石墨烯界面力学行为的表征与调控研究
发布时间：2018-10-08 12:54
【摘要】：石墨烯拥有独特的二维晶体结构,同时兼具力、电、光、热等诸多优异的物理特性,因此在纳米复合材料、柔性电子器件、微纳机电系统等领域展现出广阔的应用前景。传统理论指出,材料、器件的宏观功能表现很大程度上依赖其界面的结合力和稳定性。而当材料尺寸降至纳米尺度后,原本微弱的非经典力作用(如范德华力、静电力等)变得更加不可忽略,甚至在变形行为中占据主导地位,使得界面力学问题更加显著。另一方面,石墨烯由于具有原子级的厚度以及超高的比表面积,相比于传统材料将引入更多界面相面积,对界面作用力也更加敏感,因此石墨烯也是研究纳米尺度界面摩擦和粘附特性的一个理想选择。本文发展了一个多尺度的实验检测平台,即宏观上实施可控的变形加载,细观上观测显微形貌的演化,微观上测量材料局部的应变响应,进而针对石墨烯与不同材料基底的界面力学性能和行为展开了相关研究,具体研究内容如下:1、研究了单层石墨烯/聚甲基丙烯酸甲酯材料体系在轴向拉伸变形过程中的微观界面力学行为。利用拉曼光谱记录石墨烯在不同应变下的力学响应,结合非线性剪滞模型分析弹性变形和剪切滑移两个阶段的应力传递,获取界面剪切强度、界面刚度等关键力学参数。在此基础上,探讨了多次循环加载条件下界面稳定性,并利用原子力显微镜表征变形过程中表面形貌的演化,分析界面性能改变的微观机制。进一步,通过化学修饰的方法改变石墨烯与基体的键合作用类型,修正非线性剪滞模型指导界面力学性能的微观调控,最终寻求界面的优化设计。2、研究了聚甲基丙烯酸甲酯/石墨烯/聚甲基丙烯酸甲酯“三明治”结构体系在双向压缩变形过程中的微观界面力学行为。利用拉曼光谱探测石墨烯在不同应变下的力学响应,揭示其微观变形演化的三个阶段,即弹性压缩变形阶段,欧拉屈曲变形阶段以及界面局部脱粘阶段。在弹性压缩变形阶段,结合宏观力学载荷和微观局部应变,推算石墨烯的表观压缩模量。在欧拉屈曲变形阶段,分析尺寸和层数对临界屈曲应变的影响,并探究其在多次循环加载条件下的界面稳定性。对于界面局部脱粘阶段,利用拉曼光谱表征界面的失效模式,建立力学模型描述其微观力学行为,提取临界脱粘应变等力学参数。3、研究了鼓泡变形过程中单层石墨烯与硅基底的界面力学性能。发展了基于微孔鼓泡-探针技术-拉曼光谱联用的力学检测平台,其中利用原子力显微镜表征孔内石墨烯的离面位移,采用拉曼光谱监测孔外界面剪切作用区域的可控扩展。在Hencky解的基础上,考虑孔外界面的剪切变形,修正了边界条件,建立力学模型解析石墨烯与硅基底之间的界面剪切应力。同时,通过调控压力载荷使界面产生脱粘,结合理想气体状态方程和能量分析,推算其界面粘附能。利用原子力显微镜观测鼓泡脱粘后的形貌演化,揭示界面剪切滑移变形与边界条件对脱粘行为以及鼓泡形貌的影响。4、研究了多层石墨烯层间界面力学性能的测量与调控。基于上述力学检测平台,我们对双层石墨烯实施可控加载,并监测孔外石墨烯层间剪切作用区域的扩展。结合修正的Hencky理论,首次实现双层石墨烯层间剪切应力的精确测量。利用超低波数拉曼光谱探测多层石墨烯的剪切振动模,结合线性链模型拟合获得层间剪切力常数,并推算层间剪切模量。进一步通过对石墨烯硼掺杂处理实现石墨烯层间距及层间耦合作用的有效调控,探究其对双层石墨烯在纳米压痕试验中力学行为的影响。
[Abstract]:Graphene has a unique two-dimensional crystal structure, and has many excellent physical properties such as force, electricity, light, heat and the like, and therefore, the graphene has a wide application prospect in the fields of nano-composite materials, flexible electronic devices and micro-nano-electromechanical systems. The traditional theory indicates that the macroscopic function of the material and the device depends largely on the binding force and the stability of its interface. When the size of the material drops to the nanometer scale, the original weak non-classical force (such as van der Waals force, electrostatic force, etc.) becomes more and more important, even in the deformation behavior, so that the interfacial mechanics problem becomes more remarkable. On the other hand, because of the thickness of atomic layer and superhigh specific surface area, graphene is more sensitive to interface force than traditional materials, so graphene is an ideal choice for studying the friction and adhesion characteristics of nano-scale interface. In this paper, a multi-scale experimental detection platform is developed, which is to implement controllable deformation loading on a macroscopic scale, observe the evolution of micro-topography on the micro-scale, and measure the local strain response of the material on the micro-scale. The mechanical properties and behavior of the interface between graphene and different materials are studied in this paper. The specific research contents are as follows: 1. The micro-interface mechanical behavior of single-layer graphene/ polymethyl methacrylate material system in axial tensile deformation is studied. The mechanical response of graphene under different strains is recorded by Raman spectroscopy, and the critical mechanical parameters such as interface shear strength, interface stiffness and the like are obtained by combining the nonlinear shear lag model to analyze the stress transfer at two stages of elastic deformation and shear slip. On this basis, the interfacial stability under multiple cyclic loading conditions is discussed, and the evolution of surface morphology during deformation process is characterized by atomic force microscopy, and the micro-mechanism of interface performance change is analyzed. Further, the type of bond cooperation between graphene and matrix is changed by chemical modification, the micro-regulation of mechanical properties of the interface is modified by modifying the nonlinear shear lag model, and the optimization design of the interface is finally sought. "Sandwich" The micro-interface mechanical behavior of the structural system in the two-way compression deformation process. The mechanical response of graphene under different strains is detected by Raman spectroscopy, and the three stages of micro-deformation evolution are revealed, namely, elastic compression deformation stage, Euler buckling deformation stage and interface local debonding stage. In the elastic compression deformation stage, the apparent compressive modulus of graphene is calculated by combining macroscopic mechanical load and micro local strain. In Euler buckling deformation stage, the influence of size and number of layers on critical buckling strain is analyzed, and the interfacial stability under multiple cyclic loading conditions is investigated. In this paper, the failure mode of the interface is characterized by Raman spectrum, the mechanical model is established to describe the micro-mechanical behavior of the interface, and the mechanical parameters such as critical desorption strain are extracted. The mechanical properties of the single layer graphene and the silicon substrate during the deformation of the drum are studied. A mechanical detection platform based on microcellular bubble-probe technology-Raman spectroscopy is developed, which uses atomic force microscope to characterize the off-plane displacement of graphene in pores, and uses Raman spectroscopy to monitor the controllable expansion of the external surface shear region. Based on the Hencky solution, the shear deformation of the external surface of the hole is considered, the boundary condition is modified, and the interfacial shear stress between the graphene and the silicon substrate is analyzed by establishing a mechanical model. At the same time, by regulating the pressure load, the interface is debonded, and the interfacial adhesion energy is calculated by combining the state equation of state and energy analysis. The effects of interfacial shear slip deformation and boundary conditions on debonding behavior and bubble morphology were investigated by atomic force microscopy, and the measurement and control of the interfacial mechanical properties of multi-layer graphene layers were studied. Based on the above-mentioned mechanical detection platform, we can load the double-layer graphene and monitor the expansion of the shearing action area between the outer graphene layers of the hole. Combined with modified Hencky theory, the accurate measurement of shear stress between two layers of graphene layers is realized for the first time. The shear vibration modes of the multilayer graphene are detected by using ultra-low wavenumber Raman spectroscopy, the shear constants of the layers are obtained by combining the linear chain model, and the inter-layer shear modulus is estimated. Further, the effective regulation of graphene layer spacing and inter-layer coupling effect was realized by boron doping treatment of graphene, and the influence of the graphene on the mechanical behavior of the double-layer graphene in the nano-indentation test was investigated.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O613.71
本文编号：2256826
[Abstract]:Graphene has a unique two-dimensional crystal structure, and has many excellent physical properties such as force, electricity, light, heat and the like, and therefore, the graphene has a wide application prospect in the fields of nano-composite materials, flexible electronic devices and micro-nano-electromechanical systems. The traditional theory indicates that the macroscopic function of the material and the device depends largely on the binding force and the stability of its interface. When the size of the material drops to the nanometer scale, the original weak non-classical force (such as van der Waals force, electrostatic force, etc.) becomes more and more important, even in the deformation behavior, so that the interfacial mechanics problem becomes more remarkable. On the other hand, because of the thickness of atomic layer and superhigh specific surface area, graphene is more sensitive to interface force than traditional materials, so graphene is an ideal choice for studying the friction and adhesion characteristics of nano-scale interface. In this paper, a multi-scale experimental detection platform is developed, which is to implement controllable deformation loading on a macroscopic scale, observe the evolution of micro-topography on the micro-scale, and measure the local strain response of the material on the micro-scale. The mechanical properties and behavior of the interface between graphene and different materials are studied in this paper. The specific research contents are as follows: 1. The micro-interface mechanical behavior of single-layer graphene/ polymethyl methacrylate material system in axial tensile deformation is studied. The mechanical response of graphene under different strains is recorded by Raman spectroscopy, and the critical mechanical parameters such as interface shear strength, interface stiffness and the like are obtained by combining the nonlinear shear lag model to analyze the stress transfer at two stages of elastic deformation and shear slip. On this basis, the interfacial stability under multiple cyclic loading conditions is discussed, and the evolution of surface morphology during deformation process is characterized by atomic force microscopy, and the micro-mechanism of interface performance change is analyzed. Further, the type of bond cooperation between graphene and matrix is changed by chemical modification, the micro-regulation of mechanical properties of the interface is modified by modifying the nonlinear shear lag model, and the optimization design of the interface is finally sought. "Sandwich" The micro-interface mechanical behavior of the structural system in the two-way compression deformation process. The mechanical response of graphene under different strains is detected by Raman spectroscopy, and the three stages of micro-deformation evolution are revealed, namely, elastic compression deformation stage, Euler buckling deformation stage and interface local debonding stage. In the elastic compression deformation stage, the apparent compressive modulus of graphene is calculated by combining macroscopic mechanical load and micro local strain. In Euler buckling deformation stage, the influence of size and number of layers on critical buckling strain is analyzed, and the interfacial stability under multiple cyclic loading conditions is investigated. In this paper, the failure mode of the interface is characterized by Raman spectrum, the mechanical model is established to describe the micro-mechanical behavior of the interface, and the mechanical parameters such as critical desorption strain are extracted. The mechanical properties of the single layer graphene and the silicon substrate during the deformation of the drum are studied. A mechanical detection platform based on microcellular bubble-probe technology-Raman spectroscopy is developed, which uses atomic force microscope to characterize the off-plane displacement of graphene in pores, and uses Raman spectroscopy to monitor the controllable expansion of the external surface shear region. Based on the Hencky solution, the shear deformation of the external surface of the hole is considered, the boundary condition is modified, and the interfacial shear stress between the graphene and the silicon substrate is analyzed by establishing a mechanical model. At the same time, by regulating the pressure load, the interface is debonded, and the interfacial adhesion energy is calculated by combining the state equation of state and energy analysis. The effects of interfacial shear slip deformation and boundary conditions on debonding behavior and bubble morphology were investigated by atomic force microscopy, and the measurement and control of the interfacial mechanical properties of multi-layer graphene layers were studied. Based on the above-mentioned mechanical detection platform, we can load the double-layer graphene and monitor the expansion of the shearing action area between the outer graphene layers of the hole. Combined with modified Hencky theory, the accurate measurement of shear stress between two layers of graphene layers is realized for the first time. The shear vibration modes of the multilayer graphene are detected by using ultra-low wavenumber Raman spectroscopy, the shear constants of the layers are obtained by combining the linear chain model, and the inter-layer shear modulus is estimated. Further, the effective regulation of graphene layer spacing and inter-layer coupling effect was realized by boron doping treatment of graphene, and the influence of the graphene on the mechanical behavior of the double-layer graphene in the nano-indentation test was investigated.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O613.71
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