Anodes can be manufactured from a number of different materials which is why understanding their respective properties and applications is of critical importance. It will allow you to get the right anode for your specific requirements. The most common metals that are used in the manufacture of anodes include zinc, aluminium and magnesium. In this blog, we’ll take a closer look at the properties of magnesium, how it works and the applications it is recognised for.
Magnesium has the symbol Mg. If you’re wondering where the name came from it was derived from the Greek word “Magnesia”, a district of Thessaly. The metal itself was first isolated by Sir Humphrey Davy in 1755.
It has the following properties:
Magnesium is shiny and silver in appearance, strong, sinks in water but is still relatively light in weight. Chemically, magnesium is oxidation resistant and this is because of its surface is covered with a thin layer of oxide which protects it from being vulnerability to air. This is why it is highly suitable for use in sacrificial anodes to limit the effects and susceptibility of other metal surfaces to corrosion.
How your magnesium anodes work
Magnesium anodes protect steel by a sacrificial electro-chemical action. Magnesium is electro-negative relative to steel. When a magnesium rod is connected by an electrical conductor to a steel tank which is then filled with water, a current will constantly flow through the water between the rod and any bare steel area on the wall. The circuit is completed through the tank back to the magnesium rod. This protective current is produced by the magnesium releasing ions, and this results in corrosion in the anodic area. This type of galvanic protection is called ‘sacrificial’; the magnesium rod (the anode) corrodes instead of the tank (the cathode). This principle of electrolytic corrosion control is called ‘Cathodic Protection’. Because cathodic surfaces cannot rust, the tank is protected.
The sacrificial magnesium anode equalises aggressive water action providing cathodic protection for the tank. The anode rod is a very important factor in tank life and should only be removed for inspection or draining. Replacement of the anode rod is recommended when consumption of weight loss is greater than 75%. With regular inspection and replacement of the anode rod, tank life can be greatly extended. The frequency of anode replacement will vary depending on the water conditions and usage. In most conditions, anode rods should last at least one year. If your magnesium anode rod does not last for one year, you may want to use an Aluminium Anode.
Magnesium anode applications
It is difficult to assign each type of anode a single use or application as they are a number of variables that must be considered in each use case. However, having a knowledge of the different applications will help ensure you never buy an anode that is not suited to your needs which can be equally as frustrating as buying clothes in a store only to find that they don’t fit when you get home. It’s always better to be safe, aware and knowledgeable than sorry.
Magnesium anodes are effective and affordable when it comes to battling corrosion. For over two decades, magnesium anodes have played a pivotal role in the protection of steel structures in salt and fresh water, including:
Get your magnesium anodes today
We have a vast range of magnesium anodes. If you think you might require one to resolve your corrosion or rust problem then get in touch with us today. Our team is on hand and keen to assist.
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