Corrosion Resistance of Ceramics Based on SiC under Hydrothermal Conditions

We study the possibility of improvement of the corrosion resistance of ceramics based on silicon carbide (SiC) under the conditions of high-temperature steam corresponding to the standard operating conditions of fuel shells in WWER-1000 (water-moderated water-cooled) power reactors. We formed and sintered SiC specimens with and without admixtures of Cr and Si by the method of high-speed hot pressing in a graphite mold in a vacuum. The corrosion tests were carried out at a temperature of 350°C under a pressure of 16.8 MPa for 1000 h in a water medium used as the heat carrier of the WWER-1000 reactor. The physicomechanical characteristics of SiC ceramics prior to and after the tests were analyzed by the methods of X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Hardness was measured with the help of a PMT-3 microhardness tester. It is demonstrated that the procedure of alloying of silicon carbide with chromium guarantees the most pronounced elevation of its corrosion resistance without decreasing its microhardness and crack resistance.