核辐照影响锆合金的微动磨损特性研究

In view of the extreme working conditions, including the nuclear irradiation, high temperature, fretting and so forth, safe and stable application of nuclear fuel rod cladding tube become a particularly important problem in reality. This proposal aims to develop a multi-scale fretting wear model and to reveal the mechanism of fretting wear process by combining the experimental tests together with theoretical analysis. Three main issues are considered here: the characterizes as well as the relevant evolution rules of the microstructures affected by the irradiation is explored by examining the surface properties, microstructure, formation and distribution of the defects, transition of intermediate phase and so forth. On the basis of fretting wear tests, the fretting wear property as well as its influence factors of the Zr alloy will be studied in detail, and the running condition fretting map (RCFM) and material response fretting map (MRFM) are expected to be established accordingly. The multi-scale fretting wear model will be developed by combining the molecular dynamics and continuum mechanics, and the mechanism of the fretting wear is revealed eventually. The achievements of this proposal will provide an important theoretical reference and application basis for the safe and stable application of the key components used in the nuclear power industry.

围绕辐照、高温、微动等苛刻条件下，核电燃料棒包壳管安全稳定运行难题。本项目拟采用试验研究与理论分析相结合方法，以建立多尺度微动磨损理论模型、揭示微动磨损机理为目标。重点突破三个关键问题：通过对辐照后锆合金材料表面特性、微观结构、缺陷的形成及其分布、中间相特征及组织结构变化等研究，探讨锆合金受辐照影响后微观组织结构特征及变化规律；在系统微动磨损试验工作基础上，研究受辐照影响锆合金的微动磨损特性及其影响因素，建立运行工况微动图(RCFM)和材料响应微动图(MRFM)；运用分子动力学与连续介质力学耦合方法，建立多尺度微动磨损理论模型、揭示微动磨损机理。该项目研究成果为核电关键零部件安全稳定运行提供重要的理论参考和应用技术基础。

核电燃料棒包壳管是核电系统的关键部件。核电站生产运行中，由于介质流动和热传递导致定位格架的弹簧／刚凸与燃料棒包壳之间产生微动磨损，导致传热管局部损伤甚至破裂，使用寿命降低，危及核电安全。本研究研制了新型多功能微动磨损试验机并获得国家发明专利，实现了模拟常温、高温法向交变载荷下的微动磨损试验。本项目选用锆Zr-4合金, 开展了辐照损伤对锆合金材料表面特性、微观结构的形成及其分布等研究，在不同环境下, 系统地进行了试验研究，研究辐照损伤对微动运行行为和微动磨损特性的影响规律，揭示了微动的区域特性，建立了其运行工况微动图和材料响应微动图。在不同环境（常温、高温）法向交变载荷下辐照后锆合金包壳材料微动损伤强烈地依赖于载荷、温度、频率以及位移等试验参数，从表面损伤形貌看，径向频率和温度对磨痕形貌、磨屑成分及结构有重要影响，揭示了锆合金微动磨损机制。在试验研究的基础上，基于分形理论，建立了多晶锆分形粗糙表面摩擦行为分子动力学理论模型，研究了速度、温度、表面粗糙度等参数对多晶锆摩擦行为影响规律，进而从微观尺度深刻揭示了多晶锆损伤机理。相关研究不仅可以丰富微动摩擦学的基础理论，其成果对核电关键设备长寿命稳定运行具有重要的实际应用价值。