As shown in Fig. 10(f), the corrosion scale of the tin-containing steel
is dense, which can restrict the contact between solution and substrate
steel efficiently. And the dense corrosion scale also can inhibit the anodic
reaction. The compounds of SnO and SnO2 are regarded as immune in
aqueous, and SnO2 can hardly dissolve in acid and alkali solutions.
Besides, SnO2 can remain stable in dilute acid and alkali solutions [21].
These can make the rust layer of tin-containing steel stable, protective
and have a better corrosion resistance. The results of XRD show the difference
between the two steels at iron oxides and oxyhydroxides.