IMPROVEMENT IN OXIDATION RESISTANCE OF THE NUCLEAR GRAPHITE BY REACTION-COATED SIC COATING

Graphite shows superior nuclear and high-temperature performance, and is used in nuclear reactors with enormous quantities. The oxidation resistance of graphite is very poor. Therefore, the application of graphite is only limited to restricted environment. SiC presents excellent resistance to oxidation because of the growth of a protective glassy or partially crystallized SiO2 layer at the surface of the material. It is reported in this paper that a uniform and dense SiC coating is formed by the reaction of graphite and molten silicon. Oxidation experiments show that, when samples were heated at 1000 degrees C in static air for 8 h, 68 wt% of the graphite was burnt off, whereas for the coated graphite only 1.7 wt%, and 1.0 wt% at 1500 degrees C in air for 2 h.