Corrosion exists everywhere. It may by detrimental or beneficial. Corrosion can result in catastrophic failures or a slow deterioration. You may not realize but corrosion is not always a bad result. Portable electronics, such as mp3 players and flashlights, work because of corrosion, which produces electricity in the device’s batteries. Corrosion can occur in air, water or soil. However, one critical factor must always be present for corrosion to occur: an electrolyte. An electrolyte must be present so that electrical circuit can be closed. When two metals are placed in the same electrolyte, metal ions will pass from one metal to the other. The metal that extrudes the ions is called the anode, while the metal that receives the ions is called the cathode. For example, a battery is comprised of an anode and a cathode in an electrolyte. The most common battery used in portable electronics is a Lithium [Li-ion] battery. Lithium is the electrolyte that transports the metal ion, cobalt [Co], and closes the electrical circuit that produces electricity. During recharging, the cobalt ion is reduced to a lower energy state that restores potential energy [electricity] back to the battery. The battery is a simple but useful form of corrosion.

The fundamentals of corrosion are based in electrochemistry, which is the study of chemistry on the atomic scale. Using the basics of electrochemistry, we can force corrosion to occur. We place a metal in an electrolyte, such as salt water, and apply a current to the metal. The voltage is slowly increased on the metal specimen until corrosion starts. However, there are times when corrosion will not initiate. For example, noble metals, such as platinum or gold, would not corrode in salt water. However, a metal like carbon steel would corrode. Conducting this simple experiment is an example of an electrochemical corrosion test.