Self-Organized Growth of Crystallographic Macropores in Multicrystalline Zn by Nanoscale Sculpturing

Abstract

The self-organized formation of crystallographically oriented macropores in multicrystalline Zn is presented in the present paper. These pores are obtained by pulsed-potential electrochemical etching in an aqueous KCl electrolyte. They exhibit the typical characteristics of crystallographically-oriented pores like growth along certain crystallographic directions, formation of pore domains, branching of pores, and intersections of pores, as observed for e.g. III-V semiconductors such as InP. The pore walls of the pores in Zn are entirely composed of metallic Zn unlike the amorphous metal oxide ones observed in other metals like Al (AAO) or Ti (TiO2). The main pore growth direction in Zn is along <0001>. The branching of side pores occurs along [] and [] in 90° angles from the root pore forming a pore geometry reminding remotely on a monkey puzzle tree. Because of their crystallographic nature of the pores they grow under various angles into the multicrystalline Zn surface depending on the underlying crystal orientation. Like this they form a perfectly suitable structure for mechanical interlocking with polymers. When filled with polymer, the root pores together with the branched side pores act as ideal hooks anchoring the polymer in Zn solving the well-known problem of poor adhesion of polymers and paint on Zn surfaces.