Study On The Effect Of Dopa Treatment On The Bonding Force And Anticorrosion Performance Of Carbon Steel Surface Coating

Coating protection technology has attracted much attention in the field of metal protection,especially environmental factors such as construction tools and high-speed multiphase flow during underground operations,which put forward higher requirements for anti-corrosion performance:higher requirements for bonding force,and coating and The adhesion of metal substrates is also an important factor affecting the service life of coatings.In view of marine mussels exhibiting super strong adhesion ability in water environment,the formation of Fe-O by a large amount of 3,4-dihydroxyphenylalanine（DOPA）in mussel byssal adhesion proteins and matrix metals Inspired by this,in this paper,by exploiting the strong coordination ability of the catechol group contained in L-3,4-dihydroxyphenylalanine（DOPA）,it can form reversible organometallic complexes with metals.It can effectively increase the adhesion of the coating and improve the corrosion resistance of the coating.（1）Graphene oxide GO and titanium oxide silicon oxide composite filler Ti O₂/Si O₂ were prepared,and the anticorrosion performance of filler ratio in acrylic polyurethane was studied.The research shows that the modulus value of the coating with 0.4%GO+1.6%Ti O₂/Si O₂ added in the resin can reach 10^6.8 ohm·cm²,and it is revealed that GO relies on the two-dimensional sheet structure to form a labyrinth effect in the coating to increase the medium penetration path,while Ti O₂/Si O₂ Improve GO dispersion performance and reduce agglomeration.Coating adhesion less than 6Mpa is the reason for the deterioration of long-term anti-corrosion performance.（2）On this basis,composite epoxy phenolic mixed resin coatings with DOPA,Ti O₂+Si O₂+DOPA,Ti O₂+Si O₂+GO+DOPA as fillers and their anticorrosion properties were prepared.The optimal filler ratio in the curing process was determined to be DOPA0.2%+TMA10%.The research shows that the modulus value of Ti O₂+Si O₂+GO+DOPA epoxy resin coating can reach 10^9.5 ohm·cm².On the basis of GO improving the anti-corrosion performance,DOPA enhances the bonding force between coating substrates through bonding,hinders the diffusion of medium and further enhances anti-corrosion.performance.（3）The hydrotalcite self-healing phenolic mixed resin coating and heavy-duty anti-corrosion coating were prepared,and their anti-corrosion properties were studied under high temperature and high pressure simulated downhole conditions and pickling environment.The research shows that under the conditions of 120℃-10kpa H₂S-1Mpa CO₂-total pressure 14Mpa-salinity 110000 and 25℃-15%HCl-2h,the hydrotalcite self-healing coating,namely LDHs-MBT coating,has good anticorrosion effect and environmental applicability.The modulus value of the modified hydrotalcite self-healing coating,that is,the DOPA-LDHs-MBT coating,can reach 10^9.1 ohm·cm²,and the LDHs-MBT filler releases the loaded inhibitor ions at the interface to reduce the Cl-concentration and form a complex with Fe to form a retardation.The corrosion film of DOPA and the metal matrix Fe element enhanced the bonding force between the coating itself and the metal matrix.LDHs-MBT and DOPA improved the anti-corrosion performance of the coating through synergistic effect.