Normal temperature fast filming fluid for aluminium alloy surface and its usage

[0063] Specific Example 1: Clean the surface of aluminum alloy 3A21 with gasoline, then immerse it in a 3% sodium hydroxide solution at a temperature of 30 to 60°C for 3 minutes for degreasing treatment, and then immerse the alloy in a 5% nitric acid solution at room temperature after washing with water 5 minutes, after rinsing with deionized water, then immerse the surface of the aluminum alloy at room temperature to quickly form a film of hexavalent chromium chemical conversion replacement solution. The composition of the chemical conversion liquid is 0.10 g / L of sodium silicate, 0.5 g / L of titanyl sulfate, 0.5 g / L of hydrogen peroxide, 1 g / L of aluminum sulfate, and 5 g / L of sodium fluoride. Sulfuric acid is used to adjust the pH of the conversion liquid to 2-8, and the temperature is 15-20°C. After reacting for 10 minutes, the aluminum alloy is taken out and washed with water to dry. The formed film has passed the 336-hour neutral salt spray test (ASTM B117) test, and the ...

[0064] Specific embodiment 2: After the aluminum alloy LD2CS is subjected to the same pretreatment as in Example 1, the alloy is immersed in 0.05g / L sodium silicate, 2g / L titanyl sulfate, hydrogen peroxide 0.5g / L, chlorinated In the conversion solution of cerium 2g / L and sodium fluoride 4g / L, sulfuric acid adjusts the pH value of the solution. The reaction conditions are the same as in Example 1. The aluminum alloy LD2CS treated above has formed a layer of white film layer after 336 hours of neutral salt spray (ASTM B117) test and still does not rust. Glue hard.