摘要
针对SiC/SiC_(f)复合材料包壳管,采用三点弯加载方法,在模拟压水堆一回路水化学工况的高温高压水中开展了应力腐蚀开裂(SCC)试验,通过腐蚀形貌分析了该材料的抗SCC能力。结果表明:在三点弯加载和高温高压水环境的作用下,该复合材料包壳管外涂层发生氧化及腐蚀溶解,部分区域出现裂纹扩展和涂层剥落现象,而涂层剥落又进一步加剧了外涂层的腐蚀溶解,导致外涂层过早失效和SiC纤维层暴露;在应力和水化学环境的耦合作用下,中间层SiC纤维出现腐蚀溶解和裂纹扩展现象,SiC纤维层表面的裂纹扩展没有明显的取向性,交叉裂纹的不断产生最终导致纤维层的断裂和整体失效。在涂层表面的孔隙缺陷处易产生应力集中,从而成为裂纹萌生位置,需优化涂层制备工艺。
The stress corrosion cracking(SCC)test of SiC/SiC_(f)composite cladding tube in high temperature and high pressure water was carried out by three-point bending loading method,which simulated the chemical conditions of PWR primary water.The SCC resistance of the material was analyzed by corrosion morphology.The results show that under the action of three-point bending loading and high temperature and high pressure water environment,the outer coating of the composite cladding tube was oxidized and corroded,and crack propagation and spalling occurred in some areas.The spalling of the coating further aggravated the corrosion and dissolution of the outer coating,resulting in premature failure of the outer coating and exposure of the SiC fiber layer.Under the coupling effect of stress and water chemical environment,corrosion dissolution and crack propagation appeared in the interlayer of SiC fiber.The crack propagation on the surface of the SiC fiber layer had no obvious orientation,and the continuous generation of cross cracks eventually led to the fracture and overall failure of the fiber layer.Stress concentration was easy to occur at the pore defects on the coating surface,which becomed the location of crack initiation.It is necessary to optimize the coating preparation process.
作者
汪峰
肖嘉
WANG Feng;XIAO Jia(Division of Nuclear Energy and Technology,State Power Investment Corporation Research Institute,Beijing 102209,China)
出处
《腐蚀与防护》
CAS
CSCD
北大核心
2024年第6期75-80,共6页
Corrosion & Protection