A chemical compound of oxygen with another element. Hydrated (water-including) iron oxide is called rust; it does not cling tightly to the underlying metal, so the oxidation process is progressive and iron easily rusts away. Aluminum oxide is a hard, transparent compound which clings tightly to the underlying metal and protects it against further oxidation.
Materials formed by the reaction of elements with oxygen. In the case of soldering materials, oxides are formed by reactions between the surface metals and oxygen in the air. This process is accelerated by high temperature. Oxides vary enormously in physical properties: some are flaky and poorly adherent, such as the oxides and hydroxides found in rust, and some highly adherent, such as the aluminium oxide layer created during the â€˜anodisingâ€™ process. For soldering, the oxides of tin, lead and copper interfere with the proper wetting of solder and need to be removed or dispersed before soldering, an operation which is usually carried out by flux. See oxidation.