Study On Graphene Composite Passivation Process And Passivation Mechanism

In order to improve the anticorrosion property of galvanized products,Zn-coating is usually passivated.The most common passivation process is chromate passivation.However,chromium ions are carcinogenic even toxic for human health and natural environment.Therefore,it is imperative to study new chromium free passivation process.In this paper,graphene oxide(GO)composite acrylic passivation process was studied,the influence of GO on the anticorrosion property of passive film was discussed,and the passivation mechanism of GO composite passive film was analysed.The passive film was fabricated by GO and acrylic acid passivation process on the surface of hot galvanized steel sheet.Through orthogonal test,the optimal formula of passivation agent was obtained and as follows: 0.02 g/L GO,400 g/L acrylic acid,9 g/L polyoxyethylene ether(JFC),13 g/L hydroxy ethylidene two phosphonic acid(HEDP),7 g/L polyoxyethylene octyl phenol ether(OP-10),3 g/L phytic acid.The optimal process conditions were obtained and as follows: pH is 3.5,passivation time is 30 s,passivation temperature is 30?,drying method is constant temperature drying.The morphology and structure of the prepared passive film were characterized by scanning electron microscopy(SEM),X ray photoelectron spectroscopy(XPS)and Fu Liye transform infrared spectroscopy(FT-IR).The results showed that the structure of the passivation film became uniformity and dense after the addition of GO.The prepared passive film is composed of GO,acrylic acid,oxides and hydroxides of zinc.The anticorrosion property of the film was studied by the contact angle test,the neutral salt spray test and the electrochemical polarization curve test.With the addition of GO,the contact angle increased by 32%,indicating that the hydrophobicity of the passivation film was improved.The corrosion voltage of the film immersed in 3.5 wt% NaCl solution increased,the corrosion current density of it decreased,and the salt fog time increased about 20%.The results showed that the performance of the passive film has been greatly improved.