Structural ceramic nanocomposites

Structural ceramic nanocomposites are reviewed with emphasis on the Al2O3/SiC and Si3N4/SiC systems. The incorporation of a nanosized second phase, such as SiC, into a ceramic matrix can lead to an improvement in mechanical properties. It is still unclear, however, whether those improvements can directly, be related to an intrinsic 'nanocompossite effect' or to other factors. This review is divided into three parts. First, basic processing routes for nanocomposites, namely conventional powder processing, presented in detail. Second the mechanical properties of different nonocomposites are compared. Finally, models which attempt to explain the improvements in these properties are explored. It will be shown that the strength increase can best be related to a reduction in processing defect size. For applications the most interesting properties of nanocomposites are their wear, deep and high temperature performance. (C) 1997 Elsevier Science Limited.