Fog-capturing And Droplet Motion On A Conical Copper Wire With Gradient Wettability Surface

The main research works are summarized as follows:First,five kinds of wetting surfacesincluding uniform superhydrophobic surface with contact angle of 155.8°,gradient surfaces with contact angle ranged from 155.8° to 95.1°,124.9°-40.7°,78.6°-4.6°,and uniform superhydrophilic surface with contact angle of 4.6° were prepared on the conical copper wires withapex angle of 4° and length of 17 mm via a facile alkali assistant oxidation technique,respectively.The influence of different wetting surfaces on droplet motion velocity and fog-capturing rate,and the influence of droplet volume and apex angle on droplet motion velocity were discussed.It was found that the fog-capturing rate was much larger on the more hydrophobic surface,the droplet motion velocity was much larger on the more hydrophilic surface,and the droplet motion velocity is directly proportional to the droplet volume and apex angle.Scanning Electron Microscopy(SEM)and X-ray Diffraction(XRD)were employed to analyze the wettability,morphologies and crystal structure of the Cu(OH)2nanoribbon arrays on copper substrate.The stable performance of gradient wettability surface was tested.Secondly,three kinds of wetting surfaces with contact angle ranged from 156° to 95.6°,125.3°-41.2° and 78.6°-4.6°were prepared on the conical copper wires with apex angle of 4° and length of 17 mm via electrochemical deposition technique,respectively.The influence of different wetting surfaces on droplet motion velocity and fog-capturing rate were discussed.It was found that the fog-capturing rate is much larger on the gradient wettability surface prepared by alkali assistant oxidation technique;the droplet motion velocity is much larger on the gradient wettability surface prepared by electrochemical deposition technique.In the fog collection experiment,it was found that the fog-capturing rate was the dominate factor for fog collection when the fog flow velocity is low;the droplet motion velocity was the dominate factor of the fog collection when the fog flow is high.Scanning Electron Microscopy(SEM)and X-ray Diffraction(XRD)were adopted to explain the formation mechanism of gradient wettability surface.The stable performance of gradient wettability surface was tested.Finally,Multistage copper cones were made by gradient electrochemical corrosion and impressed isolation protection methods.Gradient wettability surface with contact angle ranged from 78.6°to 21.3°was prepared on the conical copper wires with apex angle of 4° and length of 21 mm via replacement technique.The droplet motion length with volume of 2μL on the one or three segment(s)copper cone was compared,and the influence of droplet volume on droplet movement was discussed.It was found that the droplet motion length with volume of 2μLon the three segments copper cone was l83.6% larger than that of the one segment copper cone.The larger the volume of droplet,the easier it was to move long length on the multistage copper cones.Scanning Electron Microscopy(SEM)and X-ray Diffraction(XRD)were adopted to explain the formation mechanism of gradient wettability surface.The stable performance of gradient wettability surface was tested.