Preparation And Properties Of Multi-stimulus-responsive Intelligent Anti-corrosion Coatings

Metal materials have received extensive attention from all walks of life due to their excellent electrical conductivity,thermal conductivity,low cost and high strength.Q235 carbon steel is one of the most commonly used metal materials in open-air structures.Because of its low cost and good mechanical strength,it is often used to manufacture various equipment and metal structures.But for metals,there is often a huge threat,that is,metal corrosion.The problem of metal corrosion is a dark cloud that lingers on the heads of countries around the world,which has brought great losses to various countries,including economic aspects,but also threatening human health and life to a certain extent.In view of the great importance of coastal areas to human society,the problem of metal corrosion in coastal areas is particularly relevant.Carbon steel often inevitably faces various corrosion problems in harbor structures,plates and other sites.About half of the world's population lives in coastal areas,and the industrialization of developing countries is often concentrated in production plants near the ocean.For many years,it has been believed that marine chlorides dissolved in the water-containing metal interlayer will greatly increase the conductivity of the electrolyte on the metal surface and will further damage the passivation film on the metal surface.Therefore,how to prevent or slow down metal corrosion is imminent,and scientists have studied a variety of metal corrosion prevention methods.Among the many methods to inhibit metal corrosion,organic coatings have been well received by corrosion workers as a classic method.Organic coatings have many advantages,such as strong corrosion resistance,excellent wear resistance,and low cost.However,the coating is prone to cracks or defects,and then the metal matrix will be exposed to oxygen,water and corrosive ions to a certain extent,which will eventually lead to the loss of corrosion protection.Therefore,in order to improve the long-term corrosion resistance of the coating,a simple method is to directly incorporate the corrosion inhibitor into the coating to achieve the inhibitory effect.However,corrosion inhibitors may have side reactions with the resin substrate,thereby affecting the service life of the coating.Therefore,in order to overcome this problem,the corrosion inhibitor is encapsulated in micro-nano containers and nano-containers,such as mesoporous silica nanoparticles,etc.,and then incorporated into organic coatings to solve this problem.This is the intelligent self-healing coating.In order to effectively solve the protection problem of Q235 carbon steel,this work designed a variety of p H-responsive micro-nano containers and added them to the epoxy coating.Through FESEM,TEM,Zeta potential,BET test,EIS,EDX spectrum,XPS spectrum,FTIR,UV-Vis and other instruments,the smart micro-nano container designed in this work is characterized.The specific research content is as follows:Part 1,the layer-by-layer self-assembly technology is used to modify the multi-layer polyelectrolyte multilayer film containing benzotriazole(BTA)on the Ca CO₃ particles.Secondly,the polyaniline nanomaterial loaded with sodium alginate is synthesized,and the two are mixed incorporated into epoxy coating.BTA molecules and other corrosion inhibitors caused by mechanical damage or local p H changes are released into coating defects.Ca CO₃ particles have many advantages,such as low cost and strong ability to sense local acidification.Polyaniline has been proven to be an effective conductive polymer anti-corrosion material,which can form a metal oxide layer on the surface of ferrous metals and non-ferrous metal alloys.Sodium alginate(SA)is an environmentally friendly edible adhesive with potential corrosion resistance.The modulus of the scratched coating after immersing in 3.5 wt.%Na Cl solution for 48 h is 1.5×10⁶.Part 2,due to the poor compatibility of calcium carbonate,polyaniline and epoxy resin,and the complex preparation process of composite materials,work two prepared mesoporous silica nanoparticles(MSNs)modified with Zn O quantum dots.Then load BTA molecules.Unlike calcium carbonate,polyaniline and epoxy resin,which lack compatibility,mesoporous silica nanoparticles have good compatibility with epoxy resin.Here,Zn O quantum dots can not only dissolve under acidic conditions,but also In this way,BTA molecules are released and the metal self-repair is realized.Mesoporous silica nanoparticles(MSNs),as a kind of mesoporous materials,are widely used in the fields of drug release,corrosion protection,etc.by virtue of their low cost,easy production,high specific surface area and high loading rate.At the same time,the electrochemical performance and anti-corrosion self-repairing ability of the coating were studied in 3.5 wt.%Na Cl solution.The modulus of the coating sample after immersion for 48 h can reach 1.5×10⁵.Part 3,due to the complex preparation process of the composite materials in the first and second tasks,it is time-consuming and labor-intensive.Therefore,in the third task,the mesoporous silica nanoparticles loaded with the corrosion inhibitor BTA molecules were prepared by the"one-pot method"and the surface was modified Tannic acid and iron complex(TAC),because the complex constant of tannic acid and iron is related to the p H of the environment,the nanocontainer prepared is sensitive to low p H environment,so that the corrosion process occurs At this time,the release of BTA molecules can be realized,and the metal self-repair can be realized.At the same time,the electrochemical performance and anti-corrosion self-repairing ability of the coating were studied in 3.5 wt.%Na Cl solution.The modulus of the coating sample after immersion for 48 h can reach 4×10⁵.