石墨烯断裂性能及其膜基结构界面脱粘演化的多尺度模型及实验表征

There are two types of typical failure modes of graphene/substrate structures: graphene fracture and interfacial debonding. The investigations on the physical mechanism of two failure modes are of great significance for the applications of the graphene/substrate structures in the fields of flexible electronic devices, etc. In this project, the trans-scale correlation between atomic interactions and macroscopic mechanical properties of graphene will be studied. Simultaneously, the influence of geometrical and physical parameters of graphene, including defects, grain boundaries, pre-crack and residual strain, etc., will be taken into account. The multi-scale models will be presented to quantitatively characterize fracture properties of graphene, interfacial stress transfer and interfacial debonding evolution of graphene/substrate structures. Furthermore, graphene fracture and interfacial debonding are studied together for a graphene/substrate structure, and the relationships between graphene fracture and interfacial stress transfer will be analyzed. The critical conditions and microscopic mechanism of mutual competition of two failure modes will be explored, and the critical conditions of graphene/substrate structures will be derived. In addition, the AFM probe, high-resolution electron microscopy and micro-Raman spectroscopy will be comprehensively applied in this project. The Raman spectrum, including peak position, frequency shift, intensity and full width at half-maximum, etc., will be deep studied, the reference spectrum of graphene will be accurately calibrated, and the AFM mapping will be also applied. In this way the material parameters, including defects and residual strain, etc., can be measured. A high-resolution micro-tensile device will be developed, and the fracture properties of graphene, interfacial stress transfer and interfacial debonding evolution of graphene/substrate structures can be in-situ quantitatively characterized.

石墨烯膜基结构存在两类典型失效形式：石墨烯断裂和膜基结构界面脱粘，对其失效机理的研究对该类结构在柔性电子器件等领域的应用具有重要意义。本申请项目拟建立石墨烯原子尺度物理特性和宏观力学性能之间的跨尺度关联，同时考虑缺陷、晶界、预裂纹及残余应变等因素的影响，建立可以定量表征石墨烯断裂力学性能、石墨烯与基体之间界面应力传递以及脱粘演化的多尺度模型。综合考虑石墨烯断裂和膜基结构界面脱粘，分析界面应力传递和石墨烯断裂性能之间的关系，考察两种失效形式的临界条件和相互竞争的微观机理，建立石墨烯膜基结构失效的临界条件。综合应用AFM探针、高分辨率电镜和拉曼光谱技术，深入研究拉曼谱线峰位、频移、光强与半高宽等数据信息，对基准谱线进行准确标定，结合AFM探针扫描技术，定量表征石墨烯的缺陷、残余应变等材料信息。研制高分辨率的微拉伸装置，原位定量表征石墨烯的断裂性能、膜基结构的界面脱粘演化规律。

石墨烯膜基结构存在两类典型失效形式：石墨烯断裂和膜基结构界面脱粘，对其失效机理的研究对该类结构在柔性电子器件等领域的应用具有重要意义。本项目建立了含预裂纹单晶/多晶石墨烯的原子尺度模型，采用基于分子结构力学的有限元法，得到了石墨烯的失效强度、失效应变以及断裂韧性。基于固体物理和量子断裂力学理论，导出了含预裂纹石墨烯失效强度和断裂韧性的解析表达式。分析了石墨烯几何尺寸、裂纹长度和方向角、裂尖半径以及多晶石墨烯的晶界向错角等因素对石墨烯断裂韧性的影响，并探讨了经典断裂力学理论的适用范围。从原子尺度研究了石墨烯的粘附力学行为。建立了原子/离子与理想平整石墨烯以及具有正弦波表面形貌石墨烯之间相互作用的理论模型，导出了他们之间相互作用势和相互作用力的解析表达式。分析了石墨烯手性、缺陷以及表面形貌特征等因素对原子/离子所受法向及切向力的影响。建立了石墨烯膜基结构的二维非线性剪滞模型，研究了石墨烯膜基结构的双向界面切应力传递及脱粘问题。利用分子动力学模拟，研究了石墨烯膜基结构在法向和切向载荷作用下的界面应力传递和失效问题，分析了基体厚度、载荷加载角度和基体晶粒尺寸等对膜基结构界面力学行为的影响。研究了石墨烯/孪晶铝基复合结构在单轴拉伸载荷作用下的失效行为和微观变形机制。基于原子力显微探针，提出了分子尺度的苯环结构与石墨烯间界面相互作用力的实验测试方法，首次实验得到了单个苯环结构与石墨烯之间的粘附力，并研究了环境因素和石墨烯边缘效应对粘附和脱粘力学行为的影响。基于微拉伸实验装置和微拉曼实验技术原位测量了双层石墨烯/PET结构在单轴拉伸作用下的界面应力传递和脱粘演化。采用拉曼光谱分峰方法，实现了全场应变信息的提取，得到了石墨烯层间以及石墨烯基底间的界面切应力分布。相关研究成果对基于石墨烯的高灵敏传感器、污水净化、药物输运以及柔性电子器件等的设计和应用有重要的指导意义。