Study On Passivation Process Of Acrylic Resin And Silicate In Hot - Dip Galvanized

Hot dip galvanizing technology is the most widely used in the world today and the operation is simple and convenient method in steel material surface protection.Galvanized steel is widely used in aerospace, automotive industry, construction, light industry and other fields. However, Hot dip galvanized layer liable to corrode in damp environment, forming "white rust". In order to improve the corrosion resistance of galvanized layer and prolong the service life of coating, we passivate it.Traditional chromate passivation process were banned in all countries because of its highly toxic. In this paper, on the basis of the silicate passivation technology, I finally got the chromium-free passivating process which is based on acrylic resin and silicate through single factor experiments and orthogonal experiments. The best formula and technological conditions for the passivation solution:40 ml/L acrylic resin, sodium nitrate,20 g/L,40 g/L sodium silicate, hydrogen peroxide 15 ml/L, PH value of 11, passivation temperature of 25 ℃, passivation time for 30 s, drying methods for constant temperature drying.SEM test shows that the organic and inorganic composite membrane microstructure is more uniform, dense, smooth than silicate passivation membrane. XPS test shows that main components of composite passivating film are acrylic resin, Zn4Si2O7(OH)2 · 2H2O、ZnO、 Zn(OH)2、SiO2. By copper sulfate solution spot test, salt water immersion test, salt spray test and electrochemical testing, the results showed that the corrosion resistance of passivating film has increased significantly than galvanized passivation layer, which is similar to hexavalent chromium passivation membrane. So it has a broad market application prospect.