碳纳米管增强UO2燃料力学性能研究  

Study on Mechanical Properties of CNTs Reinforced UO2 Fuel

作　　者：吴学志[1] 尹邦跃[1] 郑新海[1] WU Xuezhi;YIN Bangyue;ZHENG Xinhai(Reactor Engineering Technology Research Division,China Institute of Atomic Energy,Beijing 102413,China)

机构地区：[1]中国原子能科学研究院反应堆工程技术研究部,北京102413

出　　处：《材料导报》2020年第S01期153-156,共4页Materials Reports

摘　　要：利用粉末冶金法制备碳纳米管(CNTs)增强二氧化铀(UO2)复合燃料芯块,研究了复合燃料的弯曲强度、压缩强度和硬度等力学性能,分析了CNTs掺杂量和长径比(L/D)对复合燃料力学性能的影响规律,探讨了CNTs的增强机理。结果表明:随CNTs掺杂量的增加,UO2-CNTs复合燃料的弯曲强度、压缩强度和硬度都有所提高,当掺杂CNTs体积含量为12%时,复合燃料的弯曲强度、压缩强度和硬度达到峰值,分别提高约45.65%、37.01%和19.61%,当掺杂CNTs体积含量超过12%后,复合燃料的力学性能增加呈下降趋势;掺杂不同L/D的CNTs对复合燃料力学性能影响不同,当掺杂CNTs的L/D为9×10^3时,复合燃料的弯曲强度、压缩强度和硬度提高最大,分别提高约57.61%、54.32%和34.87%。SEM分析表明,掺杂适合体积含量和L/D的CNTs是影响复合燃料力学性能的关键因素,否则会导致CNTs在UO2基体中团聚,不利于燃料力学性能的提高;CNTs对UO2燃料力学性能的强化源于外部载荷从UO2基体向CNTs的转移过渡,通过纤维桥联、纤维拔出吸收断裂功,改变裂纹行为等方式来实现。Carbon nanotubes(CNTs)reinforced UO2 fuel pellets were prepared by powder metallurgy,the flexural strength,compressive strength and hardness of composite fuels were studied,the effects of CNTs doping amount and length-diameter ratio(L/D)on the mechanical properties of composite fuels were analyzed,the strengthening mechanism of CNTs was discussed.The results show that with the increase of CNTs doping,the flexural strength,compressive strength and hardness of UO2-CNTs composite fuel increased,when the volume content of CNTs was 12%,the flexural strength,compressive strength and hardness of the composite fuel reached their peak values,which increased by 45.65%,37.01%and 19.61%,respectively,when the volume content of CNTs exceeded 12%,the mechanical properties of the composite fuel increased in a downward trend.The effects of CNTs doped with different length-diameter ratio(L/D)on the mechanical properties of composite fuels were diffe-rent,when the length-diameter ratio(L/D)was 9×10^3,the flexural strength,compressive strength and hardness of the composite fuel increased by 57.61%,54.32%and 34.87%respectively.SEM analysis showed that doping CNTs with suitable volume fraction and length-diameter ratio(L/D)are the key factor affecting the mechanical properties of composite fuel,otherwise CNTs will agglomerate in UO 2 matrix,which is not conducive to the improvement of mechanical properties of fuel.The enhancement of mechanical properties of UO2 fuel by CNTs results from the transition of external load from UO 2 matrix to CNTs,which is realized by means of fiber bridging,fiber pulling-out,absorbing fracture energy and changing crack behavior.

关 键 词：二氧化铀 碳纳米管 复合燃料 弯曲强度 压缩强度 硬度 

分 类 号：TL352.21[核科学技术—核技术及应用]