What Does Corrosion Resistance Mean?
Corrosion resistance refers to the resistance a material offers against a reaction with adverse elements that can corrode the material. Various materials have this property intrinsically, depending upon their corrosion resistance rate. Alternatively, some methods or treatments can be used to resist corrosion, such as painting or hot dip galvanizing, or a combination of these methods with coating.
Corrosion is a process in which a material is oxidized by substances in the environment that cause the material to lose electrons. Corrosion resistance is the capacity to hold the binding energy of a metal and withstand the deterioration and chemical breakdown that would otherwise occur when the material is exposed to such an environment.
Corrosionpedia Explains Corrosion Resistance
Usually the resistance to corrosion is expressed in terms of the corrosion rate and measured in units of millimeter per year or "mils." These measurements for resistance to corrosion attack are taken in a particular environment at defined operating conditions, pressure, temperature and fluid velocity.
Besides intrinsic corrosion resistance, a metal's resistance to corrosion can be increased by applying different methods such as cathodic protection, coating, painting and applying a corrosion inhibitor. There are no materials that are resistant to all corrosion in all environments. Materials must be matched to the environment they will experience. Corrosion resistances for metals are estimated and data is used to check the sustainability of a metal in a particular environment.
Protective coatings are the most widely used corrosion control technique. Essentially, protective coating materials are a means for separating the surfaces that are susceptible to corrosion attack. Another method, cathodic protection, interferes with the natural action of electrochemical cells that are responsible for corrosion. Cathodic protection can be effectively used to resist corrosion of surfaces that are immersed in water or exposed to soil.
Corrosion resistance is an important factor to consider when selecting materials for corrosion control. The materials most resistant to corrosion are those for which corrosion is thermodynamically unfavorable. Some metals have naturally slow reaction kinetics, even though their corrosion is thermodynamically favorable. These include metals such as zinc, magnesium and cadmium. Thus, a material's own resistance to corrosion or protective methods to arrest corrosion fall under the category of corrosion resistance.