Characterization of porous anodic alumina with AC-incorporated silver

Autor: Rositsa Мancheva, D. D. Kiradzhiyska, S. Kozhukharov, Ch. Girginov
Rok vydání: 2018
Předmět:
Zdroj: Electrochimica Acta. 292:614-627
ISSN: 0013-4686
DOI: 10.1016/j.electacta.2018.08.152
Popis: The present research is dedicated to the description of the effects of AC electrochemical incorporation of silver on the compositional, morphological and structural characteristics of the obtained modified anodic aluminum oxide (AAO) layers. The AC electrochemical Ag-incorporation was performed on preliminary galvanostatically anodized technically pure (AA1050) aluminum alloy for different durations (up to 900 s). The obtained Al-O-Ag combined layers were submitted to systematic characterizations in order to determine the incorporation efficiency and the respective process mechanism. The performed analyses comprised subsequent determination of: (i) chemical composition, (ii) surface topology and roughness, (iii) layer thickness and uniformity, and (iv) electrochemical behavior in 3.5% NaCl model corrosive medium. The Ag content and the respective incorporation efficiency were estimated by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). The topological and morphological modifications of the films were determined by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM), respectively. The morphological characterizations were completed by surface and cross-sectional Energy Dispersion X-ray (EDX) analyses thus determining the film thicknesses and elements distribution. All characterizations using these analytical methods were finalized by studying the performance of these films in a model corrosive medium by Electrochemical Impedance Spectroscopy (EIS) and Linear Sweep Voltammetry (LSV). The further comprehensive data analysis of the obtained results has enabled to create a conceptual model for the description of the correlations between the Ag-incorporation duration and the resulting compositional, topological and structural features, and the resulting film properties and performance. The AC electrochemical Ag-incorporation has a relatively low efficiency and proceeds with gradual silver deposition in the bottoms of the pores and its further accumulation in an upward direction. The cause for the observed low efficiency is related to the simultaneous occurrence of AAO layer growth and dissolution during the AC polarization, which result in topological and roughness variations, as well.
Databáze: OpenAIRE
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