Fabrication of a super‐amphiphobic aluminium alloy surface via wire electrical discharge machining and chemical etching technology

Abstract

A simple method, involving twice electric machining by HS-WEDM and chemical etching, is used to fabricate super-amphiphobic (both super-hydrophobic and super-oleophobic) surfaces on aluminium alloy. The surface morphology of the samples was investigated using scanning electron microscopy and laser scanning confocal microscope. The evaluations of surface oleophobicity were carried out using the contact angles of ethylene glycol, diiodomethane and dodecane. Finally, the experimental result indicated that after the twice electric machining and chemical etching, the micro/nanometre-scale binary rough structure was presented on the sample surfaces, and the resulting sample surfaces produced in this method had super-hydrophobic and lipophilic properties (water contact angle of 155.74°). More importantly, after surface fluorination, the sample surfaces turned to super-amphiphobic surfaces and the biggest contact angles of water and oil were 156.24° and 157.34°, respectively. Therefore, it can be considered that the acquirement of the micro/nanometre-scale rough structures and the reduction of the surface energy are essential requirements to fabricate super-amphiphobic surfaces. The advantages of the present method over the other methods are that the used wire electrical discharge machining can machine most metals, and the processes of surface forming and microstructure fabrication were combined, which saves processing time greatly.