Study On Preparation And Corrosion Resistance Of Graphene/Metal Composite Coating

Hot dipping galvanizing alloy coating on the surface of steel is an effective anti-corrosion method for steel.In order to improve the corrosion resistance of conventional Zn-5Al(wt.%)coating and make it adapt to more complex corrosion environment,this paper attempts to add graphene(GNPs)with strong chemical inertness and impenetrability to Zn-5A1 coating to obtain a coating with better corrosion resistance.In this experiment,Zn-5A1 coating is prepared on DC01 steel by hot dipping,and Zn-5Al-xGNPs(x=0.1,0.3,0.5,0.7,1.0)(wt.%)coating is prepared on DC01 steel by the method of inert shielding gas directionally blowing-mechanical stirring-hot dipping.It is found that when the mass fraction of GNPs in the coating is 0.1%-0.7%,the GNPs can be dispersed evenly,and when the mass fraction of GNPs in the coating reaches 1.0%,GNPs will easily agglomerate.GNPs presents a slightly transparent gray flake,which is more likely to exist around the Al-based solid solution in the coating,GNPs has no obvious influence on the overall morphology of the coating and the composition of the zinc-aluminium phase.The corrosion resistance of the coating is tested,and it is found that in the neutral salt spray corrosion test,the Zn-5Al-0.7GNPs coating produces fewer corrosion products and has the lowest corrosion rate;The polarization curve shows that the self-corrosion current density of Zn-5Al-0.7GNPs coating is the lowest,which is 1.2885E-6Amp/cm2;After the electrochemical impedance test,the capacitance arc radius of Zn-5Al-0.7GNPs coating is the largest,and the impedance modulus in the low frequency region is the highest,and the charge transfer resistance reaches 23961?·cm2,which is five times higher than that of Zn-5Al coating with 4912?·cm2.The results show that the corrosion resistance of Zn-5Al-xGNPs(x=0.1,0.3,0.5,0.7,1.0)coating is better than that of Zn-5A1 coating,and the corrosion resistance of Zn-5Al-0.7GNPs coating is the best.Based on the structure and properties of graphene,the mechanism of its effect on the corrosion resistance of the coating is analyzed.It is considered that the special two-dimensional sheet structure,impermeability,hydrophobicity and good conductivity of graphene can not only act as a physical barrier to the penetration of the corrosion medium,but also make full use of the protective role of sacrificial anode.Thus,the corrosion resistance of the coating can be effectively enhanced.