Pashchanka Mikhail
Department of Chemistry, Eduard-Zintl-Institute, Technical University of Darmstadt, Alarich-Weiss-Straße 12, 64287 Darmstadt, Germany.
Phys Chem Chem Phys. 2020 Jul 22;22(28):15867-15875. doi: 10.1039/d0cp01717e.
Herein, the one-step spontaneous formation of multiscale hierarchical honeycomb-like textures on anodized aluminium is reported for the first time. A self-organized array of unprecedentedly large sub-millimetre hemispherical pores was observed on the upper hierarchy level, while superimposed well-ordered hexagonal cells on the lower hierarchy level maintained their classically known nanoscale self-ordering periodicity (50-60 nm). The larger macroscopic cells (0.45-0.90 mm) show great morphological similarity to the conventional nanosized porous anodic structures, but arise on a purely metallic surface without any analytically detectable amount of deposited alumina. The observed cell size expansion (approximately by a factor of 104) during Al anodizing is colossal in comparison with the size variation ranges reported in the literature so far. It reveals a dramatic nonlinearity effect in a dynamic self-organizing system upon a moderate change of experimental parameters (specifically, this work focuses on the effect of anodizing temperature). Such multilevel self-organization in a single aluminium anodizing process sheds new light on the origin of self-ordered anodic structures and allows rethinking the whole range of opinions regarding their formation mechanism that have been proposed to date.
本文首次报道了在阳极氧化铝上一步自发形成多尺度分层蜂窝状纹理。在上层结构水平上观察到前所未有的大的亚毫米级半球形孔的自组织阵列，而在下层结构水平上叠加的有序六边形单元保持了其经典的纳米级自有序周期性（50 - 60纳米）。较大的宏观单元（0.45 - 0.90毫米）与传统的纳米级多孔阳极结构具有很大的形态相似性，但出现在纯金属表面，没有任何分析可检测到的沉积氧化铝量。与迄今为止文献报道的尺寸变化范围相比，在铝阳极氧化过程中观察到的单元尺寸扩展（约104倍）是巨大的。它揭示了在动态自组织系统中，实验参数适度变化时的显著非线性效应（具体而言，本工作重点关注阳极氧化温度的影响）。在单个铝阳极氧化过程中的这种多级自组织为自有序阳极结构的起源提供了新的见解，并促使人们重新思考迄今为止提出的关于其形成机制的所有观点。
