SiC材料辐照性能的热释光表征分析研究

Thermoluminescence Characterization of IrradiationProperty of SiC Material

碳化硅(Si C)在航空航天、核裂变和核聚变反应堆等高辐照环境中有着广泛应用。由3c-SiC包覆层构成的TRISO燃料颗粒已商业化并应用于先进的高温气冷堆。其中35μm厚的3c-SiC包覆层是承受内压、阻挡裂变产物释放和高效导出核芯热能的关键层,是保证高温气冷堆安全的关键屏障之一。本文利用热释光(TL)分析对3c-SiC材料展开研究,实验证明SiC材料的发光峰强度随辐照剂量升高而增加。辐照后的发光峰随剂量增加向低温方向移动,遵循TL二阶动力学方程。在辐照环境下载能粒子使Si、C原子偏离晶体格点位置产生过饱和空位、间隙离子、错位原子等点缺陷,新增加了约194.5℃处的发光峰。晶体在生长过程中固有缺陷的浓度依赖于Gibbs自由能、结晶温度的变化,其固有缺陷浓度可以用TL的390℃发光峰表征。这两部分缺陷浓度的增加会使SiC层的包覆性能降低。本文还讨论了SiC材料的TL与Gibbs自由能、结晶温度和固有缺陷浓度的关系,SiC材料的缺陷浓度随结晶温度的增加而降低。本文研究结果对SiC包覆层的缺陷和性能分析有很好的参考价值,对辐照前后SiC包覆层的性能表征有一定的参考意义。

High temperature gas cooled reactor is an advanced type of reactor with fourth generation characteristics,and the core uses fuel elements composed of TRISO fuel particles.Among them,35μm thick 3c-SiC coating layer is a key layer for resistance of internal pressure,preventing the release of fission products,and efficiently conducting core heat energy,and is one of the key barriers to ensure safety.The purpose of this study is to evaluate the defects of 3c-SiC materials and the changes in 3c-SiC defects after irradiation using thermoluminescence(TL)method.Based on the theoretical analysis of intrinsic defects and impurity related defects in the preparation process of SiC materials,the luminescence properties of 3c-SiC materials were experimentally studied using gamma ray irradiation and TL analysis.The TL luminescence intensity of SiC crystal materials increases with increasing irradiation dose.The luminescence peak after irradiation can be described by the TL second-order kinetic equation.Its intrinsic defect concentration can be characterized by the 390℃luminescence peak of TL.In the irradiation environment,downloading energy particles causes Si and C atoms to deviate from the crystal lattice position,resulting in point defects such as supersaturated vacancies,interstitial ions,and misaligned atoms,which are manifested as an additional luminescence peak of 194.5℃approximately.TL is a good method for characterizing defects and analyzing radiation performance of SiC materials.1600℃is the ideal deposition temperature for SiC materials.It has good reference value for studying the defects and performance analysis of SiC coating layers,and has certain reference significance for characterizing the performance of SiC coating layers before and after irradiation.