One-step fabrication of the wear-resistant superhydrophobic structure on SiCp/Al composite surface by WEDM

Fabricating superhydrophobic structure on metal matrix can significantly improve its usability, such as anti-corrosion, self-cleaning, anti-icing, fluid drag reduction. However, the mechanical strength and wear resistance of the micro-nano structures on the common material (such as plastic/copper/aluminum/stainless steel) are not satisfactory. This paper aims to propose a high-efficiency and easy-operating method for fabricating wear-resistant superhydrophobic structure. Particle reinforced metal matrix composite (SiCp/Al) is chosen as workpiece material which has high specific strength, good wear resistance and low thermal expansion coefficient. A method of one-step fabricating multi-stage micro-nano structures for superhydrophobic structure on SiCp/Al composite surface using wire electrical discharge machining (WEDM) is presented. The primary structure and secondary structure are respectively semicircular groove texture and the surface microstructure from discharge machining. A set of cutting experiments are conducted to analyze the effect of the size of semicircular groove texture on the contact angle (CA) of workpiece surface. The multi-stage micro-nano structures on SiCp/Al composite surface is characterized by optical microscope, SEM, EDS. The experimental data shows that the maximum CA reaches 153.3° when the radius and center distance of semicircular groove texture are 400 μm and 700 μm, respectively. In addition, the superhydrophobic structure on SiCp/Al composite surface by WEDM exhibits excellent wear resistance. Eventually, the theoretical model of CA and the design criterion of semicircular groove texture for superhydrophobic structure are established. Specifically, the superhydrophobic structure can be obtained if the fraction of the solid-liquid area of the total projected surface area is lower than 0.084.