Abstract
Developing high-radiation-tolerant inert matrix fuel (IMF) with a long lifetime is important for advanced fission nuclear systems. In this work, we combined zirconia (ZrO2) with magnesia (MgO) to form ultrafine-grained ZrO2–MgO composite ceramics. On the one hand, the formation of phase interfaces can stabilize the structure of ZrO2 as well as inhibiting excessive coarsening of grains. On the other hand, the grain refinement of the composite ceramics can increase the defect sinks. Two kinds of composite ceramics with different grain sizes were prepared by spark plasma sintering (SPS), and their radiation damage behaviors were evaluated by helium (He) and xenon (Xe) ion irradiation. It was found that these dual-phase composite ceramics had better radiation tolerance than the pure yttria-stabilized ZrO2 (YSZ) and MgO. Regarding He+ ion irradiation with low displacement damage, the ZrO2–MgO composite ceramic with smaller grain size had a better ability to manage He bubbles than the composite ceramic with larger grain size. However, the ZrO2–MgO composite ceramic with a larger grain size could withstand higher displacement damage in the phase transformation under heavy ion irradiation. Therefore, the balance in managing He bubbles and phase stability should be considered in choosing suitable grain sizes.
Highlights
Ceramics with high radiation tolerance are often used for radioactive waste management as inert matrix fuel (IMF) and cladding materials for fission reactors [1]
Refining the grain size to increase the density of grain boundaries (GBs) is a widely used method to improve the radiation tolerance
ZrO2 –MgO composite ceramics were prepared by mixing monoclinic ZrO2 powders (99.99%) and cubic MgO powders (99.99%) with a volume ratio of 1:1, and sintered by using spark plasma sintering (SPS)
Summary
Ceramics with high radiation tolerance are often used for radioactive waste management as inert matrix fuel (IMF) and cladding materials for fission reactors [1]. Zirconia (ZrO2 ) is considered to be a promising material for IMF to burn minor actinides, plutonium and to immobilize high-level nuclear waste because of its excellent physical and chemical stability, including thermal and radiation stability and low neutron capture cross-section [2]. To enhance the radiation tolerance of ZrO2 under various energetic particles’ (He, Xe, Cs, and so on) irradiation environments, one of the effective methods is to reduce its grain size. Refining the grain size to increase the density of GBs is a widely used method to improve the radiation tolerance. Materials 2019, 12, 2649 performance of materials. Compared to bulk nickel (Ni), nanocrystalline Ni with an average grain size of 55 nm can significantly reduce the density and size of defect clusters induced by irradiation [5]
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