A facile co-solvent strategy for preparation of graphene nanoplatelet powder: An industrially viable innovative approach

We report an industrially viable promising approach to produce micrometer-sized multilayer graphene nanoplatelet powder (MGNP) in a scalable quantity via microwave-assisted exfoliation of graphite (MEG) and fragmented into MGNP through liquid-phase exfoliation in the co-solvent mixture by kitchen mixer (KM). KM allows rapid delaminating MEG into MGNP by shear force dominated exfoliation. Majority of MGNPs are with a diameter of few micrometers and thickness is in nanometers. MGNP are crystalline with very limited defects was confirmed by Raman measurements and transmission electron microscopy. This process transforms, more than 86% of graphite flakes into MGNP. This advanced approach opens a new pathway to produce MGNP in bulk quantity as it is feasible, rapid, and cost-effective.     

二维无机功能材料

简要介绍了一种通过层状结构材料剥离成单分子层的无机二维功能材料。     

铝-锂合金腐蚀性能研究综述

综述了铝-锂合金孔蚀、晶间腐蚀、应力腐蚀断裂(SCC)及剥蚀的研究现状。阐述了加工状态、热处理、显徽组织及腐蚀介质对一些铝-锂合金孔蚀及晶间腐蚀行为与SCC敏感性的影响及其影响机制．同时报道了一些研究铝-锂合金剥蚀的新方法，并提出了进一步研究的方向．     

直接液相剥离法制备无缺陷石墨烯

石墨烯优良的物理和化学性能,使它日益得到广泛的关注.如何获得高质量高产量的石墨烯对石墨烯未来的开发和应用至关重要.直接液相剥离法制备石墨烯是一种有望实现高质量石墨烯量产化的方法.该方法是在一定介质中通过超声手段将石墨烯晶体从石墨中剥离出来,形成胶体溶液,从而得到石墨烯.通过剥离介质(溶剂及辅助试剂)的筛选可以有效地提高石墨烯的剥离效率.本文主要介绍近年来液相剥离法制备石墨烯的研究进展,讨论了在不同的剥离介质、剥离条件下制得的石墨烯的质量和产量.旨在为未来液相剥离法制备石墨烯的发展提供参考,开发更加有效的剥离体系,研究能够高效生产高性能石墨烯的新方法.     

INTERGRANULAR AND EXFOLIATION CORROSION BEHAVIOUR OF 8090Al-Li ALLOY

The A1-2.79Li-1.3Cu-0.7Mg-0.12Zr(8090) alloy has excellent resistance to intergranularand exfoliation corrosion as naturally aged, worst as peak aged and rather better asunderaged than as overaged. The corrosion behaviour of the alloy is closely dependent on itsmicrostructure. Under the peak aging condition, the coarse T_2 phase, which is continuouslydistributed along grain boundaries, has so low corrosion potential in comparison with the ma-trix, this makes the corrosion resistance of the alloy to be deteriorated by anodic dissolutionalong grain boundaries.     

固溶后预析出对7A55铝合金力学及腐蚀性能的影响

采用硬度测试、电导率测试及透射电镜观察，研究固溶后降温至440℃预析出处理时间对7A55铝合金板材力学和腐蚀性能的影响。结果表明：随预析出处理时间的延长，基体析出相逐渐增多且长大，导致合金时效后硬度和强度先提高而后降低；晶界析出相逐渐长大，晶界无沉淀析出带宽化，晶界相不连续性先提高而后降低，导致合金抗晶问腐蚀和剥落腐蚀性能也先升高而后降低。     

Managing the degree of exfoliation and number of graphene layers using probe sonication approach

We have demonstrated a fast, versatile, and scalable approach to synthesize high-quality few layer graphene sheets with low defect ratio and high crystallinity produced from exfoliation of graphite flakes in DMF by using probe sonication. The effect of sonication time on degree of exfoliation and number of graphene layers has been fully investigated. The degree of exfoliation of graphene sheets as a function of sonication time has been successfully analyzed by XRD, UV-Vis spectroscopy, TEM, and BET studies. The morphological changes at different sonication times have also been observed by SEM. A structural and defect characterization of graphene sheets has been discussed in detail by Raman spectroscopic technique. The shift in position of 2D Raman band and its de-convolution provided information about formation of multi to few layer graphene sheets with sonication. Moreover, Raman results are highly consistent with TEM studies as per number of graphene layers is concerned.     

Flexible Nonvolatile Transistor Memory with Solution‐Processed Transition Metal Dichalcogenides

Nonvolatile field‐effect transistor (FET) memories containing transition metal dichalcogenide (TMD) nanosheets have been recently developed with great interest by utilizing some of the intriguing photoelectronic properties of TMDs. The TMD nanosheets are, however, employed as semiconducting channels in most of the memories, and only a few works address their function as floating gates. Here, a floating‐gate organic‐FET memory with an all‐in‐one floating‐gate/tunneling layer of the solution‐processed TMD nanosheets is demonstrated. Molybdenum disulfide (MoS₂) is efficiently liquid‐exfoliated by amine‐terminated polystyrene with a controlled amount of MoS₂ nanosheets in an all‐in‐one floating‐gate/tunneling layer, allowing for systematic investigation of concentration‐dependent charge‐trapping and detrapping properties of MoS₂ nanosheets. At an optimized condition, the nonvolatile memory exhibits memory performances with an ON/OFF ratio greater than 10⁴, a program/erase endurance cycle over 400 times, and data retention longer than 7 × 10³ s. All‐in‐one floating‐gate/tunneling layers containing molybdenum diselenide and tungsten disulfide are also developed. Furthermore, a mechanically‐flexible TMD memory on a plastic substrate shows a performance comparable with that on a hard substrate, and the memory properties are rarely altered after outer‐bending events over 500 times at the bending radius of 4.0 mm.     

Challenges in Liquid‐Phase Exfoliation,Processing, and Assembly of Pristine Graphene

Recent developments in the exfoliation, dispersion, and processing of pristine graphene (i.e., non‐oxidized graphene) are described. General metrics are outlined that can be used to assess the quality and processability of various “graphene” products, as well as metrics that determine the potential for industrial scale‐up. The pristine graphene production process is categorized from a chemical engineering point of view with three key steps: i) pretreatment, ii) exfoliation, and iii) separation. How pristine graphene colloidal stability is distinct from the exfoliation step and is dependent upon graphene interactions with solvents and dispersants are extensively reviewed. Finally, the challenges and opportunities of using pristine graphene as nanofillers in polymer composites, as well as as building blocks for macrostructure assemblies are summarized in the context of large‐scale production.