Gas permeability of graphite foil prepared from exfoliated graphite with different microstructures
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Gas permeability of graphite foil prepared from exfoliated graphite with different microstructures Andrei V. Ivanov1,* , Natalia V. Maksimova1 , Mikhail S. Manylov1 Igor L. Kalachev1 , Artem P. Malakho1 , and Victor V. Avdeev1 1 2
, Alexey N. Kirichenko2
,
Chemistry Department, Lomonosov Moscow State University, Moscow, Russia 119991 Federal State Budgetary Institution ‘ Technological Institute for Superhard and Novel Carbon Materials’’, Troitsk, Moscow, Russia 142190
Received: 29 July 2020
ABSTRACT
Accepted: 4 November 2020
Graphite foil (GF) is widely used as a sealing material in different industries. Different methods of GF preparation result in differences of its crystalline and pore structure, which in turn influences its ability to pass through gases and provide the required level of sealability. The influence of the preparation temperature of exfoliated graphite (EG) on the microstructure and gas permeability of EG-based graphite foil was investigated. The preparation of graphite foil consisted of the synthesis of stage-1 graphite bisulfate, followed by washing with water, rapid heating of obtained expandable graphite at temperatures of 600, 800, 1000 °C with the formation of exfoliated graphite and the subsequent compression of EG into graphite foil. The structure of the materials was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and Raman spectroscopy. The correlation between EG preparation conditions, the presence of amorphous and turbostratic carbon, which influence the GF porous structure and GF gas permeance, was found. Graphite foil based on EG obtained at 600 °C had the minimal nitrogen and hydrogen permeances of 0.1110–10 and 0.4410–10 mol m-2 s-1 Pa-1, while the increase in EG preparation temperature up to 1000 °C raises GF gas permeance.
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
Handling Editor: Yaroslava Yingling.
Address correspondence to E-mail: [email protected]
https://doi.org/10.1007/s10853-020-05541-2
J Mater Sci
GRAPHICAL ABSTRACT
Introduction Exfoliated graphite (EG) is a carbon material with a crystalline structure of graphite, but which differs from it in morphology, width of graphite crystallites and the arrangement of graphite sheets in an individual particle [1, 2]. EG has been found to be a good sorbent of heavy oils [3, 4], a support for various catalysts [5] and antimicrobial agents [6], a base for electrode materials [7] and also a raw material for graphene [8]. However, one of the main industrial applications of exfoliated graphite is the production of flexible graphite foil (GF) by EG compression and manufacturing of graphite sealing materials [1, 9, 10]. The wide distribution of GF as a sealing material is due to the combination of its chemical and thermal stability, high elasticity and compressibility, and the stability at high pressure [10, 11]. The effectiveness of GF as a sealing material can be characterized by its sealability, which is the ability of the material to prevent g
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