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New insights into sono-exfoliation mechanisms of graphite: In situ high-speed imaging studies and acoustic measurements
Materials Today ( IF 24.2 ) Pub Date : 2021-06-24 , DOI: 10.1016/j.mattod.2021.05.005
Justin A. Morton , Mohammad Khavari , Ling Qin , Barbara M. Maciejewska , Anastasia V. Tyurnina , Nicole Grobert , Dmitry G. Eskin , Jiawei Mi , Kyriakos Porfyrakis , Paul Prentice , Iakovos Tzanakis

The application of ultrasound and acoustic cavitation in liquid exfoliation of bulk layered materials is a widely used method. However, despite extensive research, the fundamental mechanisms remain far from being fully understood. A number of theories have been proposed to interpret the interactions between cavitation and bulk layered materials and hence to explain the mechanisms of ultrasound assisted exfoliation. Unfortunately, most of the research reported to date is ambiguous or inconclusive due to lack of direct real-time experimental evidence. In this paper, we report systematic work characterising cavitation emissions and observing the exfoliation of graphite in situ, in deionised water under the dynamic interaction with laser and ultrasound induced cavitation bubbles. Using ultra-high-speed optical imaging, we were able to determine the dynamic sequence of graphite exfoliation events on a time scale never reported before. Real-time observations also revealed that shock waves with a pressure magnitude up to 5 MPa and liquid-jets in the range of 80 ms−1, from transient cavitation bubble implosions, were essential for the initiation and propagation of the exfoliation process. On the other hand, bubble oscillations associated with stable cavitation were beneficial for promoting a gentler delamination of graphite layers.



中文翻译:

石墨声剥离机制的新见解:原位高速成像研究和声学测量

超声和声空化在块状层状材料的液体剥离中的应用是一种广泛使用的方法。然而,尽管广泛 研究,其基本机制仍远未完全了解。已经提出了许多理论来解释空化和块状层状材料之间的相互作用,从而解释超声辅助剥离的机制。不幸的是,由于缺乏直接的实时实验证据,迄今为止报告的大多数研究都是模棱两可的或没有定论。在本文中,我们报告了表征空化排放的系统工作,并在与激光和超声诱导的空化气泡的动态相互作用下,在去离子水中观察了原位石墨的剥落。使用超高速光学成像,我们能够以前所未有的时间尺度确定石墨剥落事件的动态序列。-1,来自瞬时空化气泡内爆,对于剥离过程的启动和传播是必不可少的。另一方面,与稳定空化相关的气泡振荡有利于促进石墨层更温和的分层。

更新日期:2021-06-24
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