Toughening mechanisms and mechanical properties of graphene nanosheet-reinforced alumina
Toughening mechanisms and mechanical properties of graphene nanosheet-reinforced alumina
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DOI：
10.1016/j.matdes.2015.09.125
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发表时间：
2015-12-25
影响因子：
8.4
通讯作者：
Zhu, Yanqiu
中科院分区：
文献类型：
--
作者：
Ahmad, Iftikhar;Islam, Mohammad;Zhu, Yanqiu
采用高频感应加热烧结（HFIHS）技术来制造高密度（>99.5%）石墨烯增强氧化铝纳米复合材料。混合粉末在高达 1500 摄氏度的温度下与 0.25 至 3.0 wt.% 的剥离石墨烯纳米片 (GNS) 进行固结。与整体氧化铝相比，晶粒尺寸细化了 46%，断裂韧性（72%）和硬度值（7%）也随之增加。电子显微镜显示，剥离的 GNS 保留了其固有的平面结构，以抵抗快速烧结引起的任何可能的化学和/或热不利影响。 GNS 固有的二维片状形态和柔韧性促进了大 Al2O3/GNS 界面面积的形成，从而通过晶粒锚定形成了主导的增强机制。晶界区域存在的 GNS 不仅通过钉扎效应抑制晶粒生长，还通过诱导滑粘现象改变纳米级的摩擦特性，通过提高石墨烯拔出和裂纹桥接的效率来提高 Al2O3/GNS 界面强度，从而赋予复合材料韧性并改变复合材料的失效行为。通过高分辨率 TEM 研究建立了 GNS 掺入 Al2O3 基体与由此产生的机械性能之间可能的相关性，该研究表明石墨烯/氧化铝界面的形成不存在任何严重的中间相。 (C) 2015 Elsevier Ltd. 保留所有权利，
High-frequency induction heat sintering (HFIHS) technology was employed for fabrication of highly dense (>99.5%) graphene-reinforced alumina nanocomposites. The mixed powders were consolidated at temperatures up to 1500 degrees C with 0.25 to 3.0 wt.% exfoliated graphene nanosheets (GNS). Compared with monolithic alumina, there was grain size refinement by 46% with an associated increase in the fracture toughness (by 72%) and hardness values (7%). Electron microscopy revealed that exfoliated GNS retained their inherent planar structure against any possible chemical and/or thermal adverse effect caused by rapid sintering. The intrinsic 2-dimensional sheet morphology and flexibility of the GNS promoted formation of large Al2O3/GNS interfacial area, thus leading to a dominant reinforcing mechanism via grain anchoring. The presence of GNS at the grain boundary areas not only inhibited grain growth through pinning effect, it also modified friction traits at nanoscale level by inducing slip-stick phenomenon that increased the Al2O3/GNS interfacial strength by means of improved efficiency of graphene pull-out and crack-bridging that subsequently imparted toughness and altered the failure behavior of the composites. A possible correlation between GNS incorporation into Al2O3 matrix and the resulting mechanical properties is established through high-resolution TEM studies that indicated graphene/alumina interface formation without any presence of severe intermediate phases. (C) 2015 Elsevier Ltd. All rights reserved,