Sustainable micro-manufacturing of superhydrophobic surface on ultrafine-grained pure aluminum substrate combining micro-embossing and surface modification

A hybrid process combining hot micro-embossing process with subsequent surface modification was proposed to realize an economic, environmental-friendliness and reusable sustainable production of superhydrophobic surfaces on ultrafine-grained (UFG) pure aluminum substrate. Hot micro-embossing was executed using a silicon die at 523 K with the force of 4.5 kN, where an array of micro hexagonal pillar patterns was formed with feature side length ranging from 75 μm to 165 μm. The embossed micro array structures were clearly printed well, with a good geometric transitivity and no obvious disfigurement. After surface modification, the water contact angle of the embossed surface, following by immersed in boiling water with micro/nano hierarchical structures, reached ∼160° which increased by 142% compared with original UFG pure aluminum. Moreover, the mechanism of the obtained superhydrophobic surface with high adhesive force was analyzed, which would be attributed to the Cassie impregnating wetting regime. The research indicates that there is a potential application by using hot micro-embossing process in the mass and sustainable production of superhydrophobic surfaces with excellent adhesive property without pollution.