SOL-GEL SYNTHESIS OF CERAMIC-MATRIX COMPOSITES

Sol-gel techniques have been used to produce various high temperature ceramic matrix composites including Ni/alpha-Al2O3, Fe/alpha-Al2O3, Ni /ZrO2, SiC(whisker)/alpha-Al2O3, and SiC(platelet)/alpha-Al2O3, as wel l as chemically modified versions of some of these systems. In all cas es, the composites have displayed uniform microstructures with a high degree of dispersion between the matrix and reinforcement phases, a go al often not achieved when utilizing conventional powder mixing and pr ocessing techniques. The metal-ceramic composites investigated exhibit enhanced toughness and machinability as well as the potential for cat alytic applications due to their novel fine-scale microstructure. Like wise,, the SiC-reinforced alumina materials have been shown to be ligh ter, stiffer and tougher than pure alumina, without the use of the ext reme hot-pressing temperatures and pressures needed by conventional po wder processing approaches to produce the same results. (C) 1998 Elsev ier Science S.A. All rights reserved.