Anawati, Anawati and Hidayati, Efrina and Purwanto, Sugeng (2023) Effect of Cation Incorporation in the Plasma Electrolytic Oxide Layer Formed on AZ31 Magnesium Alloy. Applied Surface Science Advances, 17: 100444. ISSN 26665239
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The role of anion in the formation of oxide coating by plasma electrolytic oxidation (PEO) has been extensively studied. However, there was no clear evidence of the role of cation. This work is aimed to study the mechanism of sodium (Na) incorporation and its effect on the PEO coating formed on AZ31 magnesium (Mg) alloy in Na3PO4 electrolyte by post-mortem investigation. The study was performed on a porous and a dense coating developed at 1 and 5 min, respectively. Investigation using scanning electron microscope (SEM) and energy dispersive x-ray spectroscopy (EDS) revealed incorporation of Na as high as ∼10 at% in the coating as whiskers accumulated in the outer layer and as filler inside tunnels. Whiskers were composed of Mg3PO4 phase enclosed by Na-O compounds which was formed by chemical reactions of Na+ ions, oxygen (O2), and water (H2O) in the vicinity of plasma discharge. The polarization test demonstrated an order magnitude improvement of corrosion resistance provided by the porous coating while two orders of magnitude for the dense coating. The incorporation of Na compounds shifted the corrosion potential of the coated specimen ∼135 mV below the substrate. The EIS test indicated that Na compounds contributed to temporary passivation with exposure time.
| Item Type: | Article |
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| Additional Information: | The mechanism of sodium (Na) incorporation in the PEO coatings formed on AZ31 Mg alloy had been investigated in porous and dense coatings, respectively, having approximately a similar thickness of 49±2 μm. Based on the post-mortem investigation, the following conclusion has been made: • The Na compounds were incorporated as whiskers in the outer layer and as fillers inside tunnels. The thermochemical reaction between cation Na and oxygen (O2) or water (H2O) on the specimen surface presumably produced NaOH and Na2O compounds. The Na-O compounds enclosed the magnesium phosphate (Mg3PO4) fiber which contained traces amount of Al. • Whiskers were developed due to quenching of the molten oxide being discharged from the metal-oxide interface outward through tunnels, froze the substance into long fiber oxides called whiskers. • The Na compounds-containing electrolyte was sucked into the empty discharge tunnel by the capillary action and was trapped as fillers. • The Na incorporation did not contribute significantly to the mechanical hardness of the coatings. • The incorporation of Na compounds in the coating caused depression in the corrosion potential of the alloy. However, with increasing exposure time, the Na compounds help depress the corrosion activity temporarily. |
| Uncontrolled Keywords: | coating, magnesium, cation, whiskers, corrosion, plasma electrolytic oxidation |
| Subjects: | Bidang Keilmuan > Chemical Process Bidang Keilmuan > Chemical Materials Bidang Keilmuan > Chemistry Bidang Keilmuan > Corrosion Bidang Keilmuan > Electrochemical Bidang Keilmuan > Electrical Engineering Bidang Keilmuan > Electrochemical Technology Bidang Keilmuan > Electromechanical Technology Jurnal Bidang Keilmuan > Materials Engineering Bidang Keilmuan > Metallurgy Bidang Keilmuan > Oxidation Process Bidang Keilmuan > Teknik Elektro Bidang Keilmuan > Teknik Elektro Tenaga Listrik |
| Divisions: | Fakultas Ketenagalistrikan dan Energi Terbarukan > S1 Teknik Elektro |
| Depositing User: | Yudha Formanto |
| Date Deposited: | 17 Apr 2026 03:43 |
| Last Modified: | 17 Apr 2026 03:44 |
| URI: | https://repository.itpln.ac.id/id/eprint/6402 |
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