The corrosion resistance of aluminum alloy products is achieved through a variety of mechanisms. The following is a detailed description of this process:
1. Formation of natural oxide film
In the natural environment, aluminum alloys will spontaneously form a dense aluminum oxide (Al₂O₃) protective film on their surface. This film is the main reason for the atmospheric corrosion resistance of aluminum alloys. The aluminum oxide film has a high degree of chemical stability and density, which can effectively isolate the direct contact between the aluminum matrix and the external environment, thereby preventing or slowing down the occurrence of corrosion. Although this naturally formed oxide film has a certain degree of corrosion resistance, its thickness and density are often limited, and it is difficult to meet high-demand application scenarios.
2. Artificial surface treatment
In order to improve the corrosion resistance of aluminum alloy products, artificial surface treatment methods are usually used to form a more solid and dense protective film on the surface of aluminum alloys. These methods include anodizing, electrophoretic coating, spraying, etc.
Anodizing:
Anodizing is an electrochemical treatment process that forms a thick aluminum oxide film on the surface of aluminum alloys by placing aluminum alloys as anodes in electrolytes and applying voltage for electrolysis. This film has a double-layer structure, consisting of a dense barrier layer and a porous layer with a columnar structure, which can significantly improve the corrosion resistance of aluminum alloys. During the anodizing process, the thickness and quality of the oxide film can be adjusted by controlling the process parameters to meet the needs of different application scenarios.
Electrophoretic coating:
Electrophoretic coating is another common surface treatment method for aluminum alloys. This method uses the principle of electrophoresis to make the paint particles migrate to the surface of the aluminum alloy under the action of an electric field and deposit to form a coating. The coating formed by electrophoretic coating has the characteristics of uniformity, density, and strong adhesion, which can significantly improve the corrosion resistance and decorativeness of aluminum alloys.
Spraying:
Spraying is a method of spraying the paint into mist droplets through a spray gun or a disc atomizer and evenly coating it on the surface of the aluminum alloy. The spray coating can be selected and adjusted as needed to meet different corrosion resistance and decorative requirements. Common spray coatings include fluorocarbon paint, polyester paint, etc.
3. Alloying treatment
In addition to surface treatment, alloying treatment is also an effective means to improve the corrosion resistance of aluminum alloys. By adding appropriate amounts of alloying elements (such as copper, magnesium, zinc, etc.) to aluminum alloys, alloys with higher corrosion resistance can be formed. These alloying elements can form stable compounds or solid solutions with the aluminum matrix, thereby improving the corrosion resistance of aluminum alloys. At the same time, alloying treatment can also adjust the microstructure and mechanical properties of aluminum alloys to make them more suitable for specific application scenarios.
4. Environmental control
In addition to the above methods, environmental control is also one of the important measures to improve the corrosion resistance of aluminum alloys. When using aluminum alloy products, try to avoid exposing them to humid, corrosive gases and chemicals. By controlling environmental conditions, the contact opportunities between aluminum alloys and corrosive media can be reduced, thereby delaying or preventing the occurrence of corrosion. For example, aluminum alloy products used in marine environments should take special anti-corrosion measures, such as coating anti-corrosion coatings or cathodic protection.
In summary, the corrosion resistance of aluminum alloy products is achieved through a variety of mechanisms such as the formation of natural oxide film, artificial surface treatment, alloying treatment and environmental control. These measures can be selected and optimized according to specific application scenarios and needs to achieve the best corrosion resistance.
