The invention provides a preparation method of a
magnesium alloy surface micro-arc oxidation /
spray coating compound film, which relates to a preparation method of a
magnesium alloy surface compound film. The invention solves the problems that film
layers obtained by
chemical composition coating,
anodic oxidation and vapor deposition in the existing
magnesium alloy surface treatment method are thin and have poor
corrosion resistance performance, the
ion injection has high cost and is difficult to realize large-area
processing, the combining force between
coating layers and the
magnesium alloy is poor, and organic
coating layers has the defect of easy aging. The preparation method has the following steps: firstly, using micro-arc oxidation for preparing
ceramic films on the surface of the
magnesium alloy; then, adopting air
spray coating for spraying and coating inorganic paint onto the
ceramic films; and then, carrying out heat treatment to obtain the micro-arc oxidation /
spray coating compound film. The method is simple, and the cost is low. The air spray coating uses porous structures of the micro-arc oxidation
ceramic films, so the combination of the inorganic coating layers and the ceramic films is firm, the thickness of the compound films is between 20 and 40 mum, the self
corrosion electric potential is positively moved to -1.02 V, the
corrosion current density is lowered by 5 orders through being compared with that of the
magnesium alloy, the magnesium
alloy surface micro-arc oxidation / spray coating compound film has no damage after 72 to 144h of salt spray tests, and the corrosion resistance performance is good.