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 (TiO 2 ). The main pore growth direction in Zn is along <0001>. The branching of side pores occurs along [1210] and [1210] 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.

Electrochemical Surface Structuring for Strong SMA Wire–Polymer Interface Adhesion

“…The surface structuring, which significantly improves the adhesion between metal ( e.g. , Al, Zn, Ti, and steel) surfaces and various polymers under mechanical load, can be done either chemically or electrochemically, as shown in the previous publications from our group. − Other research groups have already attempted to apply chemical etching to SMA surfaces to increase the interface adhesion. ,− Therefore, the SMA surface was immersed into an aqueous acidic solution containing HCl, HNO 3 , H 2 SO 4 , and/or HF, while the treatment time varied from minutes to several hours. Generally, an improvement of interface adhesion was observed, attributed to the increased surface roughness of the SMA wire .…”

How to Obtain High Load-Bearing Al-Cu Joints by Nanoscale Sculpturing

“…Recently, it has been shown that nanoscale sculpturing of pure metals and metal alloys can generate a metal surface offering a multitude of undercut surface structures per mm 2 allowing for an efficient mechanical interlocking with another material. [54][55][56][57][58] For the work presented here, this second material is Cu. The decisive point for such an Al-Cu joint is that the nanoscale sculptured Al surface structures must be enclosed by Cu to mechanically anchor the Cu layer, and thus, forming a high strength joint even under high mechanical loads without an intermetallic layer in between the Cu and Al joining partners.…”