Study On Preparation And Organization Structure And Corrosion Resistance Performance Of Glass Composite Water-based Zinc-aluminum Coating

Geomet coating as a new product will replace for Dacromet coating. Geomet coating selected Silane coupling agent as substitute for chrome,it play a very significant role in the combination of ingredients, its sintering product is SiO2 that wrapped in zinc-Aluminum coating around, It have very good passivation effects on the coating. But a single silane passivation can not achieve chromate salt passivation effects. Task group members using rare earth salt and silane cooperative composite passivation have obtained the ideal effect. Although Geomet solved coating contains no toxic metal problem, but it still has some defects, such as thin coating, low hardness, poor corrosion resistance and so on. In this paper, adding glass powder in silane passivation liquid preparate the glass composite water-borne zinc-aluminum coating.By SEM, EDS, salt spray test and electrochemical experiment test method, we research organization structure and corrosion resistant properties of the glass composite water-borne zinc-aluminum coating.The three factors were selected, such as, the mesh and the dosage of the glass, the dosage of the silane. in order to optimize the formula, the orthogonal test was designed in which the results were evaluated by Primer liquid stability, primer liquid bubbles, coating appearance, coating adhesion, corrosion resistant properties. The influence of each component on coating performance was researched by extreme difference. Granular glass system:the dosage of the glass is 25g/L, the mesh is 400?, the dosage of the silane is 80ml/L; Flaked glass system:the dosage of the glass is 20g/L, the mesh of the glass is 300 ?, the dosage of the silane is 60ml/L. The coating adding different shape of glass powder form was prepared.Effect of different shape of glass powder on coating corrosion resistant performance were investigated by various tests such as natural salt spray (NSS) tests, Electrochemical impedance and polarization curve, the results show that the adding the flaked glass in coating increase the corrosion resistant properties, the salt spray corrosion resistance of the coating in terms of time is up to 3100h, which is 1.5 times of the coating with the granular glass powder, which is 5 times of the coating without glass powder.With metallograpHic microscope, SEM, The secondary electronic energy spectrum, back scattering electronic energy, X ray diffraction tested and analysed the surface and the cross section microstructure of the coating, It was shown that flaked glass powder are arranged in water-based zinc-aluminum alloy coating, which is in superimposed parallel to form a dense network structure; granular glass powder filled in the gap of the coating, a Part of the granular glass powder wrapped flake zinc, aluminum surface and surrounding. Coating contains Zn?Al?O elements and a small amount of the Si elements, Surface scanning map display Si element distribute in the periphery of Zn, Al elements.From the scanning electron microscope and the cross section of Electronic energy spectrum analysis, it initially conceived the structure model picture of glass composite water-borne zinc-Aluminum coating, the Corrosion mechanism of coating were discussed in three aspects:Barriers effect, Passivation effects, Cathodic protection, restore. Although lots of Experiment work have been done in this paper, but to further improve the corrosion resistance performance of the coating and to apply in the industrial mass production have a distance.