Mechanical and thermal shock properties of duplex-ceramics - a review

The microstructural design concept of duplex-ceramics is based on relatively large (10-100 μm diameter) spherical pressure zones dispersed in a ceramic matrix. This paper gives an overview of the mechanical and thermal shock properties of duplex-ceramics. The incorporation of pressure zones into a brittle ceramic matrix, in genernal, reduces its strength, but results in increased quasi-ductility, pronounced toughness behaviour (R-curve behaviour), and increased flaw and thermal shock resistance. Many different visible effects have been observed in duplex-ceramics. Attempts have been made to study their contribution to the R-curve. Also reported is an attempt to relate, and furthermore predict, the observed change in mechanical and thermal shock properties by an empirically derived measure, the internal stress-intensity factor, Ki, associated with such zones. 48 refs., 21 figs