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Corrosion: Introduction
Published in Hatem M.A. Amin, Ahmed Galal, Corrosion Protection of Metals and Alloys Using Graphene and Biopolymer Based Nanocomposites, 2021
Anjali Peter, Sanjay K. Sharma
This process happens in the electrically conductive environment. Deformation comes into existence due to the potential difference between the metals. If the active noble metal acts as the cathode with higher surface area and the less noble metal acts as the anode with less surface area, in this case, a large cathodic reaction takes place with the combination of higher anodic reaction. This process upsurges the corrosion rate with major harm to metal. The electromagnetic series (Galvanic series) is used to predict the tendency of metal to galvanic corrosion.
Joining Technologies
Published in Raghu Echempati, Primer on Automotive Lightweighting Technologies, 2021
The electrochemical reaction that takes place is an oxidation-reduction reaction (redox). An oxidation reaction is the removal of one or more electrons from an atom, ion, or molecule; this takes place at the anode. A reduction reaction is the addition of one or more electrons to an atom, ion, or molecule; this takes place at the cathode. When a redox reaction takes place, electrons flow from one metal to another causing a current flow and, consequently, corrosion. The corrosion is concentrated at the metal that is less noble (called the anode) which can be determined using the galvanic series. The galvanic series ranks metals and alloys as to their relative electrochemical reactivity in seawater. The galvanic series is practical and essential for determining the effects of galvanic corrosion (Figure 6.42). Similar reactions take place between Fe-Cu cells.
Corrosion
Published in Mavis Sika Okyere, Mitigation of Gas Pipeline Integrity Problems, 2020
The potential difference between two different metals of galvanic coupling is the driving force of galvanic corrosion. The strength of corrosion increases as the distance within the galvanic series increases. In the sacrificial anode protection system, it is certain the galvanic distance increases between the anode and the protected structure. The larger the distance is, the more negative potential will be obtained on the protected structure.
Plant wastes as alternative sources of sustainable and green corrosion inhibitors in different environments
Published in Corrosion Engineering, Science and Technology, 2023
Nnabuk Okon Eddy, Anduang O. Odiongenyi, Eno E. Ebenso, Rajni Garg, Rishav Garg
Dissimilar electrode cell generates a driving force for galvanic corrosion. This cell consists of different metals joined together in a corrosion environment [13]. The feasibility of a corrosion reaction in a dissimilar cell will depend on the difference between the electrode potential of the different metals. Generally, the nobler (or less reactive) metals will serve as the cathode while the more active metal is the anode. Consequently, the electrode potential generated can be written as follows: Therefore, corrosion in a dissimilar cell can only be feasible if the is positive. Indicating that the driving force for the corrosion cell is the difference in electrode potentials (i.e. the galvanic series).
Corrosion Sensor for Water-Contaminated Grease
Published in Tribology Transactions, 2020
Nicholas Dittes, Mikael Sjödahl, Anders Pettersson, Defeng Lang
The sensor is shown in Fig. 1. The trace width and separation are both 0.2 mm. The active area of the sensor is approximately 15 × 40 mm with about 1.6 cm2 each of zinc and ENIG. Zinc, which is significantly more electronegative than gold, is thus used for the cathode and gold is used for the anode. The metal that is lower in the galvanic series in the applied conditions will always tend to oxidize first, given that there is an electrolyte or conducting path between them. Gold is slightly electropositive, which makes it a good metal for the anode. The galvanic sensor concept requires corrosion to occur for a current to be measured due to two different metals being present. For this experiment, zinc was used simply due to its ease of electroplating and lack of sputter deposition instruments, but it is important to note that it might not be suitable for every application. The trace width and separation are kept to the smallest values possible with the available manufacturing methods to maximize the surface interaction between the traces and the grease. As shown in the center of Fig. 1, the sensor has room for a temperature sensor. However, the temperature sensor is not installed on this board because it is not needed for this experiment, which was performed at room temperature. The size of the sensor board was chosen to be as small as possible while still providing a measurable current.