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Corrosion, Wear, and Degradation of Materials
Published in Mahmoud M. Farag, Materials and Process Selection for Engineering Design, 2020
Anodic protection can only be used for metallic materials that passivate and is based on the formation of a protective passive film on the surface to be protected by externally impressed anodic current. A potentiostat is used to control the anodic current, which is normally very small. The high installation cost is a disadvantage of this method. The following example illustrates the use of sacrificial anode in corrosion protection.
Introduction to Corrosion
Published in S.K. Dhawan, Hema Bhandari, Gazala Ruhi, Brij Mohan Singh Bisht, Pradeep Sambyal, Corrosion Preventive Materials and Corrosion Testing, 2020
S.K. Dhawan, Hema Bhandari, Gazala Ruhi, Brij Mohan Singh Bisht, Pradeep Sambyal
Anodic protection is also one of the recent developments in the field of corrosion control. The most extensive use of anodic protection was found in protecting, storage and handling of sulfuric acid. It can be used to control the corrosion of metals that exhibit the tendency to form a protective passive film. When anodically polarized from its free corrosion protection, considering the potential of the metal is maintained in the range which leads to the formation of the passive layer on its surface, then the corrosion current density becomes very low and stable. The passive layer formed on the surface of metals show electrical resistivity, and is relatively insoluble in the chemical environment. The failure of electrical supply leading to the depassivation is one of the major disadvantages of this method. Conducting polymers have also been used as anode materials for piplines with deteriorating coatings. Gibson et al. (1993) have elaborated the use of conductive polymeric cable anodes that eliminate the problems of conventional groudbeds.
Materials Selection Template
Published in David A. Hansen, Robert B. Puyear, Materials Selection for Hydrocarbon and Chemical Plants, 2017
David A. Hansen, Robert B. Puyear
Anodic protection is used in a few specific applications such as with stainless steel acid coolers in sulfuric acid plants. Cathodic protection is widely used to protect metallic structures exposed to a variety of environments, including internal and external exposure. If either cathodic or anodic protection is specified, their use must be integrated into the design of the equipment to be protected. Electrode (or sacrificial anode) placement is very important, as is designing to avoid shielding effects. Also, electrical isolation of the protected surfaces must be included in designs. Specific requirements and techniques for anodic and cathodic protection are outside the scope of this book.
Electrochemical synthesis and corrosion behaviour of polyaniline on stainless steel in sodium hydroxide solutions
Published in Chemical Engineering Communications, 2021
A. M. Abdel-Gaber, B. A. Abd-El-Nabey, E. Khamis, R. M. Salman, H. T. Rahal, Z. El Morr
Anodic protection mechanism is widely used to describe protection of metals in the presence of polyaniline based coatings. It means that polyaniline metal interface is modified to produce passivating layers with charge transfer reaction occurring between the metal and polyaniline. The anodic protection mechanism is recognized by moving of corrosion potential to passive region for the chosen metal and corrosion environment. This means that, in order to achieve passivation, the corrosion potential must be shifted anodically (ennobled), to the passive region. However, the value of the passivation potential is dependent on the composition and nature of the corrosion media and type of the coated metal or alloy (Kinlen et al. 1997; Gvozdenović et al. 2012).