THE COATING OF CONTINUOUS CARBON-FIBER BUNDLES WITH SIC BY CHEMICAL-VAPOR-DEPOSITION - A MATHEMATICAL-MODEL FOR THE CVD-PROCESS

A mathematical model is presented for the description of the chemical vapor deposition of SIC on continuous fibers bundles consisting of sev eral hundreds or even several thousands of individual filaments. Based on chemical engineering kinetics, the model predicts the mean layer t hickness and the layer thickness distribution on the monofilaments of the bundle. The model presupposes that the kinetics of the deposition on the outer surface, the effective diffusion coefficient and the geom etry of the fiber bundle are known. The results of the calculations ar e presented in terms of the change of the diameter of the fibers as a function of the distance from the axis of the bundle for different pos itions in the reactor and as the relative concentration of the precurs or as a function of the distance from the axis of the bundle for diffe rent positions in the reactor and for different deposition conditions. Using the model presented the mean layer thickness was calculated for different reaction conditions and a comparison between calculated and measured values is given. (C) 1998 Elsevier Science Ltd. All rights r eserved.