Protecting steel from oxidation is a must for many projects. While applying a zinc coating to (known as galvanising) steel is one common method to prevent corrosion, another material type, known as Galvalume (or Aluzinc, or Zincalume), may also be a suitable option. But what is Galvalume?
What is Galvalume?
Galvalume is a coating consisting of zinc, aluminium and silicon that is used to protect a metal (primarily steel) from oxidation. It is similar to galvanising in that it is a sacrificial metal coating which protects the base metal.
What is Galvalume Used For?
Galvalume is primarily used to protect iron-based alloys that are prone to rust. Galvalume-coated steel is better able to resist oxidation than plain carbon steel because the zinc and aluminium protect the underlying steel from the environment. The zinc also will more readily oxidize than the steel it contacts. This is similar to galvanised steel.
What is the Difference Between Galvanising and Galvalume?
The main difference between galvanising and Galvalume is that galvalume is a combination of zinc, aluminium, and silicon, while galvanising is 100% zinc. The makeup of the three elements in a Galvalume coating is just over 50% aluminium, just under 50% zinc, with trace amounts of silicon.
An advantage that Galvalume has over normal galvanised material is that it has enhanced protection abilities. Over time, Galvalume tends to perform better than galvanised steel, especially when exposed to water or other liquids that can speed up the oxidation process. Even after a few decades, Galvalume-coated steel will be less likely to rust than normal galvanised steel.
Galvalume is also considered more aesthetically pleasing than hot-dipped galvanised materials.
Galvalume is applied to a material using the hot-dipping process. Therefore, a Galvalume coating has similar thicknesses to that of hot-dipped galvanised material. The thickness for the hot-dipping process is around 1 mil thick. The thickness can range somewhat depending on the coating specification. If the coating thicknesses of a Galvalume-coated steel and a galvanised steel are equal, the Galvalume steel will generally outlast the galvanised one, depending on the environment.
What Type of Metal Is Galvalume?
Galvalume coating is most commonly applied to carbon steel. However, most materials that can be galvanised can also be coated with Galvalume. Some additional metal types include:
When is Galvalume Used?
One of the most popular applications of Galvalume steel is for outdoor metal paneling and roofing. Galvalume is used because it has superior resistance to corrosion in outdoor environments than standard galvanised steel. It is able to resist corrosion when exposed to snow, ice, and rain.
When Should Galvalume Not Be Used?
Galvalume should not be used in alkaline environments. The aluminium in Galvalume does not hold up well to that type of environment, so galvanised steel may be a better choice in that instance. Also, Galvalume does not do well if it is damaged. If the panel will be subject to scratches and indentation, then galvanised steel may be better suited as the material for the application. Even fastener installation may be enough to damage the Galvalume coating.
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