The Science of Steel Protection: Hot-Dipped Galvanization Explained


Galvanization is the process that protects steel, iron, and other metals from corrosion by applying a thin layer of molten zinc. This preventative coating protects the metal from rusting, even when exposed to the harshest environments. Over time, this process has become the most effective way to extend the lifespan of steel products, and at Armco Superlite, we have mastered this procedure.


Today, we will discuss the science behind hot-dipped galvanizing and how our steel structures last longer, making us one of the leading suppliers of galvanized steel throughout Africa.


Galvanization, Electrochemistry, and Galvanic Corrosion



The science behind galvanization is based on the principles of electrochemistry. Electrochemistry is the study of the chemical reactions that occur between types of material when they make contact with one another.


Although there is much debate about when galvanization was invented, there is evidence that zinc was applied to copper to create a brass alloy as far back as the 10th century B.C. But it is generally recognised by the Galvanizers Association of Australia that in 1836, the French chemist Stanislas Sorrel presented thoughts describing that when covering zinc over steel through the hot-dip process, the resultant metal would last for decades. This has since been proven true. Galvanized metal has been known to last over 100 years.


Allow us to explain. When the two metals are in contact with each other and are also in contact with an electrolyte, such as water or soil, a galvanic cell is created. This is when one metal acts as the anode and the other metal acts as the cathode. The anode is the metal that is corroded – or is the sacrificial metal – and the cathode is the metal that is protected from corrosion.


Zinc is more chemically reactive than steel. As a result, zinc ions are more likely to be lost in the electrolyte than iron ions. The loss of the zinc ions creates a positive charge on the zinc coating and the gain of electrons creates a negative charge on the steel.


The difference in electrical potential between the zinc coating and the steel creates an electrical current. The current flows from the zinc coating to the steel. It is this electrical current that drives the corrosion of the zinc film. That said, the zinc coating is sacrificial, which means that it will corrode itself to protect the steel.


What is Galvanic Corrosion?


As discussed above, when two dissimilar metals are in contact and submerged in an electrolyte, a phenomenon known as galvanic corrosion – also known as bimetallic corrosion – occurs. In this process, one metal remains protected, while the other undergoes accelerated corrosion. The rate of corrosion is significantly higher than when the protected metal is isolated.


Get Yourself Armed with Armco


Here at Armco Superlite, we pride ourselves in our superior-quality galvanized products. With two separate galvanizing stations situated in Isando and Randfontein, we can process steel of up to 13m in length and process approximately 2800 tonnes a month collectively.


We are listed in accordance with the BSI ISO 9001:2015 quality scheme, which offers you complete peace of mind when dealing with us. Additionally, we hold the SATAS mark of Hot-Dipped Galvanizing and everything galvanized at our premises is in accordance with the SANS 121/ISO 1461 specifications, again proving the quality of our products. Every item that leaves our premises is personally inspected to ensure our high-quality standards are maintained at all times.


Our galvanized products are used across a broad spectrum of industries for many applications, boasting a varied community of satisfied customers. Our products include culverts and underground tunnels in the mining, road safety, and construction industries amongst a host of others. Regardless of why you need galvanization, we can accommodate you, regardless of the size of your business.


So, why not consider arming yourself right, with Armco Superlite? Contact us for a consultation today.