Aluminum corrodes in a dishwasher due to a combination of factors, mainly the harsh environment inside the dishwasher and the chemical reactions that occur with the dishwasher detergent. The dishwasher environment can be particularly aggressive towards certain metals, including aluminum, leading to corrosion over time. Here are the main reasons why aluminum corrodes in a dishwasher:
Detergents and chemicals: Dishwasher detergents often contain alkaline agents and abrasive chemicals to help remove tough stains and food residues. These chemicals can react with the surface of aluminum, leading to corrosion. Alkaline agents can create an alkaline environment that facilitates the dissolution of aluminum oxide, exposing the underlying metal to further corrosion.
High temperatures and humidity: Dishwashers use hot water and high-temperature drying cycles to clean and sanitize dishes. The combination of high temperatures and the presence of humidity can accelerate the corrosion process, especially if the protective oxide layer on the aluminum's surface is compromised.
Presence of other metals: In most modern dishwashers, various metals and alloys are used in the construction, such as stainless steel, brass, and copper. When different metals come into contact in the presence of water and detergents, they can create galvanic cells, leading to galvanic corrosion. In such cases, aluminum can act as the less noble metal, accelerating the corrosion process.
Pitting corrosion: Aluminum is susceptible to pitting corrosion, which involves the localized corrosion of small areas on the surface. Pitting corrosion can be exacerbated by the dishwasher's aggressive environment and can lead to the formation of small pits and holes on the aluminum surface.
Due to these factors, it is generally not recommended to put aluminum items in the dishwasher, especially if they are not specifically labeled as dishwasher-safe. To protect your aluminum items from corrosion:
Hand wash aluminum items: To preserve their appearance and integrity, hand wash aluminum items using a gentle dishwashing soap and a soft sponge or cloth.
Separate aluminum from other metals: Avoid putting aluminum items in direct contact with other metals in the dishwasher to minimize the risk of galvanic corrosion.
Use dishwasher-safe aluminum items: Some aluminum items are designed to be dishwasher-safe, with protective coatings or treatments to resist corrosion. Always check the manufacturer's guidelines before placing aluminum items in the dishwasher.
By following these precautions, you can help extend the life of your aluminum items and prevent unnecessary corrosion in the dishwasher.