Potassium fluoride as the main salt, phosphate as additives, citrate or tartrate as the main stabilizer. Fluoride ceramic films obtained by this method are intact and compact, and are firmly bonded with the matrix. They can be used as a protective layer alone, and can be prepared by processing and then treated with more corrosion resistance, abrasion resistance and high hardness of the composite surface functional layer. The whole process has the advantages of simple process, low cost and environment.

The present invention relates to a method for preparing a porous fluoride ceramic film on the surface of magnesium and magnesium alloy, and belongs to the technical field of metal surface treatment. The method comprises the following steps: chemical passivation of magnesium alloy, preparation of single pulse ceramic film and preparation of double pulse ceramic membrane. The chemical passivation comprises a solution of hydrofluoric acid, phosphoric acid and hydrogen fluoride, and the preparation of single and double pulse ceramic membranes is mainly carried out in a fluorine-containing electrolyte system.