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Chemistry and Kinetics of Heterogeneous Reaction Mechanism for Chemical Vapor Infiltration of Pyrolytic Carbon from Propane
journal contribution
posted on 2014-11-12, 00:00 authored by Z. P. Tang, A. J. Li, Z. W. Zhang, X. Ma, W. Wang, J. M. Fang, R. C. BaiA heterogeneous reaction mechanism
based on elementary reaction
steps is proposed for the prediction of pyrolytic carbon deposition
in chemical vapor infiltration, involving 72 surface species and 277
surface elementary reactions. A “prototype” gas-phase
reaction is chosen to match with the corresponding surface reaction,
and correction methods for kinetic data are also proposed for three
kinds of surface reactions (i.e., surface/gas reactions, unimolecular
surface reactions, surface/surface reactions) in the present work.
Simulation results of deposition kinetics and gas-phase compositions
of propane pyrolysis are validated by previously published experimental
results of Marquaire’s group, with a surface to volume ratio
from 5 to 175 cm–1 and temperature from 1173 to
1323 K. The reaction pathways of the heterogeneous surface reactions
and homogeneous gas-phase reactions are studied on the basis of the
reaction flow rate analysis. An acceptable agreement indicates that
the present heterogeneous reaction mechanism is reasonable, and acetylene,
ethylene, and benzene are recognized as the main precursors of the
pyrolytic carbon deposition at the present processing conditions.