
Andrew V. Samokhin ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Silica Nanoparticles ◽  
Magnesium Alloys ◽  
Plasma Electrolytic Oxidation ◽  
Protective Coatings ◽  
Surface Layers ◽  
Electrolytic Oxidation ◽  
Plasma Electrolytic ◽  
Peo Coatings ◽  
The Way

The way of protective coatings formation on MA8 magnesium alloy by plasma electrolytic oxidation (PEO) in the electrolyte containing composite zirconia-silica nanoparticles has been developed. It is shown that the coatings, which contain nanoparticles, have a significant advantage in comparison with the surface layers obtained without their use.

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