Preparation And Corrosion Resistance Of GO And VTEO Modified Zinc-nickel Coating On Low Carbon Steel Surface

Zinc-nickel coatings are widely used due to their excellent seawater corrosion resistance.Usually in order to improve the corrosion resistance and aesthetics of zinc-nickel coating,it will be chromated and passivated,but this will often pollute the environment and even cause cancer in human body,so find a substitute for zinc-nickel plating passivation treatment seems very necessary.In this paper,organosilane and graphene oxide were introduced into the zinc-nickel modified layer by one-step electrodeposition method.Zn-Ni/VTEO coating was successfully prepared on the surface of Q235 low carbon steel and GO/VTEO was prepared on the surface of Zn-Ni coating.The coating is designed to effectively slow the corrosion of the Zn-Ni coating.Studies on Zn-Ni/VTEO mixed coatings have shown that the coating consists of a bottom Zn-Ni alloy and a surface silane film.The surface particles become larger as the deposition time,the deposition current density,and the zinc-nickel composition in the plating solution increase.The cross section becomes thicker as the deposition time and the composition of zinc and nickel in the plating solution increase.When the content of silane hydrolyzate in the plating solution is more than 75%,it is difficult for Q235 steel plate to form Zn-Ni coating layer on the surface of Q235 steel plate.The surface of the mixed plating layer is mainly silane film;when the content of silane hydrolyzate is less than 33%,the surface is Zn-Ni plating is dominant,and it is difficult to form a silane film.When the content of silane hydrolyzate in the bath is 66.6%,a superhydrophobic coating will be formed with a hydrophobic angle of up to 163°..Corrosion performance tests show that the corrosion resistance of Zn-Ni/VTEO mixed coatings increases first and then decreases with the increase of deposition time and deposition current density.When the deposition time is 25min,the current density is 2.5A/dm2,and the volume ratio of silane hydrolyzate to Zn-Ni plating solution is 1:1,the corrosion current is the smallest,the corrosion potential is the highest,the corrosion resistance is the best,and the salt spray corrosion resistance time is obtained.Up to 8h Surface silane film acts as a barrier to corrosive mediaStudies on GO/VTEO mixed coatings show that the distribution of graphene oxide on the surface of the mixed coating decreases with the increase of deposition voltage,deposition time and graphene oxide content.When the graphene oxide content is more than 0.4 g/L,graphene oxide is polycondensed,and a large number of cracks occur.Graphene oxide is difficult to deposit when the graphene oxide content is less than 0.1g/L.When the deposition time is more than 300s and the deposition voltage is greater than 10v,the graphene oxide falls off in a large area.The corrosion performance test showed that the corrosion resistance of the GO/VTEO mixed coating increased first and then decreased with the increase of deposition time,deposition voltage and graphene oxide content in the plating solution.When the deposition time is 90s,the deposition voltage is 5V,and the graphene oxide content is 0.3g/L,the corrosion current is reduced by two orders of magnitude compared with the original Zn-Ni substrate.Compared with the single electrodeposited silane film,the presence of graphene oxide compensates for the defects of VTEO film,prolongs the H₂O,O₂,and Cl^-infiltration paths,and effectively reduces the corrosion of Zn-Ni coating.The mixed coating can be immersed in salt water for 96h without damage,and the corrosion resistance is improved by 8 times.