In general, aluminum corrosion refers to the chemical decay of aluminum molecules into oxides. As a result, this compromises the metal’s properties. For example, aluminum windows corrode, and their strength is significantly reduced. As the metal is eaten away, it can develop fractures and cracks. The severity of aluminum corrosion will depend on the metal surface and environment.
Pitting is the most common type of corrosion that affects custom aluminum extrusions and other aluminum materials. However, it can only occur where an electrolyte, such as water or moisture, is present, which contains dissolved salts or chlorides. Small pits begin to appear on the surface of the metal.
Pitting is primarily an aesthetic problem, but it is unpredictable and could lead to performance failure when surface appearance is critical. These tips will help you avoid pitting in your aluminum components.
Three tips on how to avoid pitting corrosion
- Painting, anodizing, or any surface treatment that forms a coating on the aluminum surface will protect the surface from a pitting attack. In applications where you want to preserve the aluminum look and still have a surface resistant to pitting, a clear coat or thin anodic coating would be suitable for surface treatment.
- Anodizing involves forming a natural oxide layer on the metal’s surface. While it may help in making the metal less susceptible to corrosion, the resulting layers are oftentimes thin. On the other hand, powder coating is a heavily preferred coating option that involves using a mixture of resin and pigment. It is applied through a spray gun with a negative electrostatic charge to the powder. As a result, the powder remains fused to the aluminum’s surface after being cured inside the curing oven. This coating is immensely corrosion-resistant, thick, cost-effective, offers a wide array of colors and textures, and is resistant to color fading. If you’re concerned about aluminum corrosion, it would be best to go for powder coating.
- Pitting on aluminum profiles or sheet surfaces may also be kept to a minimum by regular cleaning of the surface. For cleaning, use mild alkaline or acidic detergents.
- Another common way to protect from corrosion is to store it in a climate-controlled environment. Corrosion is the result of environmental elements that trigger a chemical reaction in aluminum. It can occur if the aluminum is exposed to a very damp environment where salt is present. If possible, store your aluminum parts and products in a climate-controlled environment where they are not exposed to moisture, salt, air pollutants, and other natural factors.
Four suggestions to reduce corrosion in construction
- Avoid angles and pockets in which water can accumulate. Instead, use a shape that promotes draining.
- The risk of dirt build-up is reduced with increased radius in corners.
- Stagnant water is avoided by suitably inclining the profile and/or providing drainage holes (recommended minimum 8 mm). This is to avoid capillary forces to preserve water in the construction.
- The ventilation of “closed” constructions reduces the risk of condensation.
Works Cited: How to prevent pitting corrosion in your aluminium designs 3 Ways to Protect Aluminum from Corrosion