Investigation of the Electrochemical Behavior of Coatings Formed by Plasma Electrolytic Oxidation in the Presence of an Electrolyte Containing Layered Double Hydroxide Nanostructures on AZ31 Magnesium Alloy

نوع: Type: Thesis

مقطع: Segment: masters

عنوان: Title: Investigation of the Electrochemical Behavior of Coatings Formed by Plasma Electrolytic Oxidation in the Presence of an Electrolyte Containing Layered Double Hydroxide Nanostructures on AZ31 Magnesium Alloy

ارائه دهنده: Provider: mehdi asadi

اساتید راهنما: Supervisors: omid imantalab-mazdak izadi

اساتید مشاور: Advisory Professors: arash fattah alhosseini

اساتید ممتحن یا داور: Examining professors or referees: mino karbasi-esmaeil damavandi

زمان و تاریخ ارائه: Time and date of presentation: 2025

مکان ارائه: Place of presentation: 71

چکیده: Abstract: In this study, the improvement of the corrosion behavior of AZ31 magnesium alloy using plasma electrolytic oxidation (PEO) coatings and layered double hydroxide (LDH) nanostructures at different concentrations (0.25, 0.5, 0.75, and 1 g/L) was investigated. PEO/LDH coatings were created by adding LDH nanostructures to the base electrolyte, and the effect of these nanostructures on the microstructure, surface properties, and corrosion behavior of the coatings was comprehensively studied. The results from scanning electron microscopy (SEM) showed that with increasing LDH concentration, the structure of the coatings became denser, and the porosity and pore size significantly decreased. The porosity and pore size were significantly reduced. The porosity in the sample containing 1 g/L of LDH reached 3.87%, and the average pore size was 13.42 µm. X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDAX) analyses confirmed the presence of magnesium oxide and magnesium silicate phases, as well as the uniform distribution of LDH nanostructures in the coatings. Corrosion tests, including electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization, demonstrated that coatings containing LDH exhibited higher electrical resistance and significantly reduced corrosion rates. The sample containing 1 g/L of LDH, with the highest resistance in both the inner and outer layers, provided the best protective performance against corrosion. This research indicates that the use of LDH nanostructures in PEO coatings can serve as an effective approach to enhancing the protective properties of magnesium alloys in corrosive environments, paving the way for the development of industrial applications of these alloys under corrosive conditions.

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