The purpose of chromate treatment on aluminum before powder coating is to enhance its corrosion resistance and adhesion. Chromate treatment involves immersing the aluminum in a solution containing chromate salts to form a protective layer of chromate compounds on the surface. The chromate treatment can be carried out through the following steps: 1. Surface cleaning of aluminum: Use alkaline cleaning agents or descaling agents to remove oil, oxide, and other impurities from the surface of the aluminum. 2. Acid washing of aluminum surface: Immerse the aluminum in an acidic solution using acid detergents to remove the oxide layer and other impurities from the surface. 3. Chromate treatment: Immerse the aluminum in a solution containing chromate salts to react with the aluminum surface and form a layer of chromate compound protective layer. The time and temperature of chromate treatment can be adjusted according to specific conditions. 4. Rinse: After removing the aluminum from the chromate solution, thoroughly rinse the surface of the aluminum with clean water to remove residual chemicals. 5. Drying: Place the aluminum in a well-ventilated area to air dry or use drying equipment to accelerate the drying process. After chromate treatment, a dense layer of chromate compound protective layer will form on the surface of the aluminum, effectively improving its corrosion resistance and adhesion, providing a better foundation for the powder coating process.