Study On The Modification Of Zinc Rich Primer On Q235 Carbon Steel

Because of the high strength and the low cost, carbon steel was widely used in the industrial, construction and other industries. As we all know, carbon steel will be corroded when there is Corrosion medium around it. So, it is very important to improve the corrosion resistance. A zinc-rich primer based on the mechanism of sacrificial anode-type cathodic protection was prepared in previous works, and was applied on carbon steel. This kind of primer can improve the corrosion resistance to some extent, but the zinc particle in the zinc rich primer react too fast which will lead to the time of sacrificial anode-type cathodic protection shorter. In this paper, we prepared three kinds of zinc rich primer which can extend the time of sacrificial anode-type cathodic protection, and improve the corrosion resistance of zinc rich primer.We prepare a new zinc rich primer by replacing zinc particles in the primer with 5wt.% 8-hydroxyquinoline. EIS、FT-IR and SEM are used to study the effect of 8-hydroxyquinoline on the corrosion resistance of zinc rich primer. The Rct of ZnRP-HQ increases and the Qdl decreases, which result in the corrosion of Zn particles inhibited. Additionally, the Rc of ZnRP-HQ increase, Qc and P decrease. The corrosion products may block the defects in the primer and enhance the barrer property of ZnRP-HQ, which further increase the corrosion resistance of the ZnRP-HQ.A new zinc rich primer was prepared by adding ZnO in various weight fractions at 60% PVC. ZnO can block the micropore in the primer, and inhibit the infiltration of electrolyte. Furthermore, the formation of a p-n junction between zinc and ZnO permits the flow of electrons and can very well control the electrochemical reaction of corrosion. In a word, the addition of ZnO effectively decreased the corrosion rate of zinc particles and extended the time of cathodic protection, and it improved the corrosion resistance of zinc rich primer.Nano-ZnO were added to the zinc-rich primer in various weight fractions to modify the primer. Nano-Zno can block the micropore in the primer, which lead to the resistance of coating improved. What’s more, the modified primer has higher charge-transfer resistance and lower electronic double-layer capacitor. This means the corrosion rate of zinc particles and reaction areas decreased. Nano-ZnO prolonged the time of sacrificial anode-type cathodic protection, and improved the barrier property. The best corrosion resistance was obtained at 2wt.% nano-ZnO addition.