What are the surface treatment methods for aluminum alloy parts?
1. Sandblasting is mainly used for surface cleaning of aluminum alloy parts. Sandblasting (paint or plastic) before painting can increase surface roughness and help improve adhesion, but has a limited effect. Not as good as chemical paint pretreatment.
2. Passivation is a method of transforming the metal surface into a state that is not easily oxidized and delaying the corrosion rate of the metal
3. Coloring: The coloring of aluminum alloy parts mainly includes two processes: aluminum oxidation coloring and aluminum electrophoresis coloring. Various colors are formed on the oxide film: for example, the optical instrument parts are black, and the commemorative medals are golden yellow to meet certain usage requirements.
4. Chemical polishing is a chemical processing method in which aluminum and aluminum alloys are selectively autolyzed in acidic or alkaline electrolytes to smooth and polish the surface of the year to reduce surface roughness and PH value. This polishing method has the advantages of simple equipment, no power supply, no limitation of part size, fast polishing speed, and low processing cost. The factors that have a great influence on the quality of chemical polishing include the purity of aluminum and aluminum alloys. The better the polishing quality is, the higher the purity is required, and vice versa.
5. Chemical oxidation: The oxide film is thin, about 0.54 microns thick, porous, smooth, and has good adsorption performance. It can be used as a base coat for organic coatings, but its abrasion and corrosion resistance are not. As good as the anode oxide film: The chemical oxidation process of aluminum and aluminum alloys can be divided into two categories according to the nature of the solution: alkaline oxidation and acid oxidation. According to the nature of the film, it can be divided into oxide film, phosphate film, chromate film, and chromate-phosphate film.
6. Spraying: Generally, oxidation is the main method, and it is used for the external protection and decoration of equipment. The aluminum parts must be pretreated before spraying so that the wall plate and the workpiece can firmly adhere together. Generally, there are three methods: phosphating (phosphate method), chrome plating (chromium-free chrome plating), and chemical oxidation.
7. Electrochemical oxidation and chemical oxidation treatment of aluminum and aluminum alloys are easy to operate, simple in equipment, high in production efficiency, widely used, and are not limited by the size and shape of the workpiece. The thickness of the oxide film is about 5-20 microns (hard anodized film thickness can reach 60-200 microns). It has high toughness, good heat resistance, and insulation, and its corrosion resistance is higher than that of chemicals. Porous oxide film with good adsorption capacity.