What Does Aluminum Corrosion Mean?
Aluminum corrosion is defined as the electrochemical and other reactions of the metallic substance with its environment, causing the deterioration and degradation of the aluminum material as well as its essential properties.
Corrosionpedia Explains Aluminum Corrosion
The study of aluminum corrosion is very important because this metal, along with its alloys, is widely used for critical applications like power cables and aircraft. Aluminum is also used as a sacrificial anode, preventing the corrosion of other metals through a cathodic protection system. Reducing material deterioration due to aluminum corrosion will extend the life of critical equipment and reduce the risk of danger to life and property.
Aluminum and its alloys are subjected to corrosion in the presence of moisture and oxygen. However, the resulting thin film formed on the surface of the aluminum structures and components acts as a protective barrier between the parent metal and the environment, thus preventing further deterioration of the substrate or parent metal. Initially the aluminum surface remains reactive, but it becomes passive due to oxide film on the surface after the electrochemical reaction. Hence, aluminum is considered to be corrosion resistant. Because of this property aluminum is used in outdoor applications like overhead power cables and roof sheets.
The oxide film on the aluminum surface becomes highly unstable in the presence of a reactive liquid acting as an electrolyte with an extreme pH value, either lower than four or higher than nine. Saltwater is an example of such an electrolyte. When an aluminum surface is in electrical contact with a metal of different electron potential and dipped in an electrolyte, the flow of electricity between the two metals causes galvanic corrosion. If the aluminum conductor is connected with steel nut bolts, and there is a saltwater ingress in the crevice, then galvanic corrosion causes deterioration of the aluminum.