Effect of hydration on microstructure and property of anodized oxide film for aluminum electrolytic capacitor

Etched aluminum foil for aluminum electrolytic capacitor was first boiled in water for different time to form hydrous film on Al foil and then anodized in H 3 BO 4 solution at 530 V to form anodic oxide barrier film as insulating dielectric layer. The obtained films were characterized by field-emiss...

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Bibliographic Details
Published in:Journal of materials science. Materials in electronics 2018-10, Vol.29 (19), p.16166-16171
Main Authors: Ban, Chao-Lei, Wang, Fang-Ren, Chen, Jian-Hai, Liu, Zhen-Qi
Format: Article
Language:English
Subjects:
Aluminum
Aluminum oxide
Anodizing
Barriers
Capacitors
Characterization and Evaluation of Materials
Chemistry and Materials Science
Crystal structure
Crystallinity
Electrochemical analysis
Electrochemical impedance spectroscopy
Electron microscopes
Hydration
Materials Science
Metal foils
Microstructure
Morphology
Optical and Electronic Materials
Oxide coatings
Scanning electron microscopy
X-ray diffraction
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Summary:Etched aluminum foil for aluminum electrolytic capacitor was first boiled in water for different time to form hydrous film on Al foil and then anodized in H 3 BO 4 solution at 530 V to form anodic oxide barrier film as insulating dielectric layer. The obtained films were characterized by field-emission scanning electron microscopy, transmission electron microscope and X-ray diffraction for surface morphology, microstructure and crystallinity examination. Small-current charging, LCR meter and electrochemical impedance spectroscopy were exploited to measure the propertied of the anodized oxide film such as withstanding voltage ( U w ), specific resistance ( R ox ) and specific capacitance ( C s and C ox ) for its electrochemical performance. The results show that the hydrous film is pseudoboehmite (PB) with a dense inner layer and a fibrous outer layer. The crystallinity of the PB film increases with hydration time. During anodization, the PB film was transformed into anodic oxide (γ′-Al 2 O 3 ) barrier film. Prolonging hydration time promotes transformating PB into γ′-Al 2 O 3 and improves the crystallinity of the barrier film, leading to increase in C s and C ox and decrease in R ox and U w .
ISSN:0957-4522
1573-482X
DOI:10.1007/s10854-018-9705-9