摘要
目的通过激光冲击强化技术增强Cr/Cr N复合涂层的耐磨损性能。方法采用多弧离子镀膜技术在Zr合金表面制备Cr/Cr N复合涂层;使用X射线衍射、扫描电子显微镜和能谱仪等研究激光强化处理后涂层的晶粒尺寸大小、表截面微观形貌和元素分布等;利用微动磨损试验机,研究了不同激光能量对Cr/CrN复合涂层微动磨损性能的影响。结果经不同能量强化后,样品表截面在激光冲击作用下产生了微裂纹,且裂纹数量随激光能量增加而增多。与未处理基体相比,强化后的涂层在硬度、残余压应力以及平均晶粒尺寸方面均有明显改善,其中纳米硬度从5.81 GPa提升到7.76 GPa,残余应力从-462.5 MPa提升到-561.3 MPa,近表面涂层的平均晶粒尺寸从30.26 nm减小到27.06 nm。激光处理前后,Cr/CrN复合涂层微动磨损机制没有发生转变,均以黏着磨损为主,同时伴有氧化磨损和磨粒磨损;60 mJ试样的磨损体积和磨损率均为最低,相比未处理基体分别降低了31.87%和32.71%;100 mJ试样由于过高的激光能量引发了冲击弯曲效应,从而导致涂层表面出现弯曲凸起和裂纹扩展,最终使其耐磨性下降。结论适当激光能量可以提升Cr/CrN复合涂层耐磨性能,而过高的激光能量会破坏涂层表面完整性,从而降低其耐磨性能。
The nuclear fuel cladding tube,as a critical component in nuclear reactors,has its performance directly linked to the safety and efficiency of nuclear energy,as any degradation or failure in these tubes could lead to catastrophic consequences,including radioactive material release and reactor shutdown.Against this backdrop,Cr/CrN coatings have emerged as a focal point in surface modification research for cladding tubes,owing to their excellent wear and corrosion resistance properties,which are particularly vital in environments characterized by high temperatures,neutron irradiation,and chemically aggressive coolants.However,the optimization of their wear resistance to accommodate harsher operational environments,such as those encountered during loss-of-coolant accidents or prolonged exposure to corrosive species,has remained an unresolved challenge.The work aims to introduce an innovative LSP technique to enhance the wear resistance of Cr/CrN composite coatings and explore the effect of varying laser energies on the microstructure and fretting wear behavior of the coatings,addressing a critical gap in current surface engineering strategies for nuclear applications.In the study,Cr/CrN composite coatings were firstly deposited on the surface of zirconium alloy with multi-arc ion plating technology,a method known for its ability to produce dense,adherent films with excellent interfacial bonding strength.Subsequently,advanced analytical tools such as XRD for phase identification,SEM for microstructural observation,and EDS for compositional analysis were employed to comprehensively characterize the Cr/CrN coatings treated with different laser energies.These techniques enabled a detailed understanding of how LSP affected the microstructure,phase composition,and elemental distribution of the coatings.The laser shocking induced microcracks on the cross sections of the coatings,with the number of cracks increasing with the laser energy,which necessitated careful control of process parameters to avoid compromising structural integrity.Compared to the untreated substrate,the laser-peened coatings exhibited significant improvements in hardness,residual compressive stress,and grain size.Specifically,the nano-hardness increased from 5.81 GPa to 7.76 GPa,the residual stress rose from‒462.5 MPa to‒561.3 MPa,and the average grain size of the near-surface coatings was refined from 30.26 nm to 27.06 nm,all of which contributed to enhanced wear resistance and crack closure under service conditions.Regarding the assessment of wear performance,systematic testing was conducted with a custom-designed fretting wear tester,which simulated the relative motion between cladding tubes and fuel pellets under realistic operating conditions.The results revealed that laser treatment did not alter the fretting wear mechanism of the Cr/CrN composite coatings,which was primarily dominated by adhesive wear,accompanied by oxidative wear and abrasive wear.This suggested that LSP primarily enhanced the resistance of the material to these wear modes rather than changing their fundamental nature.Notably,when the laser energy was controlled at 60 mJ,the coating achieved the lowest wear volume and wear rate,representing reductions of 31.87%and 32.71%,respectively,highlighting the importance of precise energy control in LSP for optimal performance,compared to the untreated substrate.Nevertheless,excessively high laser energies(e.g.,100 mJ)triggered shock bending effects,leading to bent protrusions and crack propagation on the coating,which instead diminished the wear resistance of the material,underscoring the need for energy thresholds to avoid detrimental effects in nuclear applications.In summary,this study confirms the effectiveness of appropriate laser energies in enhancing the wear resistance of Cr/CrN composite coatings,while revealing the potential damaging effects of excessively high energies on the coating.These findings provide crucial technical support and theoretical basis for the further optimization and application of Cr/CrN coatings in nuclear fuel cladding tubes,ultimately contributing to the safety and reliability of nuclear energy systems.
作者
唐国灿
曾兵
周俊波
TANG Guocan;ZENG Bing;ZHOU Junbo(School of Mechanical and Electrical Engineering,Chengdu University of Technology,Chengdu 610031,China)
出处
《表面技术》
北大核心
2025年第23期197-207,共11页
Surface Technology
基金
动态极端环境材料技术重点实验室开放基金。
