Nanoporous alumina formed by self-organized two-step anodization of Ni₃Al intermetallic alloy in citric acid

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• 作者：Wojciech J. Stę ; pniowski ; ^{wstepniowski@wat.edu.pl} ; Grzegorz Cieś ; lak ; Mał ; gorzata Norek ; Krzysztof Karczewski ; Marta Michalska-Domań ; ska ; Dariusz Zasada ; Wojciech Polkowski ; Paweł ; Jó ; ź ; wik ; Zbigniew Bojar
• 关键词：Nanopores ; Anodization ; Self-organization ; Anodic oxide ; Electrochemical impedance spectroscopy
• 刊名：Applied Surface Science
• 出版年：2013
• 出版时间：1 January, 2013
• 年：2013
• 卷：264
• 期：Complete
• 页码：605-610
• 全文大小：1084 K

文摘

Formation of the nanoporous alumina on the surface of Ni₃Al intermetallic alloy has been studied in details and compared with anodization of aluminum. Successful self-organized anodization of this alloy was performed in 0.3 M citric acid at voltages ranging from 2.0 to 12.0 V using a typical two-electrode cell. Current density records revealed different mechanism of the porous oxide growth when compared to the mechanism pertinent for the anodization of aluminum. Electrochemical impedance spectroscopy experiments confirmed the differences in anodic oxide growth. Surface and cross-sections of the Ni₃Al intermetallic alloy with anodic oxide were observed with field-emission scanning electron microscope and characterized with appropriate software. Nanoporous oxide growth rate was estimated from cross-sectional FE-SEM images. The lowest growth rate of 0.14 ¦Ìm/h was found for the anodization at 0 ¡ãC and 2.0 V. The highest one - 2.29 ¦Ìm/h - was noticed for 10.0 V and 30 ¡ãC. Pore diameter was ranging from 18.9 nm (2.0 V, 0 ¡ãC) to 32.0 nm (12.0 V, 0 ¡ãC). Interpore distance of the nanoporous alumina was ranging from 56.6 nm (2.0 V, 0 ¡ãC) to 177.9 nm (12.0 V, 30 ¡ãC). Pore density (number of pore occupying given area) was decreasing with anodizing voltage increase from 394.5 pores/¦Ìm² (2.0 V, 0 ¡ãC) to 94.9 pores/¦Ìm² (12.0 V, 0 ¡ãC). All the geometrical features of the anodic alumina formed by two-step self-organized anodization of Ni₃Al intermetallic alloy are depending on the operating conditions.