Modeling of chemical vapor infiltration process for fabrication of carbon-carbon composites by finite difference methods

A finite difference (FD)-based method is proposed to describe the chemical vapor infiltration (CVI) processes for fabrication of carbon-carbon composites. The continuous, unsteady-state CVI processing can be divided into many discrete steady-state depositions by this model. Long cylindroid unidirectional carbon-carbon composites are prepared using the isothermal CVI technique to verify the accuracy of the FD methods. Experimental research shows that the modeling values are in good agreement with experimental data. The deviation of infiltration threshold and final bulk density are both minor with error less than 10%. Moreover, computational porosity at different cross-sections of preforms is also consistent with experimental values. The effect of deposition temperature, fiber volume fraction, and size of composites, on densification is analyzed using the FD model, which results in some useful information. Bulk density, infiltration threshold, uniformity, are described quantitatively by regression equations. (C) 1999 Elsevier Science Ltd. All rights reserved.