Nanosecond Laser Preparation Of Superoleophilic And Superoleophobic Micro/nano Composite Stainless Steel

304 stainless steel is one of the most widely used alloy materials in production and life.It is particularly important to study the special wettability of its surface.Because only the surface with superhydrophobic(superhydrophilic)property is easy to be polluted by greasy substances and lose the superhydrophobic(superhydrophilic)property,so it is necessary to prepare stainless steel surface with superoleophilic or superoleophobic properties to meet the actual demand.In this paper,superoleophilic and superoleophobic stainless steel surfaces were prepared by nanosecond laser etching combined with surface modification of perfluorooctanoic acid(PFOA)aqueous solution,and the chemical composition of the surface wettability morphology was characterized.At the same time,the influence of single factor on the surface wettability was studied by using control variable method,and the optimal process parameters were obtained.In addition,the stability,self-cleaning and wear resistance of the surface of superoleophilic and superoleophobic stainless steel were investigated.The specific conclusions and results are as follows:(1)The surface of 304 stainless steel plate is etched by the mesh format scanning of nanosecond laser,and then the surface of micro-nano structure with regular order and villous texture is obtained.The wettability of samples prepared at different scanning speeds and intervals was characterized.It was found that when the laser scanning speed and interval were 1200 mm/s and 0.005 mm,the contact angles of water and hexadecane on the surface of the samples were 0°,and the droplet could completely spread out in 1.3 seconds or even 0.9 second.(2)The stainless steel surface was constructed by nanosecond laser with rough structure,and the etched surface was modified by 0.01 mo L/L PFOA solution.The contact angles of the obtained stainless steel surfaces to water,glycerin,peanut oil and hexadecane are all greater than 150°,and the rolling angles were all less than 10°,showing good superhydrophobicity.By characterizing the samples prepared with different processing parameters,the optimal processing parameters were obtained,which were scanning speed and scanning interval of 1000 mm/s,0.005 mm,soaking time 2 hours and drying temperature of 70 ℃.(3)The experiment shows that the superhydrophilic and superhydrophobic surfaces still maintain good wettability under natural conditions for up to two months,but the stability of the samples after soaking in water needs to be further enhanced.In addition,the special wettability stainless steel surface prepared by us has a good cleaning effect on flour and other dirt.Finally,the wear resistance of the sample surface was tested.It was found that the superoleophilic surface still had the superoleophilic property after being worn for 6m under the load of 100 g,and the superoleophobic surface still showed good superoleophobic property after being worn for 3 m.