Preparation and Properties of Chromium-Free Corrosion-Resistant Coatings for Oriented Silicon Steel

An environmentally friendly chromium-free insulating coating suitable for oriented silicon steel was prepared by using aluminium dihydrogen phosphate, silica sol, water-based resin, sodium tetraborate and graphene aqueous dispersion as main raw materials. The morphology of the insulating coating was characterized by scanning electron microscopy. Corrosion resistance was investigated by neutral salt spray test and electrochemical test. Magnetic properties and surface insulating resistance were measured. The results showed that the surface of the insulating coating was flat; the addition of graphene could effectively improve the corrosion resistance and magnetic properties of the coating. The corrosion rate in the salt spray test was less than 10% after 120h, and the core loss was reduced by 9.57%. The addition of the graphene did not destroy the insulation properties of the coating. The surface insulation resistance per side of the coating was 269.51 Ω⋅mm². (paper)