The sacrificial anodizing film of aluminum alloy is a porous film. Whether it is colored or not, it must be sealed before it is put into use to improve its corrosion resistance and weather resistance. The treatment methods include high-temperature hydration reaction sealing and inorganic salt sealing.
(1) High-temperature water sealing
This method uses the hydration reaction of aluminum oxide film and water to convert the amorphous film into a hydrated crystalline film: the hydration reaction can be carried out at room temperature and high temperature, but at high temperature, especially at boiling point, the generated hydrated crystalline film is a very stable and irreversible crystalline film. Therefore, the commonly used sealing treatment of aluminum oxide film is boiling water method or steam method.
(2) Inorganic salt sealing
The inorganic salt method can improve the fastness of coloring dyes, so it is commonly used in chemical coloring methods.
① Acetate method
② Silicate method