Kinetic analysis of the chemical vapor deposition of si from SiCl <inf>4</inf> - H<inf>2</inf> for the production of biomorphic Si <inf>3</inf>N<inf>4</inf> ceramics

Abstract:

Biomorphic porous Si3N4 ceramics derived from paper were produced in a three step process consisting of carbonization of the paper preforms to carbon bio-templates, Cb, (1), chemical vapour infiltration (CVI) of Cb with Si from SiCl4/H2 (2) and finally high temperature reaction of the deposited Si with a N 2/H2 mixture to Si3N4 (3). In the present work the CVI step is analyzed with respect to the kinetics of the deposition reaction. For that a series of experiments have been performed on non-porous substrates in order to define regions of parameters, where the overall process is limited by the surface reaction kinetics, which is a precondition for a homogeneous infiltration of the porous Cb template. Furthermore, the deposition rate of Si from SiCl4/H 2 was modelled by CHEMKIN software using a simple power law expression without and with an inhibition term. The results of the simulation of the deposition process with the model, concerning the inhibiting effect of the by-product HCl show good agreement with the experimental data in a wide region of deposition conditions.

Año de publicación:

2005

Keywords:

Fuente:

scopus