Abstract
The interest in silicon carbide (SiC-based) ceramics and composites as matrix material for nuclear waste immobilization is grown up. Long-term chemical durability and radiation resistance of SiC are important factors for radionuclides immobilization. Advantages of SiC-based ceramics as structural materials in nuclear applications are the high-temperature properties, high density and reduced neutron activation. The use of radiation resistant materials is a strong requirement for safe and environmentally beneficial energy system. The SiC ceramics stability under irradiation for temperatures up to 1273 K is also very important for nuclear power applications. The SiC matrices doped by additives of Cr, Si were fabricated using High Speed Hot Pressing Method. Additives content was in the range from 0.5 to 3 wt %. Microstructural characteristics of silicon carbide ceramics were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and infra-red spectroscopy (IR) methods. The results of microcracking under indentation conditions were revealed the lack of cracks in the SiC ceramics with Cr additives before and after irradiation process. In addition, it was demonstrated that samples of SiC with alloying additives Cr and Si possess high mechanical parameters under γ-irradiation process. The strength of ceramics increases with the uniform and fine-grained structure formation. The modification of phase composition and mechanical properties of the SiC ceramics with Cr and Si additives under γ-irradiation were analyzed for further development of radiation resistant and matrix materials for radioactive wastes immobilization.
Highlights
The results of microcracking under indentation conditions were revealed the lack of cracks in the silicon carbide (SiC) ceramics with Cr additives before and after irradiation process
It was demonstrated that samples of SiC with alloying additives Cr and Si possess high mechanical parameters under γ-irradiation process
It was demonstrated that samples of SiC with alloying additives Cr and Si possess high mechanical parameters under γirradiation process: microhardness – 32.2 – 29.9 GPa, fracture toughness coefficient K1C = 5.4 – 4.2 MPa∙m1/2, respectively
Summary
SiC-based ceramics and composites possess superior properties, such as high corrosion resistance, excellent chemical and thermal shock stability, high mechanical strength, thermal expansion and small neutron absorption crosssection [1,2,3]. Such properties are very attractive for further operating under extreme environmental conditions, in particular, as matrix material for water-cooled and fusion power reactors, for the nuclear fuel as a cladding material, and us protective form for radioactive waste immobilization [4,5,6]. The resulting microstructural changes may eventually modify the properties of the SiC ceramics [10]
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