Analysis of the dependence of the structural parameters of membranes based on NOA and anode current on the parameters of the production process
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Date
2020-08
Authors
Batalova, M.S.
Alpysbayeva, B.E.
Korobova, N.E.
Journal Title
Journal ISSN
Volume Title
Publisher
The 8th International Conference on Nanomaterials and Advanced Energy Storage Systems; Nazarbayev University; National Laboratory Astana; Institute of Batteries
Abstract
Among the porous membranes, PAOA-based membranes, formed by the method of electrochemical
anodizing of aluminum foil, are of the greatest interest. Membranes obtained by electrochemical anodization
are highly ordered structures with parallel vertical pores [1]. The unique porous structure, the parameters
(diameter, length and distance between adjacent pores) of which can be varied during the synthesis process
allows the use of films of porous aluminum oxide as inorganic membranes, templating material for the synthesis
of nanowires or nanotubes with a controlled diameter and high geometric anisotropy, as well as 2D photonic
crystals and biosensors [2,3].
Aluminum foil (99.999%) with a thickness of 0.5 mm was used as the starting material for the synthesis
of films of porous aluminum oxide. Oxide layer formed on the foil surface was removed by electrochemical
polishing of aluminum in a mixture of 40g CrO3 + 210 ml H3PO4 (concentrated acid) + 45 ml H2O at a
temperature of 80°C. The membranes based on porous alumina were obtained by a two-stage anodizing process
in 0.4 M oxalic acid at a temperature of 4–19 ° C.
With an increase in the magnitude of the voltage, the thickness of the porous film, which grows in the
same time, increases; the growth rate of the film grows sublinearly. With increasing voltage value, the initial
value of the anode current also increases. The anode current in the anodization process gradually decreases,
which, as already noted, indicates the beginning of pore formation and further stabilization of the anode current
occurs when the pores grow deep into the oxide film. According to the data obtained on the dependence of the
anode current on the time of the anodization process, it can be concluded that the maximum current value at
room temperature is higher than at low temperature, and this can be traced for all voltage values.
Description
Keywords
NOA, aluminum foil, Research Subject Categories::TECHNOLOGY, PAOA-based membranes, electrochemical anodizing