The super-hydrophobic copper surface was obtained by using a nanosecond pulsed laser. Different micro-and nano-structures were fabricated by changing the laser scanning interval and scanning speed, before heating in an electric heater at 150 • C for two hours to explore the effect of laser parameters and heat treatment on the wettability of the copper surface. It was found that the laser-treated copper surface is super-hydrophilic, and then, after the heat treatment, the surface switches to hydrophobic or even super-hydrophobic. The best super-hydrophobic surface's apparent contact angle (APCA) was 155.6 • , and the water sliding angle (WSA) was 4 • . Super-hydrophobic copper is corrosion-resistant, self-cleaning, and dust-proof, and can be widely used in various mechanical devices.In order to find the best super-hydrophobic metal surface, we should know the reasons behind certain materials being super-hydrophobic.A dense column micro-or nano-structure is the key factor causing a super-hydrophobic surface. Thus, when we look for a super-hydrophobic surface, micro-and nano-scale dense column structures, such as the microstructures of lotus leaves, bird feathers, and butterfly wings, are considered. Although there are many ways to fabricate the hybrid micro/nano-structure on the material surface, such as chemical vapor deposition, chemical etching, nano-imprint lithography, electrode position, etc., there are various problems in their application [8][9][10][11][12][13][14][15][16][17]. For example, the size of the micro/nano-structure formed by the chemical etching method is very sensitive to external conditions such as temperature and concentration of chemical solution. In addition, etching reagents are mostly corrosive reagents with safety and environmental issues. Unlike the above methods, lasers can fabricate and precisely control the size of micro/nano-structures [18][19][20][21][22][23]. Therefore, laser processing can be used to quickly obtain micro/nano-structures. Recent studies found that the surfaces of metal oxides and nanostructures formed by laser ablation are initially hydrophilic or even super-hydrophilic; however, over time, they become hydrophobic, and sometimes even super-hydrophobic in air after two weeks to two months [24]. Several mechanisms were proposed to explain this phenomenon. Chang et al. proposed that the deoxidation of copper oxide could effectively promote the development from a hydrophilic to a super-hydrophobic surface [25,26]. Boinovich et al. believed that metal oxides adsorbed organics in the air, resulting in the transition from a super-hydrophilic to super-hydrophobic surface [27,28]. It can be seen that, although most researchers extensively studied this topic, there is obvious controversy regarding the mechanism of the wettability transition behavior.In this paper, a rapid method of fabricating a super-hydrophobic surface on a copper plate was studied. Micro/nano-structures were fabricated on copper surfaces by laser ablation, which then became super-hydrophobic after heat t...
