Corrosion characteristics of different metallic alloys in acidic medium

Abstract

Corrosion is the disintegration or loss in useful properties of metal and their alloys or material of construction into its constituent atoms due to attack of atmospheric gases resulting in to chemical (dry corrosion) or electrochemical (wet corrosion) reactions with its surroundings. Corrosion can also be defined as an electrochemical process in which oxidation and simultaneous reduction of metals takes place in a reaction in presence of an oxidant such as oxygen. Dry and wet corrosion are its two types. Formation of an oxides of metallic iron due to oxidation in solid form is a well-known example of electrochemical dry corrosion, commonly known as rusting. This type of loss of material resulting in corrosion typically produces oxide(s) or salt(s) of the original metal. Phenomenon of corrosion can not avoided but losses due to corrosion can be minimized. Almost all form of material corrodes in ways or other, such as ceramics (concrete corrosion) or polymers, although in this context, the term degradation is more commonly used. newlineCorrosion is also defined as loss in the useful property of the material due to attack of atmospheric gases. It can also be defined as the wearing away (loss) of metals due to attack of atmospheric gases (air and moisture) on the surface of metal and their alloys resulting in a chemical or electrochemical reaction. newlineEffect of atmospheric gases is different for different metallic alloys. Many structural alloys corrodes severely while other mildly depending upon a number of factors like humidity content, nature of pollutant, rate of flow etc. The rate of corrosion can be strongly affected by exposure to certain substances present in air. There are different forms of corrosion. It can be concentrated locally to form a pit or crack, or it can extended (spread) across a large area more or less uniformly corroding the surface resulting in uniform type of corrosion. Corrosion may be diffusion controlled process as it occurs mainly on the exposed surfaces of material and their alloys.