Investigation of the Effect of SiO2 on Corrosion Resistance of Galvanized Coating

In the present work the effect of SiO2 on corrosion resistance of hot dip galvanized coating on low carbon steel was studied.At first, conditions of forming a good galvanized coating with suitable thickness obtained and with use of SiO2 particles of under 50 microns particle size, the composite galvanized coating formed.The SiO2 particles added in fluxing step to flux bath and then galvanizing process was performed. To study the behavior of coatings, different electrochemical techniques such as open circuit potential measurements, anodic polarization and salt spray test used. The effect of SiO2 on surface morphology and thickness of galvanized coating was studied using scanning electron microscopy and optical microscopy.According to results of salt spray test, corrosion rate of coating obtained from flux solution containing 0.1 percent SiO2 particles, in compared with the pure zinc coating, decrease about 58 percent. According to result of this research, decrease in coating thickness about 34 percent and modification of phase structure of galvanized coating are the important results of presence of SiO2 in coating that increase the corrosion resistance of coating.