A 2-DIMENSIONAL MODEL OF CHEMICAL-VAPOR INFILTRATION WITH RADIO-FREQUENCY HEATING

A comprehensive, two-dimensional, self-consistent model was developed and used to simulate chemical vapor infiltration of fiber-reinforced c omposite materials with radio frequency heating. The model included eq uations for energy transport, multicomponent mass transport, and pore structure evolution, coupled to Maxwell's equations to determine self- consistently the power absorbed by the preform from a radio frequency induction coil. The model equations were solved by a finite element me thod to study carbon chemical vapor infiltration in a cylindrical carb on preform. Simulations for a constant absorbed power showed that dens ification of the preform proceeds in an ''inside out'' manner, first i n the radial direction and subsequently in the axial direction, for th e aspect ratio studied. The power density distribution in the preform evolves in a complex manner as densified regions absorb more energy wi th increased densification. This may result in thermal runaway during the infiltration process and entrapment of porosity in the interior of the preform. Comparison of simulated results with reported experiment al data showed semiquantitative agreement of important trends. A more accurate description of material properties is required for a quantita tive match with the data.