SiC/nano α-Al2O3 Double-Layer Coating on Graphite Component via Pack Cementation and Electrophoretic Deposition

Abstract

Abstract Graphite and carbonaceous parts are being extensively employed in industrial and high-tech fields. Since these materials suffer from severe oxidation at elevated temperatures, it is vital to keep them safe from being damaged and corroded at high-temperature working conditions. In this study, a double-layer coating was prepared to achieve this aim. Primarily, SiC was coated on graphite samples via pack cementation method and then a layer of nano α-Al2O3 was coated on it through the electrophoretic deposition (EPD) method to improve the oxidation resistance at high temperatures. This alumina coating was further sintered only for 20 minutes at a relatively low sintering temperature of 1350 ºC in a microwave furnace to densify and close the oxygen permeation paths. Finally, this double-layer fabricated coating could reduce the weight loss by oxidation about 50 times in comparison with the bare graphite. Regarding the excellent oxidation protection performance of this double-layer coating and its feasibility for production scale-up, it can be further investigated to protect various carbon-based engineering materials from oxidation at high temperatures.