Hierarchical micro/nano structure surface fabricated by electrical discharge machining for anti-fouling application

Abstract

Surface that durably and anti-fouling are of interest for fundamental research and industrial application in the heat exchanger equipment. In the present study, hierarchical micro/nano structure (HMNS) is fabricated by electrical discharge machining (EDM) method. The morphology, metallographic and crystalline structures as well as corrosion resistance of the HMNS are characterized. The micro/nano structure improves the corrosion resistance and hydrophobic property of the surface. The HMNS, with the grain size dimension of 1.5–11 μm, shows an improved contact angle of 124.9° ± 5.4°. The co-effect of hydrophobic and corrosion resistance endows the HMNS with a superior anti-fouling property than that of polished surface. Fouling adhesion experiments shows that, after being immersed in CaCl2 + Na2CO3 solution for 72 h at 50 ℃, there are only a few fouling adhere on the HMNS and the adhered fouling is loose and easy to fall off. Moreover, after 50 times of semitransparent tape adhesion, the HMNS still in the hydrophobic status with slightly decreases (4.09%–9.38%) of contact angle, which indicates that the HMNS is durably and suitable for industrial application. There is an industrial prospect for fabricating anti-fouling heat transfer surface by a low cost and environmentally friendly one-step EDM process. Keywords: Electrical discharge machining, Hierarchical micro/nano structure, Hydrophobic, Anti-fouling, Corrosion resistance