Sol–gel synthesis of ceramic matrix composites

Sol–gel techniques have been used to produce various high temperature ceramic matrix composites including Ni/α-Al2O3, Fe/α-Al2O3, Ni/ZrO2, SiC(whisker)/α-Al2O3, and SiC(platelet)/α-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.