Department of Mechanical Engineering, Columbia University, New York, NY 10027, USA.
Science. 2013 May 31;340(6136):1073-6. doi: 10.1126/science.1235126.
Pristine graphene is the strongest material ever measured. However, large-area graphene films produced by means of chemical vapor deposition (CVD) are polycrystalline and thus contain grain boundaries that can potentially weaken the material. We combined structural characterization by means of transmission electron microscopy with nanoindentation in order to study the mechanical properties of CVD-graphene films with different grain sizes. We show that the elastic stiffness of CVD-graphene is identical to that of pristine graphene if postprocessing steps avoid damage or rippling. Its strength is only slightly reduced despite the existence of grain boundaries. Indentation tests directly on grain boundaries confirm that they are almost as strong as pristine. Graphene films consisting entirely of well-stitched grain boundaries can retain ultrahigh strength, which is critical for a large variety of applications, such as flexible electronics and strengthening components.
原始石墨烯是迄今为止强度最高的材料。然而，通过化学气相沉积（CVD）生产的大面积石墨烯薄膜是多晶的，因此含有可能削弱材料的晶界。我们通过透射电子显微镜的结构表征与纳米压痕相结合，研究了不同晶粒尺寸的 CVD-石墨烯薄膜的力学性能。我们表明，如果后处理步骤避免了损伤或波纹，CVD-石墨烯的弹性刚度与原始石墨烯相同。尽管存在晶界，但它的强度只是略有降低。直接在晶界上进行的压痕测试证实，晶界几乎与原始石墨烯一样强。完全由良好拼接晶界组成的石墨烯薄膜可以保持超高强度，这对于各种应用至关重要，例如柔性电子和增强组件。
