Wear And Corrosion Resistance Properties And Mechanism Of ER Composite Coatings Reinforced By Hybrids And Embedded With FACs

Epoxy Resin(ER)coating is one of the most widely used means of protection in marine equipment(Offshore wind power,Offshore oil drilling,etc.),with the advantages of small mass,simple coating process,strong bonding performance,etc.With the increasingly complex and harsh environment faced by marine equipment,it is necessary to improve the wear resistance and corrosion resistance of ER coatings to meet the current service requirements.In view of the key problems faced by the traditional research on the enhancement of wear and corrosion resistance of ER coatings,this topic focuses on the difficulties of enhancing the dispersion compatibility of fillers in ER matrix,exploring the mechanism of microscopic action of hybrid fillers in ER matrix,and enhancing the hydrophobicity of ER coating surface.Based on the synergistic effect of polymorphic fillers,fly ash microbeads(FACs)and graphene oxide(GO)were selected as fillers to enhance the wear and corrosion resistance of ER coatings.In order to optimize the filler size,the FACs were screened by particle size.Then,based on surface modification,GO-FACs hybrids were synthesized by solution blending method to further improve the dispersion compatibility of fillers in ER matrix.The morphology,chemical structure of GO-FACs hybrids fillers and the mechanical properties of hybrids/ER composites were analyzed.The results showed that FACs were successfully loaded onto GO sheets,forming a novel three-dimensional hybrids structure.Based on molecular dynamics(MD),using Materials Studio(MS),the molecular models of FACs,GO and hybrids were constructed,and the interaction energy between fillers was simulated and calculated.The interaction energy between fillers was effectively reduced,revealing the microscopic mechanism of the improved dispersion of the hybrid fillers.The hybrid/ER composites were prepared,the tensile properties and impact properties of the composites were characterized.The results show that the tensile and impact properties of hybrid/ER composites are significantly improved compared with pure ER and GO/ER composites.The optimum content of the hybrid filler in the ER matrix is 0.5 wt.%,and the optimum dispersion temperature is 40℃.The microscopic morphology of the cross-section shows that the dispersion and compatibility of the hybrid filler in the ER matrix are significantly improved compared with GO,and it can stably act as a reinforcement to resist external force damage.In order to reveal the microscopic enhancement mechanism of the mechanical properties of hybrid/ER composites,the molecular model of hybrid/ER composites was constructed by MS,and the simulation calculations of microscopic mechanical properties,interaction energy,free volume and other microscopic properties were carried out.The calculation results show that the three-dimensional hybrid structure optimizes the microscopic mechanical properties of ER composites.The hybrid filler combines the performance advantages of FACs and GO fillers,and the dispersibility and compatibility in the ER matrix are significantly improved.The free volume of the hybrid/ER composite is the lowest,which proves that the hybrid filler enhances the compactness of the ER material.The preparation process of GO-FACs/ER composite coatings was determined and then the wear and corrosion resistance of different types of filler enhanced ER composite coatings was analyzed.The results show that hybrid/ER coatings have a lower coefficient of friction and wear rate compared to pure resin coatings and GO/ER coatings.Abrasion microscopic images show better dispersion of 3D hybrids in the ER matrix compared to GO lamellae.The hydrophobicity of hybrids/ER coating surface increased.Compared with pure ER coating’ and GO/ER coating,hybrids/ER coating has better anti-corrosion performance.After three months of damp heat aging and 30 days of seawater immersion test,the hybrids/ER coating still showed an effective protective effect on the steel sheet.In order to further enhance the wear and corrosion resistance of ER coatings,a new method of surface inlaying FACs based on hybrids enhanced ER composite coatings was proposed,and the surface inlaying process was studied and improved.The microscopic morphology,wettability,wear resistance,and corrosion resistance of ER composite coatings with FACs embedded on the surface were analyzed experimentally.The results showed that FACs were embedded into the surface of the ER coating to build a microstructure with a raised hemispherical shape.The hydrophobicity of the ER composite coating with FACs embedded on the surface is greatly improved,the contact angle reaches 137°,and it has excellent mechanical durability.Compared with the hybrids/ER composite coating,the ER coating with FACs embedded on the surface has lower friction coefficient and wear rate.The corrosion resistance of the hybrids/ER coating with FACs mounted on the surface is further improved compared with the unmounted ER coating。In summary,this study successfully prepared the GO-FACs hybrid structure based on the surface modification of the filler to solve the problem of ER coating in marine environment,which improved the dispersion compatibility of the filler in the ER matrix and the mechanical properties of the ER composite.Based on molecular dynamics technology,the mechanism of action of hybrid fillers in ER matrix was revealed from the microscopic level.A new method of embedding FACs on the surface of the ER coating was proposed,and the experiments proved that the wear and corrosion resistance of the hybrids/ER composite coating with FACs embedded on the surface was further improved.This thesis will provide new methods and new ideas for the protection of marine equipment and provide a theoretical basis for the development of new wear-resistant and anti-corrosion coatings.