Hybrid pulse anodization for the fabrication of porous anodic alumina films from commercial purity (99%) aluminum at room temperature

Abstract

Most porous anodic alumina (PAA) or anodic aluminum oxide (AAO) films are fabricated using the potentiostatic method from high-purity (99.999%) aluminum films at a low temperature of approximately 0-10 degrees C to avoid dissolution effects at room temperature (RT). In this study, we have demonstrated the fabrication of PAA film from commercial purity (99%) aluminum at RT using a hybrid pulse technique which combines pulse reverse and pulse voltages for the two-step anodization. The reaction mechanism is investigated by the real-time monitoring of current. A possible mechanism of hybrid pulse anodization is proposed for the formation of pronounced nanoporous film at RT. The structure and morphology of the anodic films were greatly influenced by the duration of anodization and the type of voltage. The best result was obtained by first applying pulse reverse voltage and then pulse voltage. The first pulse reverse anodization step was used to form new small cells and pre-texture concave aluminum as a self-assembled mask while the second pulse anodization step was for the resulting PAA film. The diameter of the nanopores in the arrays could reach 30-60 nm.

Aluminum Templates of Different Sizes with Micro-, Nano- and Micro/Nano-Structures for Cell Culture

“…Varying the electrolyte and the electrolysis time yields alumina membranes with pore diameters up to several hundred nanometers, or as small as 5 nm. The hole density up to 1011 holes/cm [24][25][26][27] and film thickness from 10 to 100 µm can be obtained. The porous alumina template is by far the most widely used template because it has monodispersed characteristic, it can resist high temperatures, and has high strength.…”

Synthesis of Nanoporous Anodic Alumina by Anodic Oxidation of Low Purity Aluminum Substrates

“…For instance, Chung et al have observed that an oxide layer thickness and pore diameter increase with increasing concentration of the electrolyte and anodizing time [85]. At higher electrolyte concentrations, the conductivity of the whole cell increases that results in a higher current density and growth rate.…”

“…At higher electrolyte concentrations, the conductivity of the whole cell increases that results in a higher current density and growth rate. On the other hand, the AAO structures with denser pore distributions are formed when more concentrated electrolytes are used for anodizing [85].…”

“…However, the fabrication of highly ordered AAO films on the surface of AA1050 alloy by using this procedure is almost impossible without using the protection agent. An interesting approach to the fabrication of porous alumina layers on the surface of commercial purity Al (99 %) was proposed and extensively investigated by Chung et al [70,85,[93][94][95][96][97][98]. The authors have compared morphologies of the oxide layers formed by the conventional, potentiostatic method and two different pulse anodizations.…”

Electrochemically etched sharp aluminium probes with nanoporous aluminium oxide coatings: demonstration of addressed DNA delivery

“…The width of the positive pulse was selected based on the data from the kinetic curve of the electrical current density for the anodising process of planar surfaces in a standard (20 V DC, 0.3 M H 2 SO 4 ) electrolyte solution [20][21][22] (Fig. 5 inset).…”