热力耦合作用下石墨烯力学特性的研究

Graphene exhibits excellent mechanical properties, for example, its Young's modulus is as high as ~1TPa and the fracture strength can reach the theoretic value. Researchers thus predicted that graphene can be used in various applications such as nanoelectromechanical system, mass sensor membrane and flexible electronics, etc. However, the mechanical characterization technique for graphene was limited to the ambient condition due to the lack of the efficient instruments. According to molecular dynamic calculations, the service temperature can result in a significant change of the mechanical properties of graphene. With its potential applications in increasing fields, such as information, energy and materials etc, it is important to obtain the mechanical properties of graphene at non-ambient temperatures. The aims of this project are to systematically study the mechanical characteristcs of graphene inlcuding Young's modulus, fracture strength and constitutive relations, under thermo-mechanical coupling conditions (low temperature range: -15oC to room temperature; high temperature range: room temperature to 500oC) using a novel nanoindentation system with high/low temperature capacities, to establish the theoretic model based on the continuum mechanics,to study the possible abnormal physical phenomena and its intrinsic features under the different thermo-mechanical coupling conditions for nano-scale materials,to develop the new testing method and technology for thin films accordingly,The final reseash results are expected to discover the mechanical characteristics and failure mechanism of graphene under thermo-mechanical coupling conditions, and to provide the experimental data and theoretic basis for the applications of graphene.

石墨烯具有极其优异的力学性能，如弹性模量达到1Ta、断裂强度接近理论强度值，可应用于纳米机电系统、质量传感膜和柔性电子系统等领域。但由于缺乏有效的测试手段，对二维尺度石墨烯力学性质的表征局限在常温状态。分子动力学计算结果显示：温度改变将导致其力学性能的显著变化。随着石墨烯在越来越多领域显示出广泛的应用价值，如电子、能源和材料等，准确评价其在非常温条件下的力学特性显得尤为重要。本项目拟采用新型非常温纳米压痕仪系统地研究热力耦合条件下（低温段：-15oC至室温；高温段：室温至500oC）石墨烯力学特性，包括弹性模量，断裂强度及本构关系；基于连续介质力学建立相关理论模型；探讨纳米尺度材料可能具有的异常物理现象及其本征特性；研发相应的薄膜材料力学性能测试新方法和新技术。最终研究结果有望揭示石墨烯在热力耦合条件下的力学特性和失效规律，为其在非常温环境下的应用提供力学实验数据和理论基础。

中文摘要(对项目的背景、主要研究内容、重要结果、关键数据及其科学意义等做简单概述，1000字以内)：. 分别采用化学气相法（CVD）在铜箔上生长高质量石墨烯和化学法制备氧化石墨烯（GO），结合仪器化纳米压痕仪和AFM纳米压入法系统研究其力学行为和相关规律，建立相关物理模型。. 针对CVD生长单/多晶石墨烯的特有力学响应，评价其本征力学性能。通过载荷-位移曲线中不同区域特有的跳跃（pop-in）现象，揭示CVD多晶石墨烯自下而上生长机制。探讨温升条件下，CVD单/多晶石墨烯晶畴的力学响应变化。对石墨烯的化学气相生长机制和热力耦合条件下性能分析提供参考和理论支持。针对GO及其纳米复合材料，系统研究了温度对其成分、键合、显微结构、宏观力学性能和纳米力学性能的关联性。为加深对石墨烯材料的理解、设计和开发石墨烯增强聚合物复合材料理论支持和参考。此外，开发新型氧化石墨烯还原和多元掺杂工艺。本项目的完成，不仅对揭示石墨烯材料的形成机理，单/多晶石墨烯纳米力学性能，以及在热、力耦合条件下特有行为，而且对发展高性能石墨烯材料和拓宽其应用范围，有着重要的意义。