Evaluation of the Anticorrosion Properties of Passivation Solution Containing Different Metal Ions Coated on a Steel Surface

The corroded metals in the world account for about 1/3 of the total every year. How to prevent metal corrosion has become a major research topic in the scientific community. Although traditional chromate passivation, phosphate conversion and other technologies can solve the corrosion problem of metals, they pollute the environment and pose a threat to human health. It is urgent to develop new green metal surface treatment technology. The unique chemical structure of silane can form a good protective layer on the metal surface and play an anti-corrosion effect, so the metal surface silanization technology is considered to be the most ideal alternative technology to prevent metal corrosion. Silane passivation solution prepared by organosilicone resin and polyurethane resin mixed with a small amount of metal ions has been used in corrosion prevention of many metals and metal alloys. This study aimed to evaluate the effect of metal ions on the anticorrosion properties of a passivation solution, which contains polyurethane resin and amino silicone resin. Zn 2+ , Cu 2+ , and Ni 2+ were separately added to the passivation solution. This solution was coated on a steel surface using a dip-coating method, and the coated samples were then exposed to 3.5 wt% NaCl solutions for several days. Scanning electron microscopy, thermogravimetric analysis, Fourier transform–infrared spectroscopy, ultraviolet, and electrochemical impedance spectroscopy techniques were conducted to investigate the morphological properties and corrosion resistance of the coatings. The results showed that the types of metal ions were important parameters that affected the corrosion resistance of the coatings. The passivation solution mixed with Zn 2+ showed better corrosion resistance than that mixed with Cu 2+ and Ni 2+ .