Anodizing of Aluminum Coated with Silicon Oxide by a Sol-Gel Method

Abstract

Aluminum specimens were covered with SiO2 film by a sol-gel coating and then anodized galvanostatically in a neutral borate solution. Time variations in the anode potential during anodizing were monitored, and the structure and dielectric properties of the anodic oxide films were examined by transmission electron microscopy, Rutherford backscattering spectroscopy, and electrochemical impedance measurements. It was found that anodizing of aluminum coated with SiO2 films leads to the formation of anodic oxide films, which consist of an outer Al-Si composite oxide layer and an inner Al2O3 layer, at the interface between the SiO2 film and the metal substrate. The capacitance of anodic oxide films formed on specimens with a SiO2 coating was about 20% larger than without a SiO2 coating. In the film formation mechanism, the conversion of Al2O3 to Al-Si composite oxide at the interface between the inner and outer layers is discussed in terms of inward transport of Si-bearing anions across the outer layer. © 2001 The Electrochemical Society. All rights reserved.

Polypyrrole film on 55% Al–Zn-coated steel for corrosion prevention

“…This dielectric constant value is the value for the anodic oxide film of aluminium [47]. The thickness of the interfacial oxide layer ranged from 10 to 15 nm.…”

“…We believe that the parallel R it -C dl circuit at higher frequencies corresponds to the electrochemical response at the interface between the PPy layer and the solution, and R it and C dl were respectively an ionic transfer resistance at the interface and a double layer capacitance. The second parallel circuit in the lower frequencies may correspond to ionic transfer and diffusion elements in the PPy layer [47,48]. R i-PPy was assumed to be an ionic transfer resistance through the PPy layer, W is the Warburg diffusion impedance of mobile ions in the PPy layer, and C redox is the redox capacitance of the PPy layer [48,49].…”

Fabrication of a micro-porous Ti–Zr alloy by electroless reduction with a calcium reductant for electrolytic capacitor applications

“…= 9.8) and tantalum oxide (Ta 2 O 5 , ! = 27.6) [1][2][3][4][5][6][7]. Growth of the oxide film on titanium by anodizing, however, involves an amorphous-to-crystalline transition at low voltage, and this crystallization causes the formation of electron conductive pathways through the oxide film, enabling oxygen gas evolution on the crystalline oxides during anodizing.…”

Enhanced Capacitance of Composite Anodic ZrO2 Films Comprising High Permittivity Oxide Nanocrystals and Highly Resistive Amorphous Oxide Matrix

“…1,2 Because there is still a constant demand to improve the volume efficiency, many efforts have been made to enhance the capacitance of various capacitors, gate dielectrics, and so on. [3][4][5] The capacitance of capacitors is given by the following equation:…”