The thin layer of tin on tin-plated steel cans is less easily oxidized than iron, and it
protects the steel underneath from corrosion. It is deposited either by dipping the can
into molten tin or by electroplating. Copper is also less active than iron (see Table 21-2).
It is sometimes deposited by electroplating to protect metals when food is not involved.
Whenever the layer of tin or copper is breached, the iron beneath it corrodes even more
rapidly than it would without the coating, because of the adverse electrochemical cell that
is set up.
21-18 Corrosion Protection 875Rust is a serious economic problem.Protection against corrosion. (Left) Galvanized objects are steel coated with zinc. (Right)
Steel is plated with chromium for appearance as well as protection against corrosion.