Self-Ordering of Porous Anodic Alumina Fabricated by Anodizing in Chromic Acid at High Temperature
Self-Ordering of Porous Anodic Alumina Fabricated by Anodizing in Chromic Acid at High Temperature
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DOI：
10.1149/1945-7111/ac2101
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发表时间：
2021-09
影响因子：
3.9
通讯作者：
T. Kikuchi;Motoki Yamashita;M. Iwai;R. Suzuki
中科院分区：
文献类型：
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作者：
T. Kikuchi;Motoki Yamashita;M. Iwai;R. Suzuki
在铬酸中对铝进行阳极氧化是一种非常有用的表面处理工艺，可用于腐蚀防护和纳米级多孔结构制造，而多孔阳极氧化铝（PAA）在铬酸中的自有序性迄今为止尚未被发现。在此，我们通过高温铬酸阳极氧化提供了一种自序 PAA 薄膜，该薄膜具有许多亚 100 纳米级的特征凸块。在传统低温（例如 293 K）下，在 0.3 M 铬酸溶液中对高纯度 Al 板进行阳极氧化，会形成无序的 PAA 膜，而在 348 K 高温下进行阳极氧化，会导致孔结构的自有序行为。初始阶段生长的PAA薄膜具有最高的规则性，并且由于阳极氧化过程中孔的分支，它随着阳极氧化时间的延长而降低。通过在 348 K、120 V 条件下在铬酸中进行短期两步阳极氧化，可以制备出孔间距约为 340 nm 的高度有序 PAA 薄膜。有序 PAA 薄膜具有由六边形排列的 100 nm 级孔和孔壁上亚 100 nm 级无序凸块组成的特征纳米结构，且不含任何电解质铬酸盐阴离子。
Anodizing Al in chromic acid is a very useful surface finishing process for corrosion protection and nanoscale porous structure fabrication, whereas the self-ordering of porous anodic alumina (PAA) in chromic acid has never been found to date. Herein, we provide a self-ordered PAA film possessing numerous sub100-nm-scale characteristic bumps through anodizing in chromic acid at high temperature. Anodizing of high purity Al plates in a 0.3 M chromic acid solution at conventional low temperatures, such as 293 K, leads to the formation of a disordered PAA film, whereas anodizing at a high temperature of 348 K causes the self-ordering behavior of the pore structure. The PAA film grown in the initial stage possessed the highest regularity, and it decreased with anodizing time due to pore branching during anodizing. A highly ordered PAA film measuring approximately 340 nm in interpore distance can be fabricated by short-term, two-step anodizing in chromic acid at 348 K and 120 V. The ordered PAA film possesses a characteristic nanostructure consisting of hexagonally arranged 100-nm-scale pores and sub100-nm-scale disordered bumps on their pore walls without any electrolyte chromate anion.