Question

How the nature of oxide films affects the corrosion.Discuss with suitable

example​

Answer 1

Answer:

Corrosion of metals involve electrochemical reaction with electron transfer. With the oxide layer building, it could be barrier for the electron or ion or O tansfer which would reduce the electrochemical reaction thus acting as protective layer. The protectiveness depends on the nature of oxide layer and difiusion of ions or species through this oxide layer which would react with base metal. (The Diffusion could be inner or outer or sometimes both i.e. The base metal could diffuse out or reacting species like oxygn or hydrogen could diffuse in)

Usually a non conducting non porous layer and less impurity layer would act as excellent corrosion resistance layer like TiO2 or Al2O3.

Answer 2

Answer:

The passive oxide films on metals enable the self-protection of metals against corrosion in aqueous environments. At anodic potentials, oxide films grow on metal surfaces; while at cathodic potentials, the oxide films dissolve.

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