SiC复合包壳热冲击行为分析

为了解决SiC复合包壳热冲击行为模拟存在收敛性差、热冲击性能研究不足的问题，通过模拟冷却剂丧失事故（LOCA）下双层SiC复合包壳内应力状态，采用多物理场耦合的COMSOL软件对SiC复合包壳热冲击行为进行数值模拟，分析了厚度比例、热冲击温度以及端塞对SiC复合包壳的抗热冲击性能的影响。结果表明，热冲击产生的环向应力随化学气相渗透层（CVI层）与 化学气相沉积层（CVD层）厚度比例增大而增大，当CVI层与CVD层厚度比为9: 1时，SiC 复合包壳在热冲击过程中产生的环向拉应力可达113 MPa；热冲击产生的环向应力随热冲击温度差增大而增大，当热冲击温度为1200 K时，产生的环向应力达112.7 MPa；热冲击过程中端塞处有明显应力集中，其径向应力达22.3 MPa，高于文献报道的结合强度（20~25 MPa），是导致端塞连接处失效的主要原因。 

Thermal Shock Behavior Analysis of SiC Composite Cladding

In order to solve the problems of poor convergence and insufficient research on thermal shock performance in the simulation of thermal shock behavior of SiC composite cladding, this paper simulates the internal stress state of double-layer SiC composite cladding under Loss of Coolant Accident (LOCA), uses the COMSOL software of multi-physical field coupling to numerically simulate the thermal shock behavior of SiC composite cladding, and analyzes the effects of thickness ratio, thermal shock temperature and end plug on the thermal shock resistance of SiC composite cladding. The results show that the circumferential stress produced by thermal shock increases with the increase of the thickness ratio of chemical vapor infiltration layer (CVI layer) to chemical vapor deposition layer (CVD layer); When the thickness ratio of CVI layer to CVD layer is 9:1, the circumferential tensile stress of SiC composite cladding during thermal shock can reach 113 MPa; The circumferential stress produced by thermal shock increases with the increase of thermal shock temperature difference. When the thermal shock temperature is 1200 K, the circumferential stress is 112.7 MPa; During thermal shock, there is obvious stress concentration at the end plug, and its radial stress is up to 22.3 MPa, which is higher than the bonding strength reported in the literature (20~25 MPa), which is the main reason for the failure of the end plug connection.