Patterned Superhydrophobic-philic Surface Fabricated By Picosecond Laser Texturing On Metal Surface

Due to the exhausting of land resources,more and more resources developing were forced to turn to the ocean.Many bionic artificial surfaces with complex functions have been continuously applied in marine engineering equipment and high-tech ships.Bionic superhydrophobic/superhydrophilic surface provide various functional applications with their special wettability in underwater environments.In this paper,picosecond laser scanning galvo-scanner system combined with a coating method were used to design and fabricated graphical extreme wettability surface,and application scheme of super-hydrophobic/super-hydrophilic and patterned extreme wettability surface were discussed on marine engineering equipment,in terms of biological adhesion resistance,buoyancy enhancement and resistance reduction.In the thesis,the fabrication and applications of extreme wettability metal surfaces prepared by picosecond laser etching technology were studied as following:?1?The influence of surface with rough structure ablated by picosecond laser etching stainless steel with different micro-morphologies was studied.and the relationship between laser fluence and etching depth,width or pit diameter were investigated in detail.On this basis,the influencing mechanism of laser parameters to surface wettability is summarized.?2?Self assembling of shape tunable air bubbles was achieved on the designated surface with hybrid SH/SHL patterns that fabricated by the second selective laser texturing of the prepared SH plate.The drag reduction test was done to investigate the surface with different shapes of adhered bubbles with a self-designed test system.The bubble adhered to the bottom surface increases the load capacity of the substrate,and an outstanding weight loading capacity which is 1.34 times of self-weight on a 20 cm² aluminum alloy plate was gained with strip-shaped air bubbles adhered to the sample bottom surface.The results of sailing test indicated that this sample increase 13%sailing distance than that of the untreated bare sample.By controlling the adhesion and detachment of the bubble,the vessel can be accelerated or deceleratedy,and is an potentially application in marine navigation.?3?The water drop impact behaviors on SH/SHL surface were experimentally investigated with Weber number.As the splashing occurred when droplet impacting at high Weber number,and the splashing inhibition property of patterned hybrid superhydrophobic/superhydrophilic surface was discussed.When the superhydrophobic area is circular with the diameter ratio D_p/D₀?D_p is the diameter of pattern inscribed circle,D₀ is the diameter of water droplet?is less than 1.0 and the Weber number is less than 600,the splashing can be totally suppressed.This hydrid wetted surface has great application in shipbuilding industry,droplet deposition,inkjet printing and precision coating spraying.?4?The anti-bioadhesion property of superhydrophobic surfaces with micro-groove and micro-pit structure were studied in seawater,and the influence mechanism of micro-nano structure to this property was also studied..The results of five weeks seawater immersion test showed that the specimens with SHS demonstrate significant anti-biofouling effect as compared with the bare stainless steel plate,the SHSs with micro-pit array and micro-groove array lead to the Avg.MAARs decrease from 92%to 57%and 43%,respectively.The laser induced micro-nano structures of the microgroove array were much more abundant than that of the micro-pit array,which led to the better anti-biofouling performance.