What Does Oxidized Surface Mean?
An oxidized surface is a surface that has a thin, tightly adhering, oxidized skin (from straw to blue in color), extending in from the edge of a coil or sheet.
All metals, with the exception of the precious metals, will oxidize when exposed to oxygen and an electrolyte, such as atmospheric moisture. It is a chemical reaction of the metal surface with the oxygen present in the air that causes some of the metal to corrode (or oxidize) and form the respective metal oxide on the surface. In some metals such as steel, the corrosion products formed are very visible and loose. Metals such as stainless steel oxidize as well, forming a passive film of chromium oxide the prevents further oxidization, or rust.
Understanding the oxidization of metal surfaces is very important in corrosion studies because steel is so widely used and it must be protected against rust.
Corrosionpedia Explains Oxidized Surface
A metal oxide is a compound containing a metal and oxygen. Oxidizing metal is the formation of an oxide layer on the metal's surface. Oxidation is a chemical process by which an ionic chemical reaction occurs at the surface of a metal when in the presence of oxygen. This can happen in air or when metal is exposed to water or acids. The most common example is the rusting of steel, which is a transformation of the iron molecules on the surface of the steel into iron oxides, most commonly Fe2O3 and Fe3O4.
Methods to reduce the activity of the exposed metal surface can increase a material's corrosion resistance. Passivation only occurs if the proportion of chromium is high enough and oxygen is present.
Metal oxidation is often unwanted (such as in the case of corrosion) but under controlled conditions the oxidation of metals can be beneficial for the manufacture and performance of advanced materials.
The most widespread form of corrosion is the rusting of iron and steel. Rusting can be prevented by excluding air and water from the iron surface by treatments such as:
- Plating the iron with a protective coating of another metal
Many alloys of iron are resistant to corrosion. Stainless steels are alloys, and they do not corrode because the added metals help form a hard, adherent oxide coating that resists further attack.