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 well as chemically modified versions of some of these systems. In all cases, the composites have displayed uniform microstructures with a high degree of dispersion between the matrix and reinforcement phases, a goal often not achieved when utilizing conventional powder mixing and processing techniques. The metal-ceramic composites investigated exhibit enhanced toughness and machinability as well as the potential for catalytic applications due to their novel fine-scale microstructure. Likewise,, the SiC-reinforced alumina materials have been shown to be lighter, stiffer and tougher than pure alumina, without the use of the extreme hot-pressing temperatures and pressures needed by conventional powder processing approaches to produce the same results. (C) 1998 Elsevier Science S.A. All rights reserved.