Preparation of reduced graphene oxide and its application in chromium-free inorganic insulating coating for oriented silicon steel
Abstract In the fields of military industry, national defence and major engineering, oriented silicon steel is an indispensable material, but the chromium-containing insulating coating coated on its surface is harmful to the environment and humans. Due to poor performance, the industrialization of chromium-free inorganic coating is hindered. To improve the corrosion resistance of chromium-free inorganic insulating coating for oriented silicon steel, reduced graphene oxide (rGO) was prepared by the hydrothermal reduction method and added to the basic chromium-free inorganic insulating coating composed of small-particle silica sol, large-particle silica sol and aluminium dihydrogen phosphate to obtain rGO-containing coating. Scanning electron microscopy (SEM) and Raman spectroscopy were used to analyse the microscopic morphology and structural characteristics of rGO. Electrochemical impedance spectroscopy (EIS) and Tafel polarization curves were used to test the corrosion resistance of the coating. The results show that the prepared rGO has a multi-layer structure with a smaller size than graphene oxide (GO) and can be dispersed in water-based coatings. And rGO can reduce the corrosion current density of the coating by two orders of magnitude, and improve the corrosion resistance of the coating.