Effect of preparation conditions on gas permeability and sealing efficiency of graphite foilстатьяИсследовательская статья
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Аннотация:Nitrogen permeability of graphite foil (GF) based on expandable graphite with
different oxidation degrees was measured. Expandable graphite was obtained
by the chemical interaction of graphite and nitric acid with the formation of
graphite nitrate of II, III, IV stages and by the electrochemical oxidation of
graphite in HNO3 solution followed by water washing. The expandable graphite
samples were heat-treated at 800 deg.C with the formation of exfoliated graphite
followed by pressing the exfoliated graphite into GF. The samples of exfoliated
graphite and graphite foil were investigated by XRD, SEM, Raman spectroscopy
and mercury porosimetry methods. GF nitrogen permeance decreases from
19.7x10^-10 to 6.7x10^-10 mol*m^-2*s^-1*Pa^-1 with decreasing a stage number
of graphite nitrate from IV to II. Gas permeance of GF based on electrochemical
expandable graphite decreases by an order of magnitude up to 0.2x10^-10
mol*m^-2*s^-1*Pa^-1 in comparison with GF based on graphite nitrate of II stage.
Thus, it is possible to produce the graphite foil material with a wide range of
permeability and, respectively, the different sealing efficiency by varying the
oxidation degree of the initial graphite matrix in the step of obtaining graphite
intercalation compounds and expandable graphite.