There are several methods of surface treatment of aluminum alloy

Sandblasting, the main role is to clean the surface, sandblasting before painting (painting or spraying) can increase the surface roughness, and has a certain contribution to the improvement of adhesion, but the contribution is limited, it is not as good as chemical coating before treatment.
Passivation is the method of transforming the metal surface into a state that is not easy to be oxidized, and delaying the corrosion rate of the metal.
Coloring: There are two main processes for aluminum coloring: one is aluminum oxidation coloring process, and the other is aluminum electrophoresis coloring process. Various colors are formed on the oxide film to meet certain requirements, such as black for optical instrument parts and gold for commemorative MEDALS.
Conductive oxidation (chromate conversion film) - used in situations where both protection and conductivity are required.
Chemical polishing Chemical polishing is a chemical processing method that uses the selective self-dissolution of aluminum and aluminum alloys in acidic or alkaline electrolyte solutions to smooth and polish the surface of the year to reduce its surface roughness and PH.
This polishing method has the advantages of simple equipment, no power supply, not limited by the shape size of the workpiece, high polishing speed and low processing cost. The purity of aluminum and aluminum alloy has a great impact on the quality of chemical polishing, the higher its purity, the better the polishing quality, and the worse it is.
Chemical oxidation: The oxide film is thin, the thickness is about 0.5 ~ 4 microns, and porous, soft, with good adsorption, can be used as the bottom layer of organic coating, but its wear resistance and corrosion resistance are not as good as anodic oxidation film;
The chemical oxidation process of aluminum and aluminum alloy can be divided into two categories according to the properties of its solution: alkaline oxidation method and acid oxidation method.
According to the properties of the film layer, it can be divided into: oxide film, phosphate film, chromate film, chroma-phosphate film.
Spraying: used for external protection and decoration of equipment, usually on the basis of oxidation. Aluminum parts should be pre-treated before coating in order to make the coating and the workpiece firmly combined, there are generally three methods: phosphating (phosphate method), chromium (no chromium chromium), chemical oxidation.
Electrochemical oxidation, aluminum and aluminum alloy chemical oxidation treatment equipment is simple, easy to operate, high production efficiency, does not consume electricity, a wide range of application, not limited by the size and shape of parts. The thickness of the oxide film is about 5 to 20 microns (the thickness of the hard anodic oxide film can reach 60 to 200 microns), has high hardness, good heat resistance and insulation, corrosion resistance is higher than that of the chemical oxide film, porous, and has good adsorption capacity.