Effect of sodium silicate pretreatment on phosphate layer: Morphology and corrosion resistance behavior

摘要

Phosphating is a widely adopted treatment in industry for many purposes. In this paper, carbon steel was pretreated with sodium silicate before phosphating. X-ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical measurements were used to evaluate the pretreatment effect by sodium silicate on the phosphating layer. The results demonstrate that the phosphate layer pretreated by sodium silicate has a better corrosion resistance as compared with the un-pretreated ones. More compact and uniform coatings composed of finer crystals were obtained with the pretreatment of sodium silicate.