Formation of unidirectional nanoporous structures in thickly anodized aluminum oxide layer
(1. Division of Materials Science and Engineering, Inha University, 253 Yonghyun-dong, Nam-gu,
Incheon, 402-751, Korea;
2. Samsung Electro-Mechanics Co., Ltd., 314, Maetan3-dong, Yeongtong-gu,
Suwon, Gyunggi-do, 443-743, Korea)
Incheon, 402-751, Korea;
2. Samsung Electro-Mechanics Co., Ltd., 314, Maetan3-dong, Yeongtong-gu,
Suwon, Gyunggi-do, 443-743, Korea)
Abstract: A series of anodic aluminum oxide(AAO) was grown on the commercially pure 1050 aluminum sheet by controlling electrolyte temperature (2−15 ℃) and anodizing time (0.5−6 h), using a fixed applied current density of 3 A/dm2 in diluted sulfuric acid electrolyte. A crack-free thick AAO with the thickness of 105−120 μm and containing unidirectional nano sized pores (average pore diameter of 5−7 nm) is successfully achieved in the specimens anodized for 2 h, irrespective of electrolyte temperature. When anodizing time reaches 6 h, very thick AAO with the thickness of 230−284 μm is grown, and average diameter of unidirectional pores is in the range of 6−24 nm. The higher values in both the AAO thickness and pore diameter are attained for the specimens anodized at higher temperatures of 10−15 ℃. A crack is observed to exist in the AAO after anodizing up to 4 h and more. A higher fraction (more than 9%) of the crack is shown in the specimens anodized at higher temperatures of 10−15 ℃ for 6 h and a considerable amount of giant cracks are contained.
Key words: aluminum; anodizing; unidirectional nanopore; anodic aluminum oxide