Difference between metal passivation and corrosion product protection
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The book \"Corrosion and Protection of Process Equipment\" states that a metal’s corrosion resistance is primarily reflected in three aspects: 1) thermodynamic stability, 2) metal passivation, and 3) the protective properties of the corrosion product film. As for the second and third aspects, I think they are similar – isn’t the passivation film also an oxidation product, and therefore part of the corrosion product film? Then why is it considered different from the corrosion product film?
The passivation film is the result of treating the product with a strong acidic oxidant after it has been manufactured, while the corrosion product film arises from the corrosion of the metal surface by the medium during use; their formation mechanisms are different
Their functions are also different; sometimes passivation serves a protective role