Galvanic Corrosion

Abstract

Corrosion can be defined as the deteoration of metals and alloys due to a interaction with their environments. There are several types of corrosion such as general corrosion , galvanic corrosion, pitting corrosion, intergranular corrosion, atmospheric corrosion. Galvanic corrosion, also known as bimetallic corrosion, is an electrochemical process which occurs when two different metals are immersed in electrolytic solution due the difference of electrode potentials of dissimilar metals. One of the metals is anode and other is cathode in the couple. Metals and alloys have different electrode potentials. The less noble metal is anode tends to corrode faster than cathode. The electrolyte acts as a conductive noble metal is protected. Several factors affect galvanic corrosion rate, such as potential difference between metals, cathode efficiency, surface areas of the connected metals , electric resistance difference of the connected metals and electrolyte. When a metal is in contact with a metal which is close in galvanic series. For example, zinc aluminum couple shows 300mV potential in sodium chloride solution whereas zinc copper couple indicates 700 mV. The greater the potential difference, the greater the power to conduct galvanic corrosion. 

Keywords

• Alkaline,Media

References

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