An Effective Medium Approach for Modeling Chemical Vapor Infiltration of Porous Ceramic Materials


Gupte S.M., Tsamopoulos J.A.


The process of chemical vapor infiltration for densification of porous ceramic preforms consists of reactant diffusion and decomposition followed by solid product deposition in the porous body. A mathematical model for isothermal and nonisothermal CVI is presented where the transient porous structure is approximated by a Bethe lattice. Concepts of percolation theory are used to account for utilized, unutilized, and filled pore space. Diffusion coefficients are evaluated using the effective medium theory. The effect of pore connectivity, porosity distribution, operating pressure, inlet temperature, hot-face temperature, and length of the preform on densification is studied. Optimum conditions for low residual porosities and uniform densification are suggested. © 1990, The Electrochemical Society, Inc. All rights reserved.


DOI: 10.1149/1.2086741