Physicochemical Foundations of Compactification of the Porous Structure of Pyrocarbon from the Gas Phase
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PHYSICOCHEMICAL FOUNDATIONS OF COMPACTIFICATION OF THE POROUS STRUCTURE OF PYROCARBON FROM THE GAS PHASE V. А. Skachkov1, 2 and О. R. Berezhnaya1
UDC 661.666:541.124:539.26
We propose a model of low-temperature compactification of the porous structure of carbonized coal plastic in a flow slab reactor and develop a procedure for the determination of the distribution of pyrocarbon over the thickness of the wall of the compactified coal plastic. Keywords: flow reactor, porous structure, carbonized coal plastics, X-ray diffraction parameters.
The field of application of carbon composite materials (CCM) depends on the decrease in their cost determined by the power consumption. Decreasing the temperature of compactification of the porous structures of carbonized composite materials down to 600–700°С with the help of liquefied gases, one can find an approach to the problem of energy saving. The improvement of the structure and properties of carbonized coal plastics based on phenol-formaldehyde matrices is based on the procedure of filling of porous structures with pyrolytic carbon (PC) from the gas phase [1–3]. The processes of its getting are described for methane in [4, 5], for acetylene in [6], and for propane in [7, 8]. The problems of compactification of the porous structure of CCM are considered in [1–3]. However, the actual structure of their pores is not studied and its influence on the process of compactification was not analyzed. This is why the experimental determination of the distribution of PC over the thickness of compactified carbonized carbon composites is of significant interest. In what follows, we develop a model of low-temperature deposition of PC from propane in the porous structure of carbonized coal plastic, and propose new methods of the numerical-experimental determination of the distribution of PC across the thickness of the wall of pyrolytically compactified coal plastic and across the thickness of specimens in different modes of pyrolytic compactification. Evaluation of the Content of Pyrocarbon To determine the content of PC, we use a procedure based on the evaluation of the influence of PC content on the intensity of scattering of electrons from the basal plane of PC in the composition of the main components of carbonized coal plastics, namely, carbon fibers, pyrocarbon, and the carbonized matrix. The intensity of scattering of electrons at the angle 2θ to their primary beam can be determined as follows [9, 10]:
I (hkl ) = A(θ, µ)h 2 λ 3 L(θ)P(θ)F 2 (hkl) exp(−2M )p ,
(1)
where A(θ, µ) is the absorption factor depending on the scattering angle θ and the linear attenuation coeffi1 2
Zaporizhzhya State Engineering Academy, Zaporizhzhya, Ukraine. Corresponding author; e-mail: [email protected].
Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 50, No. 4, pp. 94–99, July–August, 2014. Original article submitted November 4, 2013. 1068-820X/15/5004–0585
© 2015
Springer Science+Business Media New York
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cient µ , n is the number o
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