A two-process model for study of the effect of fiber preform structure on isothermal chemical vapor infiltration of silicon carbide matrix composites

A two-process model was developed according to the infiltration-induced structural evolvement in the porous fiber preforms and the physicochemical phenomena involved in the Isothermal Chemical Vapor Infiltration (ICVI) process. The structural evolvement was modeled by representing the void space by a small pore among filaments and a large pore among bundles. The mathematical model was implemented by finite-element method to investigate the effect of the preform structure on the deposition uniformity, processing time and final average density. Calculation results imply that the fiber preform structure plays a dramatic role in determining the deposition uniformity, processing time and final average density. The fiber preforms consisted of filaments and bundles of moderate diameters are preferable by combined consideration of the highest final average density, the relatively low density gradient and the relatively short infiltration time.