Nickel anodes are used in one type of the nickel-plating process called electroplating. These anodes are usually pure metal molded in the shape of a pellet or small coin-like disk. Nickel anodes can be used to plate nickel onto plastic or other metals. When plating an object with nickel, the nickel anode gets used up as the plating moves onto the base material. In electroplating, the base material that receives the plating is often called the substrate.
Electroplating uses an electrical current to make the nickel stick to the material to be plated. The anode is the positive electrode and the object that will be plated is the negative electrode. All of the nickel taken from the nickel anode is deposited onto the object targeted for plating. The thicker the layer of nickel on the intended object, the more nickel anode material is used during the plating process. Another method, electroless nickel plating, uses a chemical reaction to coat the substrate in nickel.
Contrary to its common name, the nickel, the metal content of the American five-cent coin has changed over time, often due to wartime metal shortages. Metals other than nickel that have been included in the nickel over time include silver, copper and steel. Modern American nickels are not plated in nickel; rather, they are made of a mixture of nickel and copper.
Other types of anodes include anodes used in batteries and anodes used to prevent metal corrosion, but a nickel anode is rarely used in these applications. In a battery, the anode is the end from which the circuit current flows into the powered device. When current flows through the device and back into the battery, it flows back in through the cathode end. The anode end is the negative end and the cathode is the positive end of the battery. Common types of anodes used in batteries include lithium and silicon anodes.
Rarely, an anode of nickel mixed with aluminum is used to prevent corrosion in metal structures. When a nickel anode is used to prevent metal corrosion, the process is called cathodic protection. In cathodic protection, the metal that is being protected from corrosion acts as the cathode. When an anode is made for cathodic protection, it is called a sacrificial anode.
A sacrificial anode is made of an easily corroded metal. Use of the sacrificial anode prevents corrosion by attracting the particles that would normally cause corrosion. Common types of metals used in sacrificial anodes include aluminum, zinc, and magnesium.