부산대학교 도서관

Although several methods have been developed for fabricating three-dimensional (3D) porous metals, the preparation of 3D porous Al metal with micron-sized pores and a porosity exceeding 60% remains challenging because Al is inherently highly reactive with atmospheric oxygen and moisture. In this study, we investigate a novel method for fabricating 3D porous Al by selectively etching an Al–Zn alloy via Al passivation. Specifically, when an Al–Zn alloy with a microstructure consisting of Al and Zn phases was etched in concentrated nitric acid, the Al phase was passivated and the Zn phase was selectively dissolved. Consequently, a 3D porous structure composed of Al metal was formed. The pore size and porosity corresponded to the grain size and volume fraction of Zn grains in the Al–Zn alloy before etching, respectively. Therefore, porous Al with a large pore size was obtained through annealing by growing crystal grains in the Al–Zn alloy before etching. The pore size, and consequently the porosity, was further increased by etching porous Al with phosphoric acid. On combining annealing and etching, 3D porous Al was obtained with a mean pore size and porosity in the range of 0.4–2.4 μm and 60–80%, respectively. [ABSTRACT FROM AUTHOR]