ANALYSIS OF REACTIVE MELT INFILTRATION IN THE PROCESSING OF CERAMICS AND CERAMIC COMPOSITES

A model describing the reactive melt infiltration (RMI) of liquid sili con into a carbonaceous preform is solved and the simulation is compar ed with experimental results. The finite-element method is used to sol ve the equations in arbitrary geometries. The model is consistent with experimental results in that it predicts the infiltration rate in a r eacting and nonreacting system and the magnitude and functional form o f the temperature rise in the sample caused by the exothermic reaction of silicon with carbon to form silicon carbide. The model is particul arly sensitive to two parameters, the pore neck diameter (d(1)) as def ined by an ideal repeating pore unit, and the SiC reaction barrier thi ckness (delta(0)) which forms when silicon reacts with carbon to form a SiC skin around the particles. The sensitivity of the solution to th ese two parameters is demonstrated. It is suggested that d(1) and delt a(0) be chosen based on experimental measurements of infiltration rate and temperature excursion during silicon infiltration. (C) 1998 Elsev ier Science Ltd. All rights reserved.