Chromate-free conversion film solution and the method of applying the solution to magnesium alloys

摘要

Disclosed herein is a chromate-free conversion film solution and a method of applying the solution to magnesium and magnesium alloys. The solution contains zirconium ions, manganese ions, barium ions and phosphate corrosion inhibitor; and the pH of the said solution is in the range of 1-5; and may further comprise molybdate as accelerant. The method comprises degreasing, acid etching, surface activation, surface adjusting, and film forming steps. The conversion film obtained in accordance with the disclosed method is uniform, smooth, and compact and has high corrosion resistance and good adhesion with paint film. Moreover, the chromate-free conversion film solution is environmentally friendly and possesses fast film growth rates.