Preparation And Corrosion Behavior Of Superhydrophobic Coating On Carbon Steel

As an important engineering material,carbon steel is widely used in various fields because of its low cost and good mechanical properties,but it is prone to corrosion,which will obviously reduce the service life of carbon steel products and increase the cost of product maintenance.In order to solve this problem,polydimethylsiloxane/diatomite superhydrophobic coating was prepared on the surface of carbon steel,the corrosion protection was carried out effectively,and the comprehensive properties of the coating were further improved by adding nano-fillers.The effects of the ratio of polydimethylsiloxane to diatomite,solvent volume and dipping times on the microstructure of the coating were studied,and the formation mechanism of the coating was discussed.the effects of microstructure changes on wettability and corrosion resistance were clarified.The effects of the type,content and particle size of nano-fillers on the structure,hydrophobicity and corrosion resistance of superhydrophobic coatings were studied.The evolution of microstructure and hydrophobic properties of the coating during solution immersion were analyzed,and the corrosion mechanism of the coating was analyzed.It is found that the preparation parameters have a great influence on the properties of the coating.with the increase of the ratio of polydimethylsiloxane to diatomite,diatomite is gradually covered on the surface of carbon steel,forming a uniform and continuous micro-nano hierarchical structure.The coating reached a super-hydrophobic state.The effect of solvent volume on the coating can be divided into two aspects:thickness and density.with the increase of solvent volume,the hydrophobicity of the coating changes little,the thickness decreases gradually,the internal defects increase,and the carbon steel substrate is easy to be corroded.When the ratio of polydimethylsiloxane to diatomite is 1:2.5,the volume of solvent is 15m L,and the dipping times is 1,the contact angle of the coating is 153.84°.And the corrosion current density is as low as 2.31×10^-9A/cm 2.Compared with carbon steel,the corrosion rate is reduced by 3 orders of magnitude,and the substrate can be effectively protected for 41 days in 3.5%NaCl solution.The adhesion of the coating reaches grade 2.The coating has better comprehensive properties.The addition of nano-fillers has a significant effect on the microstructure,hydrophobicity and corrosion resistance of the coatings.the hydrophobicity and corrosion resistance of the coatings are significantly improved with the addition of TiO₂with a particle size of 15 nm and 0.3g,with antennae as high as 163.92°and corrosion current density as low as 2.56×10^-11A/cm ²,which is 2-3 orders of magnitude lower than that of the coatings without fillers.After soaking in 3.5%NaCl solution for 86 days,the coating still has a high impedance modulus of 3.31×10⁵Ω·cm²,has a continuous and better protective effect on the carbon steel substrate.