Structural engineering of nanoporous anodic aluminium oxide by pulse anodization of aluminium (original) (raw)
Related papers
Controlling the anodizing conditions in preparation of an nanoporous anodic aluminium oxide template
Materials Science-Poland, 2014
Porous anodic aluminium oxide (AAO) template is commonly used in the synthesis of one-dimensional nanostructures, such as nanowires and nanorods, due to its simple fabrication process. Controlling the anodizing conditions is important because of their direct influence on the size of AAO template pores; it affects the size of nanostructures that are fabricated in AAO template. In present study, several alumina templates were fabricated by a two-step electrochemical anodization in different conditions, such as the time of first process, its voltage, and electrolyte concentration. The effect of these factors on pore diameters of AAO templates was investigated using scanning electron microscopy (SEM).
Progress in Nano-Engineered Anodic Aluminum Oxide Membrane Development
Materials, 2011
The anodization of aluminum is an electro-chemical process that changes the surface chemistry of the metal, via oxidation, to produce an anodic oxide layer. During this process a self organized, highly ordered array of cylindrical shaped pores can be produced with controllable pore diameters, periodicity and density distribution. This enables anodic aluminum oxide (AAO) membranes to be used as templates in a variety of nanotechnology applications without the need for expensive lithographical techniques. This review article is an overview of the current state of research on AAO membranes and the various applications of nanotechnology that use them in the manufacture of nano-materials and devices or incorporate them into specific applications such as biological/chemical sensors, nano-electronic devices, filter membranes and medical scaffolds for tissue engineering.
Materials Chemistry and Physics, 2012
In aluminum anodization process the spontaneous current oscillation in certain electrolytes and anodization voltages can occur. The behavior of current in this process is called spontaneous oscillatory current otherwise we call the current behavior as non-oscillatory. The current difference between the spontaneous oscillatory and non-oscillatory conditions is appreciable (more than 50 mA/cm 2) whereas to switch from spontaneous oscillatory to non-oscillatory behavior we only need to change the anodization voltage less than 3 V. The pore structure of porous anodic alumina film can be modulated by this oscillatory behavior. This effect occurs due to the variation of the anodization current which causes the variation of pore diameter along the pores. But by this procedure it is hard to control the structure of the pore as it is required, because the modulated structure mainly depends on the spontaneous current oscillation. In this article, it is shown that this spontaneous oscillatory behavior can be switched to nonoscillatory condition by changing the anodization voltage. Therefore by switching the anodization voltage between the spontaneous oscillatory and non-oscillatory behaviors, in any time interval, the pore structure of nanopore alumina can be engineered.
Formation of nanoscale pore arrays during anodization of aluminum
Europhysics Letters (EPL), 2005
A theory of the spontaneous formation of spatially regular hexagonal arrays of nanopores in aluminum oxide film growing during aluminum anodization is presented. Linear stability analysis shows that, in certain ranges of the applied voltage and electrolyte pH, the oxide film is unstable with respect to perturbations with a well-defined wavelength. The instability is caused by a positive feedback between the oxidation-dissolution rates and variations of electric field caused by perturbations of the metal-oxide and oxide-electrolyte interfaces. The competition between this instability and the stabilizing effects of the Laplace pressure and elastic stress provides the wavelength selection mechanism. The hexagonal ordering of pores results from the resonant quadratic nonlinear interaction of unstable modes.
2012
Anodizing is an electrochemical process that converts the metal surface into a decorative, durable, corrosion-resistant, anodic oxide finish. Aluminum is ideally suited to anodizing, although other nonferrous metals, such as magnesium and titanium, also can be anodized. The anodic oxide structure originates from the aluminum substrate and is composed entirely of aluminum oxide. This aluminum oxide is not applied to the surface like paint or plating, but is fully integrated with the underlying aluminum substrate, so cannot chip or peel. It has a highly ordered, porous structure that allows for secondary processes such as coloring and sealing. In this experimental paper, we focus on a reliable method for fabricating nanoporous alumina with high regularity. Starting from study of nanostructure materials synthesize methods. After that, porous alumina fabricate in the laboratory by anodization of aluminum oxide. Hard anodization processes are employed to fabricate the nanoporous alumina ...
The Kinetics and Mechanism of Long-Range Pore Ordering in Anodic Films on Aluminum
The Journal of Physical Chemistry C, 2011
Anodic aluminum oxide (AAO) is a typical self-ordered mesoporous material. Since the pioneering work 1 of Masuda and Fukuda in 1995, which showed the opportunity of the formation of large scale ordered structures, AAO has been intensively used as a platform for creating various nanostructured functional devices. 2À5 Detailed understanding of the self-organization process is crucial for the further improvement of their functional properties. For example, long-range ordering is prerequisite for utilization of AAO as high-permeability porous membranes and many template issues.
Porous and mesh alumina formed by anodization of high purity aluminum films at low anodizing voltage
Thin Solid Films, 2014
Electrochemical oxidation of high-purity aluminum (Al) films under low anodizing voltages (1-10) V has been conducted to obtain anodic aluminum oxide (AAO) with ultra-small pore size and inter-pore distance. Different structures of AAO have been obtained e.g. nanoporous and mesh structures. Highly regular pore arrays with small pore size and inter-pore distance have been formed in oxalic or sulfuric acids at different temperatures (22-50°C). It is found that the pore diameter, inter-pore distance and the barrier layer thickness are independent of the anodizing parameters, which is very different from the rules of general AAO fabrication. The brand formation mechanism has been revealed by the scanning electron microscope study. Regular nanopores are formed under 10 V at the beginning of the anodization and then serve as a template layer dominating the formation of ultra-small nanopores. Anodization that is performed at voltages less than 5 V leads to mesh structured alumina. In addition, we have introduced a simple one-pot synthesis method to develop thin walls of oxide containing lithium (Li) ions that could be used for battery application based on anodization of Al films in a supersaturated mixture of lithium phosphate and phosphoric acid as matrix for Li-composite electrolyte.
On the Growth of Highly Ordered Pores in Anodized Aluminum Oxide
Chemistry of Materials, 1998
It is now established that hexagonally ordered domain structures can be formed in anodic alumina films by repeated anodization and stripping of the porous oxide. We find that the domain size is a linear function of time and increases with temperature. The pore density is initially high but decreases with anodizing time, as dominant pores deepen. Very small pores exist in native oxide in air or nucleate after electropolishing. Pore growth may start when the electric field increases at the pore bottoms, and acid dissolves the oxide locally.