The surface treatment of Changshu aluminum can be seen from the oxidation of sulfuric acid solution. In the solution area near the anode, the content of aluminum ions increases, oxygen precipitates and oxide film is formed, while the hydrogen precipitates on the cathode, and the formation of oxide film reflects that the two steps are carried out at the same time. That is, the electrochemical film-forming process and chemical dissolution process of the oxide film. Of course, only when the film-forming speed is greater than the film dissolution speed, the thickening and formation of the oxide film is possible. Because the resistance of the aluminum oxide film is very large, when its thickness reaches a certain limit, the resistance hinders the continuation of the anode reaction and the current cannot pass through. At this time, The film-forming rate is equal to zero and the dissolution process does not stop, so the thickness of the formed oxide film tends to be thinner.

The essence of the anodizing process of Changshu aluminum surface treatment is the discharge of H + and oh - and then the oxidation of aluminum by neoecological oxygen to form Al2O3. At the beginning of oxidation, a thin and fine oxide film (i.e. the non porous inner layer close to the metal surface) is quickly formed on the anode, and the resistance is also large. In the first few seconds, the voltage rises sharply, which leads to "breakdown" in the local thin part of the oxide film.

At the breakdown place of Changshu aluminum surface treatment, the dissolution of the film is accelerated, holes appear, and then extend, providing conditions for further thickening of the film, and hexagonal shapes are formed around the holes to form the outer layer of the oxide film.