Study On Anti-bacterial And Anti-Corrosive Functional Composite Coating

With the continuous improvement of the level of science and technology,the technical content of coatings is getting higher and higher,and the scope of application is getting wider and wider.Anti-corrosion paint refers to a type of liquid or solid,material that can form a thin film on the surface of an object to prevent corrosion and protect it under certain conditions.It has the outstanding characteristics of simple construction,strong adaptability and low cost.In recent years,with the rapid development of petrochemical,transportation,construction and marine industries,some extremely special corrosive environmental conditions have appeared,such as poor airtight ventilation or long-term water accumulation,which makes bacteria easy to breed.Under such environmental conditions,single-function anti-corrosion coatings can no longer meet the needs of use,and there is an urgent need for anti-bacterial,antibacterial and other functional composite anti-corrosion coatings.According to the technical requirements of anti-bacterial and anticorrosion composite coatings,this thesis carried out the research of solventbased and water-based anti-bacterial and anti-corrosion composite coatings,prepared coatings with dual functions of anti-bacterial and anti-corrosion.The anti-bacterial,anti-corrosion and mechanical properties of the layer were tested and characterized,focusing on solving the problem of poor compatibility between the anti-bacterial and anti-corrosion properties of the coating,and successfully realized functional compounding.The main research contents and results are as follows:1.By adding quaternized polyethyleneimine(QPEI)to the epoxy coating,a solvent-based anti-bacterial and anti-corrosive composite coating was prepared,which was tested by scanning electron microscope(SEM),laser confocal microscope and electrochemical impedance spectroscopy(EIS).Means,the effect of adding 1%,3%,5%(wt%)QPEI on the microstructure,mechanical properties,anti-bacterial properties and corrosion resistance of the coating was studied.The test results show that after adding QPEI to the epoxy coating,the coating has a certain anti-bacterial performance.When the addition amount is 1wt%and 3wt%,the anti-bacterial rate reaches 96%and 100%,respectively.After continuing to increase the amount of addition,it is found that QPEI has an impact on the curing process of the epoxy coating and reduces the anti-corrosion performance of the coating.Through the comparative analysis of the comprehensive performance of the coating,it is found that when the additive amount is 3wt%,the coating has the best anti-bacterial and anti-corrosive performance.Specifically:the anti-bacterial rate reaches 100%.After soaking in 3.5wt%NaCl solution for 65 days,the coating The low-frequency impedance value of the layer is still stable at 109(?·cm2),showing good corrosion resistance.2.By adding modified nano-zinc oxide(ZnO NPs)and water-based QPEI to the water-based epoxy coating,the water-based ZnO NPs coating and the water-based QPEI coating were prepared respectively,and the effects of different contents on the mechanical properties and anti-corrosion properties of the coating were analyzed.The test results show that the addition of QPEI can enhance the anti-bacterial performance of the water-based coating,but it will cause the mechanical properties and corrosion resistance of the coating to decrease.The addition of ZnO NPs can significantly enhance the contact angle and anti-corrosion performance of the coating,and when the addition amount is 0.3wt%,the contact angle reaches 92?,and the low-frequency impedance value after 30 days of immersion is still stable at 109(?·cm2).The above shows that the waterborne epoxy coating with 0.3wt%ZnO NPs has better anti-corrosion performance.3.ZnO NPs and water-based QPEI were introduced into the coating at the same time by blending method to prepare a water-based anti-bacterial and anticorrosion composite coating.The microstructure of the coating was analyzed by SEM,plate colony method,EIS,polarization curve and immersion experiment.Appearance,antibacterial properties,anti-corrosion properties and mechanical properties.SEM and mechanical performance test results show that after adding ZnO NPs,the functional composite coating and the substrate are more closely combined,and the mechanical properties are also enhanced to varying degrees.The anti-bacterial results show that QPEI can significantly enhance the anti-bacterial ability of the coating,and QPEI and ZnO NPs have a synergistic anti-bacterial effect,and the anti-bacterial rate of EP/QPEI(2wt%)/ZnO NPs coating reaches 100%.EIS,polarization curve and immersion experiment results show that the low-frequency impedance modulus of EP/QPEI(2wt%)/ZnO NPs coating is 3.90×109(?· cm2),and its value remains at 108(?·cm2)even after being immersed for 30 days,which shows that the coating has the most excellent long-term corrosion protection effect.This is mainly due to the fact that ZnO NPs enhances the compactness of the waterbased coating and increases the tortuosity of the diffusion path of the corrosive medium,so it can effectively prevent the diffusion of the corrosive medium and obtain an excellent anti-bacterial and anti-corrosive composite coating.