Fluorocarbon spraying is a high-grade spraying method in electrostatic spraying of industrial aluminum profiles. The requirements for spraying quality are very strict. Pretreatment steps should be carried out before spraying to facilitate the smooth progress of the surface treatment process of industrial aluminum profiles. The fluorocarbon spray pretreatment mainly adopts a chemical oxidation treatment method.
The chemical oxidation mainly adopts the method of oxidizing chromic anhydride. As the undercoat layer for coating, the thickness of the oxide film is only 0.5-4 μm, which is porous but not wearable, but has certain adsorption capacity and corrosion resistance. The chemical oxidation method can be used for industrial aluminum profiles of complex shapes and sizes, and the production efficiency is very high, the operation is simple, and the application is very extensive.
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According to the process requirements, chemical oxidation can be divided into acidic oxidation and alkaline oxidation. There are many processes for acid oxidation, such as non-metal oxide chromium trioxide 3.5-4.0g/L and metal element NaF1.0g/ L was reacted at room temperature for 3 min; alkaline oxidation was carried out by dissolving Na2CO340-60 g/L in a 2-3 g/L sodium hydroxide solution, and reacting at 80-100 ° C for 5-10 min. Generally, the acid oxide film has higher corrosion resistance than the alkaline oxide film.
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The main process flow of chemical oxidation is as follows:
Industrial aluminum profile→degreasing (50-60°C, 5min)→hot water washing→cold water washing→alkaline washing (NaOH40g/L, 40-55°C)→water washing→water washing→neutralization (lighting)→water washing→chemical oxidation→water washing→ Pure water washing → drying (80°C, 10-15 min) or blocking treatment (acid oxidation, alkaline oxidation)
