Surface treatment of aluminum processing
Surface treatment:
The surface treatment of aluminum alloy parts is divided into pre-treatment and post-treatment. The pre-treatment is to remove surface oxide skin and oil, increase post-treatment adhesion and improve the appearance effect. The most commonly used surface treatment of aluminum alloy parts are shot blasting, sandblasting and phosphating, and post-treatment is generally used for spraying, oxidation, electroplating and electrophoresis.
Choose from the cost aspect, processing methods shot blasting → blasting → phosphating → polishing, spraying → electrophoresis → oxidation → electroplating. Phosphating can only be sprayed, electrophoresed, can not do oxidation, plating.
Choose from decorative and anti-corrosion: The processing method is polishing → phosphating → sand blasting → shot blasting, oxidation → plating → spraying → electrophoresis.
1. Electrochemical method
This method is the use of an electrode reaction, the plating layer is formed on the workpiece surface. The main method is:
(1) Electroplating
In the electrolyte solution, the workpiece is the cathode. Under the action of the external current, the surface of the workpiece forms a plating layer, which is called electroplating. Coating all types of solid particles may be a metal, alloy, semiconductor, or containing, such as copper, nickel and so on.
(2) oxidation
In the electrolyte solution, the workpiece is an anode. Under the action of an external current, an oxide film layer is formed on the surface thereof, which is called anodization, and aluminum oxide film is formed on the surface of the aluminum alloy.
3, electrophoresis
The workpiece is used as an electrode, and a conductive water-soluble or water-emulsified coating is placed, and the workpiece and the other electrode in the coating constitute an electrolytic circuit. Under the action of the electric field, the coating solution has dissociated into charged resin ions, the cations move toward the cathode, and the anions move toward the anode. These charged resin ions, together with the adsorbed pigment particles, are electrophoresed onto the surface of the workpiece to form a coating. This process is called electrophoresis.
