High-ductility periodic variable alloy protective film and forming method thereof

A method for forming a high-ductility periodic variable alloy protective film, comprising steps of:

• (1) providing an aluminum alloy surface or other metal surface for pretreatment, the pretreatment comprising steps of water washing, alkaline washing, water washing, acid washing, pure water washing, passivation, pure water washing, sealing, pure water washing and drying;
• (2) spraying base powder onto the metal surface of step (1) and curing same, the base powder being an epoxy resin powder or pure polyester powder coating;
• (3) performing fine grinding and polishing the surface of step (2);
• (4) cleaning the surface of step (3), comprising steps of water washing, alkaline washing, water washing, acid washing, pure water washing, pure water washing and drying;
• (5) spraying a high-gloss and high-leveling resin powder coating or a solvent-type liquid paint onto the surface of step (4), and curing same, the base paint being epoxy resin powder, a polyester powder coating or a polybutadiene liquid coating;
• (6) performing high-vacuum direct current magnetron sputtering on the surface of step (5), the sputtering comprising simultaneous opening of a NiCr alloy target and a pure Cr metal target and simultaneous auto-rotation and revolution to obtain a periodic variable alloy protective film;
• and
• (7) spraying transparent powder onto the surface of step (6) and curing same, the transparent powder being acrylic resin or a polyester powder coating.