Aluminum Anodization in Deionized Water as Electrolyte

Aleksey D Lisenkov,Mário G S Ferreira,Sergey K Poznyak,Mikhail L Zheludkevich

doi:10.1149/2.0881607jes

Aleksey D Lisenkov, Mário G S Ferreira + Show 2 more

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https://doi.org/10.1149/2.0881607jes

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Abstract

Thin oxide films were prepared electrochemically on the aluminum surface using the high-voltage discharge and potentiostatic methods in deionized water as an electrolyte. The growth of continuous films occurred only at potentials lower than the breakdown potential. The films obtained by the discharge method are more uniform and can grow to a higher thickness in comparison to those formed by the potentiostatic mode, as demonstrated by electrochemical impedance spectroscopy (EIS), transmission electron microscopy (TEM), and scanning Kelvin probe force microscopy (SKPFM). The data herein obtained can be used as a reference to understand better the properties of the films produced in conventional electrolytes where apart from water other species are present.

Highlights

In all electrolytes used for anodization, different ionic species are added to increase the conductivity of solution and the foreign atoms are trapped into the growing oxide.[8]
Impurity-free oxide on the metal surface can be prepared by other methods, such as oxidation in oxygen atmosphere at high temperature[1] or in boiling water,[10] but the properties of the obtained films will be different of those prepared by electrochemical oxidation
The formation of oxide films on the aluminum surface in deionized water was demonstrated in the current work by several methods: transmission electron microscopies (TEM), electrochemical impedance spectroscopy (EIS), scanning Kelvin probe force microscopy (SKPFM)

Summary

Introduction

Anodizing treatment is widely used on aluminum and its alloys in industrial practice to enhance surface performance (corrosion resistance, hardness and wear resistance) and to modify physical and chemical properties of the metal surface.[1,2] Anodization is a convenient and important method of oxide film formation owing to low cost, flexibility and easiness.[3,4,5,6,7] There are several anodization processes that are currently used: conventional anodic oxidation (potentiostatic or galvanostatic) and plasma electrolytic oxidation (PEO).[3,4,5,7] The conventional anodization is well studied and allows growing oxide films of controlled thickness and quality.[5,7] The films can be partially hydrated.[5]. Impurity-free oxide on the metal surface can be prepared by other methods, such as oxidation in oxygen atmosphere at high temperature[1] or in boiling water,[10] but the properties of the obtained films will be different of those prepared by electrochemical oxidation. This motivates the present work where only deionized water was used as an electrolyte.

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