Studies On Fabrication And Application Of Wettability-Controllable Aluminum Superhydrophobic Surfaces

Wettability is a very important property of superhydrophobic surfaces, wettability-controllable superhyrophobic surfaces can be applied in such technical areas as biochemical analysis and lab-on-chip devices.Electrochemical etching and stearic acid were exploited to fabricate aluminum alloy superhydrophobic surface. The influences of the main processing parameters (current density, etching time and concentration of electrolyte) on wettability of surperhydrophobic surfaces were investigated. The results show that with the current density increased, the contact angle firstly increased and then decreased; High current density would shorten the processing time, improving the efficiency of the preparation of surperhydrophobic surfaces; The electrolyte concentration has almost no effect on the contact angles and sliding angles. When the concentration of electrolyte was 0.1 molL"1, sliding angle reached the minimum value of 7.6°, indicating great dynamic superhydrophobic characteristics.Micro-milling machining process was proposed in the preparation of superhydrophobic surface with micro-sacle dot and array structures, the milled dots show high adhesion to water features. When the droplet fell off the dot, water stain was left in the dot, illustrating the micro-dot was hydrophilic. The influence of the diameter of the micro-crater on the adhesion performance of the droplet show that with the increase of the diameter, the adhesion of the droplet on the micro-crater increased linearly.By adjusting the temperature, wettability of stearic-acid-modified aluminum surperhydrophobic surface could be regulated. The control mechanism of temperature-driven wettability control was analyzed, and the reversibility of the wettability-controllable of the aluminum superhydrophobic was discussed. The results show that the contact angle of the sample decreased and the sliding angle increased with the increase of the temperature; The changes of the contact angle in the process of heating and cooling were reversible; With the increase of temperature alternating times, the sliding angle increased, indicating that the changes of temperature could lead to gradual transition from low-adhesion-state aluminum superhydrophobicity surface to high-adhesion-state-ones.