Acid oxidation
The mass concentration of the composition/g·L
①The oxide film obtained by formula 1 is relatively thin, with good toughness and good corrosion resistance. It is suitable for aluminum and aluminum alloys that need to be deformed after oxidation, and can also be used for surface protection of aluminum castings, without passivation or filling after oxidation. deal with.
②The pH value of the solution of formula 2 is 1.5～2.2, and the oxide film obtained is thicker, about 1～3 microns, with good compactness and corrosion resistance, the size of the parts does not change after oxidation, and the color of the oxide film is colorless to light blue Color, suitable for all kinds of aluminum and aluminum alloy oxidation treatment. After oxidation treatment in formula 2 solution, parts should be cleaned with cold water immediately, and then filled with potassium dichromate 40～50g/L solution (adjusted with sodium carbonate when PH=4.5～6.5), temperature 90～95℃, time 5-10 minutes, dry at 70℃ after washing.
③The oxide film obtained in the solution of formula 3 is colorless and transparent, with a thickness of about 0.3-0.5 microns, and the film has good conductivity. It is mainly used for deformed aluminum electrical parts.
④Formulation 4 is suitable for pure aluminum, rust-proof aluminum, cast aluminum and other alloys. The oxide film is very thin, has good conductivity and corrosion resistance, low hardness, and is not wear-resistant. It can be spot welded or argon arc welded, but not tin welded; it is mainly used for aluminum alloy parts that require certain electrical conductivity.
⑤The oxide film obtained by formula 5 is relatively thin, about 0.5 microns, has good conductivity and corrosion resistance, and has few pores. It can be used as a protective layer alone.
Alkaline oxidation
The mass concentration of the composition/g·L
①Formula 1 and 2 are suitable for chemical oxidation of pure aluminum, aluminum-magnesium alloy, aluminum-manganese alloy and aluminum-silicon alloy. The color of the film is golden yellow, but the color of the oxide film obtained on the latter two alloys is darker. The film obtained in the alkaline oxidizing solution is softer, has poor corrosion resistance, high porosity, and good adsorption, and is suitable for coating bottom layer.
② Adding sodium silicate to formula 3, the oxide film obtained is colorless, with slightly higher hardness and corrosion resistance, and slightly lower porosity and adsorption. It can be sealed in a 2% solution of sodium silicate. Used alone as a protective layer, suitable for oxidation of aluminum alloys containing heavy metals.
③In order to improve the corrosion resistance of the workpiece after oxidation treatment, it can be passivated in 20g/L CrO3 solution at room temperature for 5-15s, and then dried at a temperature lower than 50℃.