Cathodic Electrodeposition of Cerium-Based Conversion Coatings Using Deep Eutectic Solvents Formulations for Corrosion Protection of AA7075 Aluminum Alloys
The paper presents a new approach towards forming Ce-based nanostructures using deep eutectic solvents (DESs) as new green solvents and large-scale media for the chemical and electrochemical synthesis of advanced functional surfaces and nanomaterials. Some experimental results regarding the cathodic...
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| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2024-12-01
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| Series: | Metals |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2075-4701/15/1/20 |
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| Summary: | The paper presents a new approach towards forming Ce-based nanostructures using deep eutectic solvents (DESs) as new green solvents and large-scale media for the chemical and electrochemical synthesis of advanced functional surfaces and nanomaterials. Some experimental results regarding the cathodic electrodeposition of cerium-based conversion coatings onto AA7075 aluminum alloys involving different DES-based formulations are discussed. Electrolytes containing Ce(NO<sub>3</sub>)<sub>3</sub>·6H<sub>2</sub>O dissolved in choline chloride-glycerine and choline chloride-urea (1:2 molar ratio) eutectic mixtures with additions of H<sub>2</sub>O<sub>2</sub> have been proposed and investigated. The influence of the operating parameters, including the applied current density, process duration and temperature on the quality of the formed Ce-containing conversion layers was studied. Adherent and uniform Ce-based conversion layers containing 0.3–5 wt.%. Ce have been obtained onto Al alloy substrates. Higher values of the applied current density and longer process durations led to higher Ce content when a choline chloride-urea eutectic mixture was used. Several accelerated corrosion tests were performed to evaluate the corrosion performance, respectively: (i) continuous immersion in 0.5 M NaCl for 720 h with intermediary visual examinations, recording of (ii) potentiodynamic polarization curves and of (iii) impedance spectra at open circuit potential in 0.5 M NaCl, as well as (iv) salt mist test for 240 h. The influence of an additional post-treatment step consisting in the electrochemical deposition of a hydrophobic Ce-based layer involving ethanolic solutions of stearic acid and cerium nitrate is also considered. Different corrosion performances are discussed, taking into account the used DES-based systems and electrodeposition parameters. |
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| ISSN: | 2075-4701 |