ruostumis

Ruostuminen is the Finnish word for rusting. It refers to the oxidation of iron or its alloys, such as steel, which results in the formation of reddish-brown flakes or powder. This process occurs when iron is exposed to oxygen and moisture.

The chemical reaction involved in rusting is complex but can be simplified as the formation of hydrated iron(III) oxide. Iron acts as the anode, where it loses electrons and becomes oxidized. Oxygen acts as the cathode, where it gains electrons and is reduced. Water is essential for the electrochemical process to occur, acting as an electrolyte.

Factors that accelerate ruostuminen include the presence of electrolytes like salt, increased temperature, and surface irregularities that create more sites for the reaction to begin. The resulting rust is porous and brittle, which can weaken the underlying metal.

Preventing ruostuminen typically involves creating a barrier between the iron and the environment. This can be achieved through coatings like paint, plating with other metals such as zinc (galvanization) or chromium, or by using stainless steel, which contains chromium that forms a protective oxide layer. Sacrificial anodes, made of a more reactive metal like zinc, can also be used to corrode instead of the iron object.