Mechanical and thermal behaviour of cordierite–zirconia composites

Cordierite (Mg2Al4Si5O18) ceramics are susceptible of mechanical failure due to their low fracture toughness, which may hinder their application. Dispersion of ZrO2 in cordierite to improve the mechanical properties has been extensively studied. However, little is known about the effect of such additions on both the sinterability and the mechanical properties of cordierite bodies fabricated from talc, kaolin and alumina mixes with additions of monoclinic ZrO2, as most studies are concerned with additions of tetragonal ZrO2 to cordierite powders. The present paper describes the in situ fabrication, the thermal and mechanical properties of sintered cordierite-based ceramic matrix composites containing dispersed particles of ZrO2 obtained by mixing clay–talc–alumina mixtures with additions of monoclinic ZrO2 up to 40 wt.%. The results obtained clearly demonstrate that the thermal expansion coefficient (CTE), elastic moduli (E) and flexural strength (σr) were critically dependent on the mixing/milling conditions, the ZrO2 content and the retained porosity.