Preparation And Properties Of Self-healing Superhydrophobic Coating On Carbon Steel Q235

As a kind of engineering material,carbon steel plays an irreplaceable role in industrial,construction,machinery,and aeronautical applications.However,the low corrosion resistance in atmospheric environment has aroused wide attention.It has caused enormous financial losses,environmental contamination,and even resulted in various catastrophic accidents.There are many different techniques for preventing the corrosion of metals.Because of its low cost and simple preparation method,coating protection is one of the most effective ways to develop anticorrosion systems.However,traditional anticorrosive coatings,such as polyurethane and epoxy resins,are usually hydrophilic,which makes it easy for corrosive ions to penetrate the coating,greatly reducing the service life of the metal.In addition,once the coating layer is damaged from physical scratches,the coating will lose their protective barrier against corrosive liquid.Therefore,exploiting passive and active corrosion resistance is required for practical applications.In this study,we have prepared two kinds of self-healing superhydrophobic coating based on dual actions.The superhydrophobic surface could provide unexceptionable benefits to withstand the osmosis of corrosive ions,because the surface microstructures can trap air within solid-liquid interface which provides an extra barrier for the carbon steel.Once the coating is damaged from physical scratches,the self-healing system can repair the damaged area and provide superior active corrosion inhibition for the carbon steel.The specific research content of this paper is the following two parts:1.In this work,we synthesized a polyvinylidene fluoride（PVDF）coating with both superhydrophobicity and self-healing properties on metal anticorrosion through an ordinary replica molding method by mixing 2-mercaptobenzothiazole（MBT）loaded halloysites（HNTs）and hydrophobic Si O₂ particles with the polyvinylidene fluoride（PVDF）matrix.The self-healing superhydrophobic coating with columnar secondary structure was successfully prepared by the method of template duplication.UV-Vis spectra confirmed that the MBT release rate in both alkaline and acidic environments was faster than that under neutral environments.Thus,the MBT release was p H-dependent and especially important for corrosion protection as it was conducive to repair the corrosive areas.The contact angle（CA）test shows that the superhydrophobic surface has excellent stability to acid,alkali and Na Cl solution,etc.,which can keep the superhydrophobic property when soaked in p H=4,10 and3.5 wt%Na Cl solution for 6 h,respectively.Electrochemical test results show that the prepared coating has the best corrosion resistance during the entire immersion test due to the synergistic effects of the passive superhydrophobic barrier and the active corrosion inhibition.2.Herein,we prepared a coating with mechanochemical robustness and efficient corrosion protection by blending polytetrafluoroethylene（PTFE）powder and wax with modified epoxy resin through a simple method to endow the coating superhydrophobicity and valid self-healing property.CA test illustrated that the coating maintained superhydrophobic performance even after soaking in 1 M HCl/Na OH solution for 15 d,3.5 wt%Na Cl solution for 20 d,30 times of tape peeling and 50 times of sandpaper wear,respectively,indicating that the coating had strong chemical stability,mechanical stability.EIS test results showed that the coating exhibited the best corrosion resistance both intact and after scratches.At the same time,Tafel curve and ICP test results showed that the introduction of paraffin wax gave the coating multiple reparability and reparation durability,and the reparation durability increased by 3 times compared with the traditional corrosion inhibitor system.This scheme not only solves the instability of superhydrophobic surface,but also solves the problem that the traditional self-healing coating can not be repaired durability.