Corrosion Resistance of Ceramics Based on SiC under Hydrothermal Conditions
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CORROSION RESISTANCE OF CERAMICS BASED ON SiC UNDER HYDROTHERMAL CONDITIONS К. V. Lobach,1, 2 S. Yu. Sayenko,1 V. А. Shkuropatenko,1 V. М. Voyevodin,1, 4 H. V. Zykova,1 V. А. Zuyok,1 A. О. Bykov,3 L. L. Тоvazhnyans’kyy,3 and O. М. Chunyaev3 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. Keywords: fuel shell, silicon carbide, alloying, corrosion, microhardness, crack resistance.
Introduction The necessity of development of alternative materials for the fuel shells in water-moderated water-cooled power reactors (WWER) became especially clear after accident at the Fukushima-1 nuclear power plant (NPP). The material based on SiC proves to be most promising for the shells of fuel elements (FE) within the framework of the concept of development of tolerant fuels [Accident Tolerant Fuel (ATF)]. This is explained by its favorable properties, such as radiation and high-temperature chemical resistance and strength [1]. In [2], one can find the results of recent investigations of the resistance of SiC composites to hydrothermal corrosion and corrosion in high-temperature steam, which correspond to the normal and emergency conditions of operation of WWER-1000 reactors, in view of the possibility of application of these composites in fuel shells. It was shown that, under the emergency conditions, high-purity SiC materials have higher resistance to hightemperature steam as compared with Zr1%Nb zirconium alloys due to the formation of SiO 2 films on the surfaces [3]. However, despite its high corrosion resistance in high-temperature steam, the SiC- based ceramics dissolve in high-temperature water, i.e., not in the process of emergency operation. In view of these facts, it is important and necessary to study the possibility of improvement of the corrosion resistance of ceramics and 1 2 3 4
“Kharkiv Institute of Physics and Technology,” National Scientific Center, Kharkiv, Ukraine. Corresponding author; e-mail: [email protected].
“Kharkiv Polytechnic Institute,” National Technical University, Kharkiv,
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