Analysis of reactive melt infiltration in the processing of ceramics and ceramic composites

A model describing the reactive melt infiltration (RMI) of liquid silicon into a carbonaceous preform is solved and the simulation is compared with experimental results. The finite-element method is used to solve the equations in arbitrary geometries. The model is consistent with experimental results in that it predicts the infiltration rate in a reacting and nonreacting system and the magnitude and functional form of the temperature rise in the sample caused by the exothermic reaction of silicon with carbon to form silicon carbide. The model is particularly sensitive to two parameters, the pore neck diameter (d(1)) as defined by an ideal repeating pore unit, and the SiC reaction barrier thickness (delta(0)) which forms when silicon reacts with carbon to form a SiC skin around the particles. The sensitivity of the solution to these two parameters is demonstrated. It is suggested that d(1) and delta(0) be chosen based on experimental measurements of infiltration rate and temperature excursion during silicon infiltration. (C) 1998 Elsevier Science Ltd. All rights reserved.