Effect of Sn on corrosion resistance of corten pipe under marine atmospheric environment

Sn is often used in corrosion inhibitors, and it is found that Sn can play a better role in corrosion inhibition. At present, it is a relatively new research field to study the effect of Sn addition on corrosion resistance of corten pipe.

A wet-dry alternating accelerated corrosion test was designed to investigate the corrosion resistance of Sn-containing corten pipe under high chloride ion content. The results show that adding a small amount of Sn can play a greater role than adding Cu and Ni. It can be found by electrochemical test that because of the separation of cathode and anode with higher Cl- concentration, Fe2+ is oxidized to Fe3+. The accumulated Cl- accelerates the hydrolysis of Fe3+ to produce more H+, which reduces the pH value of the anode, and promotes the formation of β-FeOOH, which is harmful to corrosion resistance under lower pH environment.

The reason why Sn-containing corten pipe exhibits better corrosion resistance is that Sn ions can dissolve in the anode, thus inhibiting the anodic reaction and reducing the formation of β-FeOOH.