1. The higher the purity, the better the corrosion resistance. It is well known that pure aluminum reacts with oxygen in the air, and a very thin and dense natural oxide film is produced on the surface of aluminum, which is faster than other metal oxide films. It is thicker, thus preventing the corrosion of harmful gases and moisture in the air and protecting it;

2. Although the corrosion resistance of pure aluminum is good, but the mechanical strength is poor, this restricts the application of aluminum to a certain extent. Therefore, people add appropriate amounts of other metals such as magnesium, copper, zinc, etc. to aluminum to make various types. The high mechanical strength of the aluminum alloy and the aluminum alloy greatly improves the mechanical strength of the aluminum, and the application range is greatly expanded. Although the aluminum alloy has high mechanical strength, the corrosion resistance is inferior to that of pure aluminum, so it may be corroded by oxidation. This requires the application of powder coating to protect the aluminum alloy profile. The aluminum alloy has been widely used in doors, windows and curtain walls of buildings for many years due to its small specific gravity, easy processing and high mechanical strength.