Even aluminum that has not been treated has a very good amount of corrosion resistance in most environments and situations. The reason for this is that aluminum, as a material, forms a very thin but extremely effective oxide layer that works to prevent additional oxidation. This is why aluminum is such a quality, durable metal. The aluminum oxide, as the alloy is called, is impermeable and it sticks very strongly to the parent metal. This is unique to aluminum and aluminum oxide, as other metals that form oxide layers do not adhere as strongly. If the layer is damaged mechanically, the oxide layer of aluminum will repair itself immediately, returning to its protective form.
Two Types of Corrosion
There are two primary types of corrosion that are the most common. This includes galvanic corrosion and crevice corrosion. Galvanic corrosion can occur when there is metallic contact and an “electrolytic bridge” between two different metals. The lesser metal becomes the anode in the situation and corrodes, while the better metal becomes the cathode and becomes protected, creating a corrosion resistance.
Ironically, when combined with other types of metal, aluminum is usually the lesser metal, making it more susceptible to galvanic corrosion despite its normal corrosion resistance. This type of corrosion will not occur in a dry indoor location and there is a reduced risk of corrosion in rural areas. However, in areas where there are high levels of chlorides, such as land areas that border the ocean, other metals such as copper, stainless steel and carbon steel can cause aluminum to become subject to galvanic corrosion.
Another type of corrosion, known as stress corrosion, will often lead to the formation of cracks, which makes it a special type of corrosion. It is seen most often in high-strength alloys that have been subjected to tensile stress for a prolonged period of time while in the presence of a corrosive medium. However, this type of corrosion does not typically occur in aluminum oxide alloys due to its high level of corrosion resistance.
The second most common type of corrosion which can affect aluminum is crevice corrosion. This type of corrosion can occur in narrow crevices that are filled with liquid. However, the likelihood of this type of corrosion from happening in custom aluminum extrusions is very small. However, this type of corrosion has been seen in marine environments and on vehicle exteriors, particularly during transportation and storage. If water is allowed to collect in the crevices, even of custom aluminum extrusions, it can lead to superficial corrosion.
Water sources can be condensation, rain or other deposits of liquid that get pulled in between the different metal surfaces. If a cold material is taken into a warm place, condensation can form, allowing water to pool. Changes in temperature from daytime to night time can also create a pool of condensation. This occurs when aluminum gets stored outdoors under a tarp that provides a tight seal. If this action can be prevented, this quality durable metal will succeed with its natural corrosion resistance and remain undamaged.
Other Benefits of Aluminum Products
In addition to providing corrosion resistance, there are other benefits of aluminum products that make so many clients choose to use custom aluminum extrusions for their projects. Aluminum is a quality durable metal that costs less than other metals to extrude, fabricate and finish, but it is also a versatile metal that can be easily and quickly shaped through the custom aluminum extrusion process to create an endless variety of shapes and sizes.
Silver City Aluminum specializes in creating custom aluminum extrusions. In addition to providing quality durable metal products for our clients, we also work very hard to provide additional services, such as fabrication and finishing, establishing a truly one-stop-shop for our clients. To find out more about Silver City Aluminum and our capabilities for creating custom aluminum extrusions, either call or stop by our offices in Taunton, Massachusetts.
Ask about our industry solutions, which include custom aluminum extrusions for doors and windows, lighting and marine industry. We also have standard extrusions, special services and applications available. Give Silver City Aluminum a call and learn more about all of the services and options available to our loyal customers.