Question

The equilibrium thickness in the anodic oxidation process depends on which of the following factor?

(a) Nature of electrolyte

(b) Amount of electrolyte

(c) Magnitude of the applied field

(d) Weight of the electrode

I have been asked this question in homework.

The origin of the question is Preparation of Thin Films topic in division Preparative Methods of Solid State Chemistry

Answer 1

The correct option is (c) Magnitude of the applied field

The best explanation: During anodic oxidation, on increasing the field strength more oxide ions diffuse through the oxide layer to the metal surface and hence, the oxide layer grows thicker. An equilibrium thickness is reached after some time which depends on the magnitude of the applied field. Anodic layer may also be formed by exposure of the metal to a glow discharge.