Document Type : Original Article


National Petrochemical Company, Research and Technology Company, Iran


Most of the equipment used in material transportation industries, chemical and non-chemical process industries, and even most military equipment use metal base structures. Corrosion of metals, destruction of metal structure or basic alloy is an obvious thing, the consequences of which may be economic, human, environmental, or in general, the collection of these losses. All these unpleasant consequences stem from several factors, one of the most important and main mechanisms is the phenomenon of corrosion of metal atoms (loss of valence layer electrons of the metal in the presence of oxidizing agents) and their transformation into ions, which are forced to leave the metal structures and entering the surrounding solution or electrolyte. These phenomena lead to the loss of metal mass, which can manifest itself as a decrease in overall thickness (uniform corrosion) and progressive holes in the depth of the metal (pitting corrosion). In general, corrosion is the cause of mechanical failure and the reduction of structural strength is a target process, because its effects cause the equipment to be destroyed and taken out of service against a mechanical stress higher than the threshold of tolerance, followed by economic losses, human casualties and the environment biologically obtained. Historically, researchers and engineers have always faced the phenomenon of corrosion, and depending on the era in which they lived and the level of science and technology at that time, they used one of the methods to protect the surface against corrosion and other destructive mechanisms of the equipment's materials. Covering the surface with a resistant layer against the penetration and attacks of corrosive and destructive agents is one of the most traditional methods of protecting materials against the destructive behavior of the environment that surrounds a device during its lifetime.


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