| The superhydrophobic interface prepared on the metal surface has excellent performances such as the self-cleaning,weather resistance,anti-icing,low adhesion and high corrosion resistance.It is widely used in the fields containing the industrial and agricultural production,construction industry and the pipeline transportation.Inspired by the superhydrophobicity of natural animals and plants,the researchers found two necessary conditions for preparing the superhydrophobic interface.One is the chemical with low surface energy,and the other one is the multi-layer composite structure in the micro/nano scale.At present,the preparation of superhydrophobic surface film is mainly concentrated on the copper,magnesium,aluminum and its alloy,while the preparation of superhydrophobic surface film based on carbon steel is seldom reported.In this paper,Q235 carbon steel as matrix material,which is cheap and widely used,a self-assembled silane film forming agent suitable for carbon steel was screened on the surface of the silane film.The superhydrophobic surface film was prepared by hydrothermal method and its related service properties were studied.The specific research results are as follows:(1)Three self-assembled coatings of perfluorodecyltrimethoxysilane(FAS),dodecyl mercaptan(NDM),and(3-mercaptopropyl)trimethoxysilane(PropS-SH)can improve Q235 carbon steel to varying degrees on hydrophobicity and corrosion resistance.the contact angles of the surface with water droplets are: 109°,108° and 88°,respectively.The corrosion inhibition efficiency of the three coatings on carbon steel is FAS > PropS-SH > NDM.When the concentration of FAS is 2%,and the self-assembly reaction time is 6 h,the contact angle is 109°and inhibition efficiency is 98.8 %.(2)Quantum chemical calculations show that charge of the F atom on the FAS is the most negative during the researched three silane agents,the frontier orbital energy level difference(?E)of the FAS is the smallest,and the ?E of NDM is the largest,so the electronic transition in the FAS molecule is the easiest,and it is easier to adsorb on the carbon steel surface,the efficiency of the corrosion inhibition is higher.The results of quantum chemical calculations are consistent with the results of electrochemical tests,which explains that why the corrosion resistance of FAS is higher than that of the other two silane agents.(3)The hydrothermal method is used to construct a rough micro-nano-scale structure on the surface of carbon steel,the effects of hydrothermal reaction temperature,hydrothermal solution concentration and hydrothermal reaction time on the surface morphology of carbon steel were studied,combined with FAS self-assembly surface treatment,reduce the free energy of the surface.The research shows that when the concentration of ethylenediamine in hydrothermal solvent is 3.00 mol/L and the reaction is carried out at 140°C for 6 h,the superhydrophobic film with a contact angle of 152°is successfully prepared.(4)The salt spray test was used to simulate the marine atmospheric corrosion environment.The time-domain spectra of electrochemical noise show that the corrosion resistance decreases with the extension of corrosion time.The corrosion resistance of superhydrophobic samples is the strongest in the first 4 hours of salt spray reaction.After 4 hours,the surface corrosion of superhydrophobic samples was the most serious.However,after the superhydrophobic surface was left in the air for 60 days,the surface contact angle was stabilized at 139° from 152°,and still had good hydrophobicity.Continuous optical photographing showed that the superhydrophobic surface had lower adhesion properties;In the self-cleaning test,it was shown that the water droplets can carry away dust on the superhydrophobic surface and the surface remain dry,have good self-cleaning performance. |
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