Barkley Stuart J, Lawrence Adam R, Zohair Murtaza, Smithhisler Olivia L, Pint Cary L, Michael James B, Sippel Travis R
Department of Mechanical Engineering, Iowa State University, Ames Iowa 50011, United States.
ACS Appl Mater Interfaces. 2021 Aug 25;13(33):39678-39688. doi: 10.1021/acsami.1c04476. Epub 2021 Jul 7.
This effort demonstrates the development of a novel, graphene oxide nanoscale thermite composite with thermally tunable microwave ignitability. A model thermite system containing nanoscale aluminum and nanoscale iron(II) oxide in a stoichiometric ratio (30/70 wt %) was combined with sheets of graphene oxide (GO) or reduced graphene oxide (rGO) using an immiscible two-fluid sonication and tape casting process. The samples were microwave irradiated within a single-mode resonant microwave cavity to determine the microwave ignition delay. Neat thermites were found to ignite after 4.34 s of microwave illumination, whereas 30 wt % rGO thermite composite ignition delay was an order of magnitude shorter (0.43 s). For most samples (4 of 6 trials), it was found that application of a 30 wt % GO coating inhibits microwave ignition of the thermite. Thermal treatment of the GO thermite composite led to switching of thermites from unignitable to ignitable with microwave field application as short as 0.24 s due to GO reduction. Optimum heat treatment time and GO content are explored with SEM, DSC/TGA-MS, Raman, and XPS deconvolution. This effort demonstrates the use of GO and rGO addition to achieve thermally switchable microwave ignitability to electromagnetically shield or enhance nanoscale energetic ignition by microwave energy.
这项工作展示了一种新型的氧化石墨烯纳米级铝热剂复合材料的开发，该材料具有热可调的微波可燃性。使用不混溶的双流体超声处理和流延成型工艺，将化学计量比（30/70 wt%）的包含纳米级铝和纳米级氧化铁的模型铝热剂体系与氧化石墨烯（GO）片或还原氧化石墨烯（rGO）片相结合。在单模谐振微波腔内对样品进行微波辐照，以确定微波点火延迟。发现纯铝热剂在微波照射4.34秒后点火，而30 wt%的rGO铝热剂复合材料的点火延迟缩短了一个数量级（0.43秒）。对于大多数样品（6次试验中的4次），发现施加30 wt%的GO涂层会抑制铝热剂的微波点火。由于GO的还原，对GO铝热剂复合材料进行热处理后，在施加短至0.24秒的微波场时，铝热剂从不可燃转变为可燃。通过扫描电子显微镜（SEM）、差示扫描量热法/热重-质谱联用（DSC/TGA-MS）、拉曼光谱和X射线光电子能谱反卷积（XPS）对最佳热处理时间和GO含量进行了探索。这项工作展示了通过添加GO和rGO来实现热可切换的微波可燃性，以进行电磁屏蔽或通过微波能量增强纳米级高能点火。
