Microwave-enhanced chemical vapor infiltration: a sharp interface model

A simple one-dimensional model for describing CVI into a fibrous preform is presented and analyzed. The derivation requires that the thermal and elect rical properties of the preform and substrate are disparate. Mathematically the model takes the form of a moving-boundary problem., where the boundary is the interface between the preform and the substrate. Effects of heat lo ss and radiation at the boundaries and the nonlinear dependence of dielectr ic parameters on temperature are all taken into account, in addition to the spatial dependence on gas concentration. Processing times for different po wer levels and inlet concentrations for different initial substrate thickne sses are obtained, and the implications to processing strategies are discus sed.