Analytical Approach for Densification of Carbon–Carbon Composites Through Isothermal and Isobaric Chemical Vapor Infiltration (ICVI) Process

Isothermal and isobaric chemical vapor infiltration (ICVI) is the classical method employed for the densification of both carbon–carbon (C–C) and ceramic matrix composites (CMC). The two governing aspects of CVI process are reaction rate and mass transport phenomenon. These dictate the process parameters required to enhance the densification rate and minimize density gradients. However, there is an intrinsic conflict between favorable conditions required for deposition reactions and mass transport of reactant species. ICVI relies on diffusion for species transport as the rate-determining step. So, the process results in only outer surfaces being densified and blocking the transport further. Thus, inner surfaces are densified partially causing density variations within the component. Alternatively, to achieve minimal density gradients, the process duration becomes uneconomically high. Also, ICVI requires intermittent machining of component for further densification. These process challenges can be surpassed by optimal selection of process parameters. The optimization of process parameters to favorably density a preform has been studied by various researchers. However, for component manufacturing, the process parameters need to be evolved considering various factors. In the present study, these parameters are evolved through simulations using Ansys Fluent. Various configurations were investigated to simulate the conditions to achieve the desired flow patterns. A single pore model is adopted to examine the densification characteristics. The study further highlights different aspects of process methodologies to be adopted to achieve the desired and consistent performance of the material synthesized through ICVI.