Environmentally friendly chromium-free passivation solution for aluminum and aluminum alloy surface and application thereof

The invention discloses an environmentally friendly chromium-free passivation solution for aluminum and aluminum alloy surface and application thereof. The passivation solution consists of molybdate, fluoroborate, nitrate, boric acid and an acidic catalyst, wherein the molybdate is one or a complex of sodium molybdate and potassium molybdate; the fluoroborate is one or a complex of sodium fluoroborate and potassium fluoroborate; the nitrate is one or a complex of sodium nitrate, potassium nitrate, copper nitrate and calcium nitrate; and the acidic catalyst is one or a complex of nitric acid, sulfuric acid, phosphoric acid and acetic acid. The content of the molybdate is 3-50 g/L, the content of the fluoroborate is 1-20 g/L, the content of the nitrate is 1-15 g/L and the content of the boric acid is 0.1-10 g/L; and the acidic catalyst is used to adjust the pH value to 2-6 and the temperature condition is the room temperature. The aluminum and aluminum alloy workpieces are degreased, descaled, activated and cleaned and then placed in the passivation solution to passivate, and the corrosion resistance of the aluminum alloy can be increased.