Preparation And Properties Of Superhydrophobic Surface Of 304 Stainless Steel Substrate

Stainless steel materials with super-hydrophobic properties have broad application prospects in industrial and marine industries,mainly because superhydrophobic surfaces have excellent resistance to drag reduction,anti-icing,and self-cleaning.At present,a variety of methods for preparing superhydrophobic surfaces have been successfully developed,but the related research on wear resistance and corrosion resistance is relatively small,and thus its use range is limited.The superhydrophobic surface needs to have a micro-nano structure with low surface energy,and the criterion is that the contact angle is in the interval[150°,180°],and the rolling angle is in the interval[0°,10°].In this paper,three superhydrophobic surface preparation methods were studied and their corrosion resistance and wear resistance were studied.In this paper,the surface micro-nano structure of 304 stainless steel was firstly constructed by chemical etching.The corrosion solution was prepared by ferric chloride,phosphoric acid,hydrochloric acid and hydrogen peroxide.The influence of corrosion time on its surface structure and contact angle was investigated.The time is 2-6 min with an interval of 1 min.Studies have shown that the surface of the sample after corrosion is a hydrophilic surface.The above samples were surface-modified with perfluorodecyltriethoxysilane?PFDS?to reduce the surface energy for a modification time of30 min,and then the contact angle was measured.The experimental results show that the sample has the best superhydrophobicity when the etching time is 5 min.At this time,the contact angle of the sample is 156°and the rolling angle is 7.4°.The experiment further studied the corrosion resistance and wear resistance of the sample with 5 min corrosion.The corrosion rate of the super-hydrophobic sample was 1/8 of that of the original 304 stainless steel,and the corrosion resistance was improved;but the surface wear resistance was poor.Applying a pressure of 1 kpa to the sample on 1000#sandpaper,the superhydrophobic property is lost when the friction distance reaches 10 cm.On the basis of the chemical etching method,physical vapor deposition method is combined to improve the wear resistance and corrosion resistance of the superhydrophobic surface structure.A 304 stainless steel sample etched with the above etching solution for 5min was selected as the substrate,and TiN-Ag films were deposited on the surface by magnetron sputtering for different time.The deposition time was 0.5-2 h with an interval of0.5 h.The surface of the sample after coating was modified by PFDS for 30 min.The results showed that the sample with a deposition time of 0.5 h achieved superhydrophobic effect.The contact angle was 158°and the rolling angle was 6.7°.The corrosion resistance and wear resistance of the sample were further analyzed.The corrosion resistance of the sample was better than that of the original 304 stainless steel,and the corrosion rate was 1/10 of that of the original stainless steel.In the abrasion resistance test,the friction distance exceeded 20cm.At the same time,the sample began to lose its superhydrophobic property.It can be seen that adding a layer of TiN-Ag film to the stainless steel substrate and PFDS is beneficial to improve the corrosion resistance and wear resistance of the sample.On the basis of the chemical etching method,a nano coating layer is coated on the surface thereof to improve the wear resistance and corrosion resistance of the superhydrophobic surface.The first is the preparation of nano-coating:surface modification of nano-SiO₂powder by PFDS,mainly by mixing PFDS with nano-SiO₂ powder to make modified SiO₂powder,and then modifying SiO₂ and polydimethylsiloxane?PDMS?was mixed to make a SiO₂/PDMS coating in which the amount of modified SiO₂ was 0,0.2,0.4,0.6 and 0.8 g,respectively.The 304 stainless steel sample which was etched by the above-mentioned ferric chloride corrosive solution for 5 min was used as the substrate,and the prepared SiO₂/PDMS coating with different modified SiO₂ content was coated on the surface to study the superhydrophobic property of the modified SiO₂ content.Impact.The results show that when the concentration of modified SiO₂ is 8 wt.%,the superhydrophobic property of the sample is the best.The contact angle is 165°and the rolling angle is 4.95°.Corrosion resistance was studied.The experimental results show that the corrosion resistance of this sample is greatly improved compared with the original 304 stainless steel,and the corrosion rate is 1/100 of the original 304 stainless steel.In the abrasion resistance test,when When the friction distance exceeds 60 cm,the sample begins to lose superhydrophobic properties,and the wear resistance of the superhydrophobic surface is greatly improved.