Rust is iron oxide that incorporated water into the crystal structure. There is anhydrous iron oxide- think of a black fireplace poker, or a gun barrel. That black iron oxide is magnetite, it is a fairly good protective coating against corrosion. Rust incorporates water into the crystal structure, which makes rust expand like popcorn, and flake away, exposing fresh metal to air and water.
Rust is iron oxide. Most metals that are exposed to oxygen in the air will react with it and “rust” in some way, though it’s not called rust unless the metal is iron specifically. Some metals, like aluminium and copper, the oxide (rust) covers and insulates the rest of the metal from air, so it forms like a protective layer. But iron rust is porous, and absorbs moisture and oxygen, so more and more of the iron rusts.
Examples of other oxides: carbon dioxide, silicon oxides (rocks, sand), aluminium oxide (sapphire, ruby), nitrous oxide.
Latest Answers