cathodic protection

Cathodic protection is an important technique used to prevent the corrosion of a metallic surface by creating an electrode of an electrochemical cell at a high potential. An electrochemical cell is simply a circuit made up of two or more metals with an electrolyte that can be, usually, a salt or sulfuric acid. A very simple way of protecting the metal from being corroded is connected to the metal to be protected, via a sacrificial electrode, to easily corroded metal at a higher potential. When the circuit is turned on, or when the potential difference across the sacrificial electrode is equalized, the metal in question will develop an electrical charge, which it quickly deposits upon contact with the sacrificial electrode. When this process is repeated many times, the accumulated electrostatic charge over time will build enough electrostatic energy to cause the formation of what is called an arc or spark, in the area where the electrode was connected.

Because this potential electrical charge is generated at a high potential, there is always a risk that it may be released without incident. In order to prevent the cathodic charge from escaping to the environment, special chemical coatings have been applied to metal surfaces. These coatings serve to protect the metal and make it much harder for the cathodic current to flow from the protected surface into the surrounding environment. There are several different cathodic protection materials in use today, including some varieties of lead sulfate, a commonly used chemical coating that has good cathodic protection properties. The material that is most often applied to metal surfaces in the auto industry is polyester mesh, which provides excellent mechanical protection against corrosion.

 

cathodic protection systems are not limited to car and motorcycle applications. In fact, they are an important part of protecting various other non ferrous metals used in the manufacture of household safety products and electronics. Metal abatement processes, including sanding and blasting, as well as various other chemical treatments can sometimes be performed without the use of a protective coating. Some of these processes have the potential to produce extremely hazardous fumes, so protection is particularly important in these instances. Some of the other chemicals that may sometimes be used in the process of metal abatement include bromine and sulfur dioxide.