Surface Treatment Of Aluminum Die Casting For Automobile

　　Aluminum die casting for automobile is a precision casting method that uses high pressure to force metal melt into a metal mold with complex shapes. It is a precision casting method.

　　There are many post-processing techniques for aluminum alloy products, mainly in the following categories:

　　1. Sandblasting is mainly used for surface cleaning. Sandblasting before painting (painting or plastic spraying) can increase the surface roughness, which has a certain contribution to the improvement of adhesion, but the contribution is limited, and it is not as good as chemical coating pretreatment.

　　2. Passivation is a method of converting the metal surface into a state that is not easily oxidized and delaying the corrosion rate of the metal.

　　3. Coloring: There are two main processes for coloring aluminum: one is the aluminum oxidation coloring process, and the other is the aluminum electrophoresis coloring process, which forms various colors on the oxide film to meet certain use requirements, such as Optical instrument parts are often black, and medals are gold.

　　Conductive Oxidation (Chromate Conversion Coating) - Used where both protection and conductivity are required.

　　4. 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 level and polish the surface to reduce its surface roughness and PH.

　　This polishing method has the advantages of simple equipment, no power supply, no restrictions on the size of the workpiece, high polishing speed, and low processing cost. The purity of aluminum and aluminum alloys has a great influence on the quality of chemical polishing. The higher the purity, the better the polishing quality, and vice versa.

　　5. Chemical oxidation: The oxide film is thin, with a thickness of about 0.5 to 4 microns, and is porous, soft, and has good adsorption properties. It can be used as the bottom layer of organic coatings, but its wear resistance and corrosion resistance are not as good as anodes. Oxide film;

　　The process of chemical oxidation of aluminum and aluminum alloys can be divided into two categories: alkaline oxidation and acid oxidation according to their solution properties.

　　According to the film properties, it can be divided into oxide film, phosphate film, chromate film, and chromate-phosphate film.

　　6. Spraying: used for external protection and decoration of equipment, usually based on oxidation. Aluminum parts should be pre-treated before coating to make the coating and workpiece firmly bonded. Generally, there are three methods: phosphating (phosphate method), chromatin (chromium-free chromatin), and chemical oxidation.

　　7. Electrochemical oxidation, chemical oxidation treatment equipment for aluminum and aluminum alloys is simple, easy to operate, has high production efficiency, does not consume electricity, has a wide range of applications, and is 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-anodized film can reach 60 to 200 microns). It has high hardness, good heat resistance, and insulation, and has higher corrosion resistance than chemical oxide films. adsorption capacity.