Research On The Corrosion Mechanism Of Galvanization Vessel And Its Resistent Zinc Coatings

On the basis of primary experiment, further optimizing technical processing of plasma spraying Al₂O₃ ceramic coating, choosing the proper spraying parameters, acquiring the Al₂O₃ ceramic coating of highly bond intensity, making a preparation the ceramic coating which can prevent from corrosion of galvanizing zinc.First, the corrosion mechanism and the effect of carbon content on corrosion of low carbon steel at 500℃ in the galvanizing zinc is analyzed by metallogrophic photo, SEM and XRD in this paper. The experiment indicates that Fe and Zn form Γ, δ₁, ζ compound in turn through reaction diffusion.The strength of the δ₁ is so low that they are cline to crack and brush off into galvanizing zinc by the interface stress and thermal convection. In addition;the more carbon content, the thicker δ₁ and the faster corrosion is. On the one hand, Fe atom is dissolved in the galvanizing zinc, on the other hand, δ₁ is consumed through dropping into the galvanizing zinc. The corrosion amount is summation of the both.Second, it prepared the sample with plasma spraying Al₂O₃ ceramic coating, which can prevent from the corrosion of galvanizing zinc. This experiment sprays the FeCrAl bond coatings after spraying the sand onto the Q235 steel, which is the base of the coatings, then spraying the Al₂O₃ ceramic coating. Through what have done above, the sample have the high interface intensity. It is founded that in the course of the experiment, the ceramic coating cannot be wetted with galvanizing zinc at the beginning. The coatings which segregates the steel and galvanizing zinc plays a role in preventing from the reaction diffusion. However, after a long time immerging the case that galvanizing zinc can be adhere to the surface of ceramic coating. Analyzed by metallogrophic photo, SEM and XRD, there are some compound such as ZnO·Al₂O₃, 3ZnO·47Al₂O₃ and4ZnOllAl203 that is the production resulting from reaction between galvanizing zinc and AI2O3 ceramic coating and the produced process of these compound correspond to the content of Zn.