What Does Oxide Film Mean?
An oxide film is normally a thin layer deposited on the surface of a metal which has undergone an oxidation reaction from air or moisture surrounding the material. These oxide films are naturally produced in highly reactive materials from the top of the galvanic series. However, these oxide films can be chemically produced by exposing the surface of the material to controlled oxygen and temperature levels. Oxide films are used in the reduction of corrosion on the surface of the material by preventing further reaction. Some metal oxide films are used in making resistors and transistors.
Corrosionpedia Explains Oxide Film
Oxide films are formed from redox reactions (transfer of electrons). In the case of rusting, the oxide film on the surface of iron is a result of the interaction between oxygen and water, which forms hydrated iron (III) oxide. The composition of this byproduct differs from that of the previous state, where it cannot be affected by the same ambient conditions that resulted in rusting. Naturally occurring metals generally exist in the form of oxides since exposure to air and a moist environment stimulates the production of an oxide film on the surface.
With rusting, the surface of the material corrodes, thus causing a negative effect on the structure. In other cases the oxide film forms on the surface of a metal which is not easily flaked. This oxide film also prevents any other chemical attack on the surface of the metal, and thus is preferable for protection. Oxide films can be grown in laboratories to certain thicknesses depending on the indented application of the metal in preparation.