【摘要】 U₃Si₂是轻水堆中最具前景的事故容错核燃料之一，有望在未来取代UO₂核燃料而被广泛使用。目前，采用放电等离子烧结（Spark Plasma Sintering,SPS）技术制备U₃Si₂芯块的研究已被广泛报道，但SPS参数对芯块性能的影响还尚不明确。本文采用SPS技术制备了U₃Si₂芯块，并研究了不同烧结温度（1 000～1 300℃）和压力（30～90 MPa）对芯块的力学和热学性能的影响。利用激光导热仪测量了芯块的热扩散率，并计算出芯块的热导率。通过纳米压痕仪测量芯块的力学性能，包括硬度、杨氏模量和断裂韧性。研究结果表明：所制得的U₃Si₂芯块热导率在27～700℃范围内均呈现线性增加的趋势，并随着烧结温度和压力的升高而增大；芯块的硬度和杨氏模量随烧结温度升高而增大，且随着压力的升高呈现先增加后平缓的趋势，并在60 MPa趋于平缓；芯块的断裂韧性随烧结温度升高而降低，并随着烧结压力的升高而增大。基于上述结果，提出了优化的SPS参数。本研究将为高性能U₃Si₂燃料的制备提供参考。更多还原

【Abstract】 [Background] U₃Si₂ is regarded as one of the most promising accident-tolerant nuclear fuels for light water reactors and is expected to replace the UO₂ nuclear fuel in the future. Currently, spark plasma sintering（SPS） is an advanced technique for preparing U₃Si₂ pellets; however, the influence of SPS parameters on the performance of the pellets is unclear. [Purpose] This study aims to investigate the effects of different sintering parameters（temperature and pressure） on the mechanical and thermal properties of the U₃Si₂ pellets prepared using SPS technology. [Methods] The thermal diffusivity of U₃Si₂ pellets was measured using a laser flash apparatus, and the thermal conductivity of the pellets was calculated. The mechanical properties of the pellets, including hardness,Young’s modulus, and fracture toughness, were measured using nanoindenter. Thereafter, the influence of different sintering temperatures in the range of 1 000～1 300 ℃ and pressures in the range of 30～90 MPa on the mechanical and thermal properties of U₃Si₂ pellets were carefully examined. [Results] The measurement results show that the thermal conductivity of the as-synthesized pellets increases linearly with temperature in the range 27～700 ℃.Moreover, increasing the sintering temperature and pressure improves the thermal conductivity of the U₃Si₂ pellets.The hardness and Young’s modulus of the pellets increase with an increase in sintering temperature. They also exhibit a trend of first increasing and then stabilizing with increasing pressure, and tend to fully stabilize at 60 MPa.Moreover, the fracture toughness of the pellets decreases with the increase of sintering temperature and increases with increasing pressure. [Conclusions] Based on the above results, optimized SPS parameters for the U₃Si₂ pellets are proposed, and this study provides a reference for the preparation of high-performance U₃Si₂ pellets.更多还原