Cr涂层对Zr-1Nb合金包壳微动磨损行为的影响

Effects of Cr coating on fretting wear behavior of Zr-1Nb alloy cladding

摘要:

反应堆冷却剂流体振动导致的微动磨损已成为压水堆燃料包壳失效的重要原因。Cr涂层锆合金因抗高温蒸汽氧化能力强、耐腐蚀性能优异，成为最具发展前景的事故容错燃料包壳候选材料之一。然而，目前仍缺乏Cr涂层锆合金包壳微动磨损行为及机理的相关研究。本文采用三维白光干涉仪、扫描电子显微镜、能谱仪等表征技术对比研究Cr涂层Zr-1Nb合金包壳和Zr-1Nb合金包壳与格架在模拟压水堆一回路水环境下的微动磨损行为及损伤机制。结果表明，Cr涂层显著提高Zr-1Nb合金包壳的抗微动磨损性能。此外，对磨副为刚凸时，Zr-1Nb合金包壳微动磨损机制以磨粒磨损和剥层磨损为主，而Cr涂层Zr-1Nb合金包壳由于表面硬度较高，且表面形成具有保护作用的三体层，其损伤机制以黏着磨损和材料单向转移为主。对磨副为弹簧时，Zr-1Nb合金包壳微动磨损机制主要为剥层和黏着磨损，Cr涂层Zr-1Nb合金包壳主要为磨粒磨损。

Abstract:

Fretting wear caused by flow-induced vibration is the predominant cause of fuel cladding failure of pressurized water reactor (PWR). The Cr-coated Zr alloy is one of the most promising candidate materials for accident tolerant fuel, due to its outstanding high temperature oxidation resistance and corrosion resistance. However, research of fretting wear behavior and mechanism of Cr-coated Zr alloy cladding relatively little exists. In this paper, the fretting wear behavior and damage mechanism of Cr-coated and uncoated Zr-1Nb alloy cladding with AFA 3G grid under simulated PWR primary water environment were studied contrastively by 3D white light interferometer, scanning electron microscopy and energy disperspective spectroscopy. The results indicated that Cr coating can significantly improve the fretting wear resistance of Zr-1Nb alloy cladding. In addition, for cladding against dimple, the dominant wear mechanism of Zr-1Nb was delamination and abrasive. However, the main damage mechanism of Cr-coated Zr-1Nb was adhesive wear and materials transfer, due to higher surface hardness and formation of protective third body layer. For cladding against spring, the damage mechanism was delamination and adhesive wear for Zr-1Nb, while abrasive wear for Cr-coated Zr-1Nb.