INTERFACIAL CHARACTERIZATION OF SILICON-CARBIDE FIBER LITHIA ALUMINA SILICA GLASS MATRIX COMPOSITES

The development of the carbon‐rich interphase in Nicalon SiC fiber/Li2O‐Al2O3–SiO2 glass matrix composites was examined as a function of processing parameters with the use of high‐resolution scanning electron microscopy and Auger electron spetroscopy. Specifically, hot‐pressing temperatures (1000°, 1100°, and 1200°C) and times (15, 30, 60, and 240 min) were systematically varied in such a manner so as to fabricate dense composites suitable for evaluation of reaction kinetics. Carbon‐rich interphase thickness, which ranged from 1400 to 5400 Å (140 to 540 nm), was observed to increase with either increasing times at constant temperature or increasing temperatures at constant time. The kinetics of formation of the carbon‐rich interphase followed a diffusion‐controlled model, with an activation energy of 25.4 kcal/mol. Copyright © 1990, Wiley Blackwell. All rights reserved