Fabrication And Properties Of Superhydrophobic Surfaces On Metal Substrates By Nanosecond Laser

Superhydrophobic surfaces exist widely in natural life,such as lotus leaf surface,rice leaf surface,spider surface,water strider legs and so on.These superhydrophobic surfaces often bring some peculiar functions to these organisms,so the research on superhydrophobic surfaces has increased rapidly in recent years.Superhydrophobic surfaces requires two conditions,namely,the construction of surface micro-nanostructures and the reduction of surface energy.Among them,there are many methods to construct micro-nanostructures,including chemical deposition,chemical etching,electrochemical etching,spraying,lithography,laser etching and so on.In this paper,superhydrophobic surface is prepared by laser etching.Compared with other methods,laser etching has the advantages of simple operation,fast processing speed,easy control of processing parameters,high repeatability and suitable for mass processing.But at present,most of the superhydrophobic surfaces are fabricated by expensive femtosecond and picosecond lasers,and the cost of fabrication and maintenance is relatively high.In this paper,optical fiber laser marking machine is used to process metal surface.The optical maser use nanosecond laser with a wavelength of 1064 nm.Compared with picosecond laser and femtosecond laser,which are commonly used to prepare superhydrophobic surface,nanosecond laser has longer single pulse time and lower cost.Nanosecond lasers are also cheaper than femtosecond and picosecond lasers in cost,easy to manufacture,low maintenance cost and high repetition rate.The surface microstructures after nanosecond laser processing are related to laser parameters.This paper mainly discusses the influence of laser scanning speed,laser frequency and laser power on the surface structure of machined metal.The metal surface processed by nanosecond laser shows orderly and regular alignment of protrusions and pits.Increasing the scanning rate will reduce the peak value of the surface;Increasing the laser frequency will make the arrangement of protrusions and pits on the surface change into wave structure;Increasing the laser power will obviously increase the peak value of the material surface.The superhydrophobic properties of various metals processed with different laser parameters are discussed.Different metals have different degree of difficulty in laser processing because of their different thermodynamic parameters and laser absorption coefficient.In this paper,the optimum parameters of laser processing for pure aluminium,stainless steel,titanium alloy and pure copper are designed and experimented by means of orthogonal experimental grouping.Based on the analysis of experimental data,the optimum parameters of laser processing for four kinds of experimental metals are summarized,and the surface morphology of each metal after laser processing is analyzed.In addition,the self-cleaning,anti-corrosion,anti-friction and anti-icing of superhydrophobic surface fabricated by laser processing were also studied.Compared with ordinary aluminum surface,superhydrophobic aluminum surface processed by laser can remove surface dust by rolling droplets,which has good self-cleaning performance.Superhydrophobic surface has good corrosion resistance,surface corrosion inhibition rate as high as 99.8%.Superhydrophobic surface can maintain excellent hydrophobicity and excellent friction resistance after long distance sandpaper scratching.Superhydrophobic surface can effectively prevent the impact of low-temperature rain water and ice,the surface has a high anti-icing performance.After wetting with silicone oil,the surface shows super-slip characteristics,which shows good drag reduction performance.