A graphite anode is a conductive part of an electrical system or medium. Graphite anodes are commonly used in cathodic protection (CP) systems. Used to protect the structural integrity of buildings and metal structures, especially those that are underwater or underground, cathodic protection systems are systems that use electric current to prevent corrosion in metal structures. Within a CP system, the graphic anode is the part that outputs the protective current.
Types of cathodic protection systems that employ a graphite anode to avoid corrosion in metal structures include galvanic and impressed current cathodic protection systems (ICCP). In addition to protecting metal structures like bridges, buildings and offshore oil rigs from corrosion damage, cathodic protection is also used to prevent corrosion on metal parts on ships, most frequently the hull. Galvanic protection relies on the graphite anode having a more negative charge than the protected metal to attract the corrosion to a more corrosive surface. Cathodic protection systems using impressed current technology use direct current (DC), often converted from AC power, to supply current to a more powerful graphite anode system that reduces corrosion in a larger metal structure by attracting the corrosion to a more corrosive material. ICCP technology is more powerful than galvanic protection systems, and is generally used for ships and metal pipelines.
Most of the time, cathodic protection technology is used in addition to other corrosion protection methods, like galvanization, a process in which the protected metal is coated in a layer of zinc to guard it from corrosion. With respect to conductivity, graphite is one of the most effective materials used for anodes in a cathodic protection system. Other types of material used for cathodic protection anodes include zinc and aluminum.
The cathode is the connecting point through which the current escapes the powered device and returns to the electric medium. Most people are familiar with anodes and cathodes from their appearance on the common batteries used in everyday electronics. The anode is the negative end of the battery. Graphite can be recognized as the soft gray material that makes a pencil write.
An anode is a type of electrode. Electrodes are the conductive connecting points where current either enters or leaves an electric medium, like a battery. An anode is the end where the current leaves the electric medium and flows into a device, like a light bulb. A graphite anode is related to a graphite cathode, another kind of graphite electrode. Graphite cathodes have a different use than cathodic anodes; they are often employed to conduct protein testing in molecular biology fields.