Nickel seal is to add insoluble solid particles (Sio2, etc.) with a diameter of 0.01~~1um in the general bright nickel solution, and with the help of an appropriate co-deposition accelerator, these particles and nickel are co-deposited to form a composite nickel plating layer . When a chromium layer is deposited on the surface of this composite nickel plating layer, since the solid particles on the surface of the composite nickel plating layer are non-conductive, chromium cannot be deposited on the surface of the particles, so a large number of micropores are formed on the entire chromium plating layer, that is, the formation of Microporous chrome layer. There are a large number of large micropores on the surface, which can largely eliminate the huge internal stress in the ordinary chromium layer, thus reducing the stress corrosion of the coating, and the most important thing is that the large number of micropores on the chromium layer will reduce the chromium layer below. The nickel layer is exposed in a large area. Under the action of the corrosive medium, the chromium and nickel form a corrosion battery. The chromium layer is the cathode, and the nickel layer exposed at the micropores is the anode and is corroded, thus changing the corrosion mode of the large cathode and small anode. , so that the corrosion current is almost dispersed on the entire nickel plating layer, thereby preventing the generation of large and deep corrosion grooves and pits that go straight through the base metal, and reducing the corrosion rate of the plating layer and developing it laterally, thus It protects the base metal and significantly improves the corrosion resistance of the coating.