This is due to its light weight, but also to its resistance to corrosion. When the alloy is exposed to water, a film of aluminum oxide forms quickly on the surface.
The hard oxide layer is quite resistant to further corrosion and protects the underlying metal. These three metals contain little or no iron, and so do not rust, but they can react with oxygen. Copper oxidizes over time to form a green patina, which actually protects the metal from further corrosion.
Bronze is a mixture of copper and tin, along with small amounts of other elements, and is naturally much more resistant to corrosion than copper. Brass is an alloy of copper, zinc, and other elements, which also resists corrosion.
Galvanized steel takes a long time to rust, but it will eventually rust. This type is carbon steel that has been galvanized, or coated, with a thin layer of zinc. The zinc acts as a barrier preventing oxygen and water from reaching the steel, so that it is corrosion protected.
Even if the zinc coating is scratched off, it continues to protect nearby areas of the underlying steel through cathodic protection, as well as by forming a protective coating of zinc oxide.
Like aluminum , zinc is highly reactive to oxygen in the presence of moisture, and the coating prevents the iron in the steel from further oxidation. That seems a small price to pay for up to 1, years of corrosion-resistant performance, but the initial cash price of these metals might cause second thoughts.
For those still timid about picking materials, the best bet is to meet with a roll former and get the longer version. An experienced roll forming expert will also be able to go over any bending-specific worries when using certain metals.
A roll forming expert can also help guide you in the right direction for designing a great roll formed part. To help get you started, download our free e-book below:. Editor's note: This article was originally published in November , and has recently been updated. Topics: Materials , Architectural Mouldings. These sleek, modern products are now popular in not only commercial architecture, but in residential applications as well. Choosing the right aesthetic for your architectural project is more complex than it may seem.
There are many metals to choose from, and many types of finishes available. Each finish provides its own unique aesthetic, and the finished effect will shift depending on the richness, lighting, and[ For free education on materials, applications and more for both OEM and architectural roll forming -- delivered right to your email.
Breaking Down Corrosion-Resistant Metals Some metals and metal alloys are more corrosion-resistant than others, of course. Somewhat Resistant: Galvanized Steel A coated layer of zinc standing between the elements and the interior gives galvanized steel a measure of corrosion resistance. Mildly Resistant: Aluminum A kind of miracle metal, aluminum has the power to create its own corrosion-resistant coating. Anodizing aluminum is a process that: Hastens the formation of the resistant coating Strengthens the metal Creates a polished finish Within the aluminum grades, H32 stands out for its corrosion resistance.
Strongly Resistant: Stainless Steel There are lots of stainless steel grades. For exterior use, the most commonly specified grades are: stainless steel stainless steel stainless steel Grade stainless is the one to use in harsh marine environments.
Galvanized steel is technically a coated material, but it is worth mentioning here. Galvanized steel is a carbon steel that would most likely rust if it did not have one or more layers of zinc applied to it.
The zinc layer acts as a sacrificial metal for the steel. This means that the zinc layer will combine with the oxygen more readily than the iron in the steel will.
This creates a zinc oxide layer that prevents the formation of iron oxide, thus eliminating the possibility of rust forming. However, if the zinc coating is damaged, or if the galvanized steel is placed in extreme environments, the zinc coating may be rendered ineffective and the steel will rust. The formation of white rust does not necessarily damage the material or the zinc coating.
Copper , brass , and bronze do not rust for the same reason as aluminum. All three have a negligible amount of iron in them. Therefore no iron oxide, or rust, can form. However, copper can form a blue-green patina on its surface when exposed to oxygen over time. They have their own forms of corrosion, such as pitting that can occur in stainless steel or the blue-green tarnish found on oxidized copper.
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